DataFrame#
Most DataFrame methods are lazy, meaning that they do not execute computation immediately when invoked. Instead, these operations are enqueued in the DataFrame's internal query plan, and are only executed when Execution DataFrame methods are called.
DataFrame #
DataFrame(builder: LogicalPlanBuilder)
A Daft DataFrame is a table of data.
It has columns, where each column has a type and the same number of items (rows) as all other columns.
Constructs a DataFrame according to a given LogicalPlan.
Users are expected instead to call the classmethods on DataFrame to create a DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
builder | LogicalPlanBuilder | LogicalPlan describing the steps required to arrive at this DataFrame | required |
Methods:
| Name | Description |
|---|---|
__arrow_c_schema__ | |
__arrow_c_stream__ | Export as an Arrow C stream (PyCapsule). |
__contains__ | Returns whether the column exists in the dataframe. |
__getitem__ | Gets a column from the DataFrame as an Expression ( |
__iter__ | Alias of |
__len__ | Returns the count of rows when dataframe is materialized. |
agg | Perform aggregations on this DataFrame. |
agg_concat | Performs a global concatenation agg on the DataFrame. |
agg_list | Performs a global list agg on the DataFrame. |
agg_set | Performs a global set agg on the DataFrame (ignoring nulls). |
any_value | Returns an arbitrary value on this DataFrame. |
collect | Executes the entire DataFrame and materializes the results. |
concat | Concatenates two DataFrames together in a "vertical" concatenation. |
count | Performs a global count on the DataFrame. |
count_distinct | Performs a global count of distinct values on the DataFrame. |
count_rows | Executes the Dataframe to count the number of rows. |
describe | Returns the Schema of the DataFrame, which provides information about each column, as a new DataFrame. |
distinct | Computes distinct rows, dropping duplicates. |
drop_duplicates | Computes distinct rows, dropping duplicates. |
drop_nan | Drops rows that contains NaNs. If cols is None it will drop rows with any NaN value. |
drop_null | Drops rows that contains NaNs or NULLs. If cols is None it will drop rows with any NULL value. |
except_all | Returns the set difference of two DataFrames, considering duplicates. |
except_distinct | Returns the set difference of two DataFrames. |
exclude | Drops columns from the current DataFrame by name. |
explain | Prints the (logical and physical) plans that will be executed to produce this DataFrame. |
explode | Explodes a List column, where every element in each row's List becomes its own row, and all other columns in the DataFrame are duplicated across rows. |
filter | Filters rows via a predicate expression, similar to SQL |
groupby | Performs a GroupBy on the DataFrame for aggregation. |
intersect | Returns the intersection of two DataFrames. |
intersect_all | Returns the intersection of two DataFrames, including duplicates. |
into_batches | Splits or coalesces DataFrame to partitions of size |
into_partitions | Splits or coalesces DataFrame to |
iter_partitions | Begin executing this dataframe and return an iterator over the partitions. |
iter_rows | Return an iterator of rows for this dataframe. |
join | Column-wise join of the current DataFrame with an |
join_asof | Point-in-time (asof) join: each left row matches the nearest right row according to the chosen strategy. |
limit | Limits the rows in the DataFrame to the first |
max | Performs a global max on the DataFrame. |
mean | Performs a global mean on the DataFrame. |
melt | Alias for unpivot. |
min | Performs a global min on the DataFrame. |
num_partitions | Returns the number of partitions that will be used to execute this DataFrame. |
offset | Returns a new DataFrame by skipping the first |
pipe | Apply the function to this DataFrame. |
pivot | Pivots a column of the DataFrame and performs an aggregation on the values. |
product | Performs a global product on the DataFrame. |
repartition | Repartitions DataFrame to |
sample | Samples rows from the DataFrame. |
schema | Returns the Schema of the DataFrame, which provides information about each column, as a Python object. |
select | Creates a new DataFrame from the provided expressions, similar to a SQL |
show | Executes enough of the DataFrame in order to display the first |
shuffle | Randomly reorders rows of the DataFrame. |
skew | Performs a global skew on the DataFrame. |
skip_existing | Filter out rows whose key(s) already exist in existing data (i.e., already processed rows). |
sort | Sorts DataFrame globally. |
stddev | Performs a global standard deviation on the DataFrame. |
sum | Performs a global sum on the DataFrame. |
summarize | Returns column statistics for the DataFrame. |
to_arrow | Converts the current DataFrame to a pyarrow Table. |
to_arrow_iter | Return an iterator of pyarrow recordbatches for this dataframe. |
to_dask_dataframe | Converts the current Daft DataFrame to a Dask DataFrame. |
to_pandas | Converts the current DataFrame to a pandas DataFrame. |
to_pydict | Converts the current DataFrame to a python dictionary. The dictionary contains Python lists of Python objects for each column. |
to_pylist | Converts the current Dataframe into a python list. |
to_ray_dataset | Converts the current DataFrame to a Ray Dataset which is useful for running distributed ML model training in Ray. |
to_torch_iter_dataset | Convert the current DataFrame into a |
to_torch_map_dataset | Convert the current DataFrame into a map-style Torch Dataset for use with PyTorch. |
transform | Apply a function that takes and returns a DataFrame. |
union | Returns the distinct union of two DataFrames. |
union_all | Returns the union of two DataFrames, including duplicates. |
union_all_by_name | Returns the union of two DataFrames, including duplicates, with columns matched by name. |
union_by_name | Returns the distinct union by name. |
unique | Computes distinct rows, dropping duplicates. |
unpivot | Unpivots a DataFrame from wide to long format. |
var | Performs a global variance on the DataFrame. |
where | Filters rows via a predicate expression, similar to SQL |
with_column | Adds a column to the current DataFrame with an Expression, equivalent to a |
with_column_renamed | Renames a column in the current DataFrame. |
with_columns | Adds columns to the current DataFrame with Expressions, equivalent to a |
with_columns_renamed | Renames multiple columns in the current DataFrame. |
write_bigtable | Write a DataFrame into a Google Cloud Bigtable table. |
write_clickhouse | Writes the DataFrame to a ClickHouse table. |
write_csv | Writes the DataFrame as CSV files, returning a new DataFrame with paths to the files that were written. |
write_deltalake | Writes the DataFrame to a Delta Lake table, returning a new DataFrame with the operations that occurred. |
write_huggingface | Write a DataFrame into a Hugging Face dataset. |
write_iceberg | Writes the DataFrame to an Iceberg table, returning a new DataFrame with the operations that occurred. |
write_json | Writes the DataFrame as JSON files, returning a new DataFrame with paths to the files that were written. |
write_lance | Writes the DataFrame to a Lance table. |
write_paimon | Writes the DataFrame to an Apache Paimon table, returning a summary DataFrame. |
write_parquet | Writes the DataFrame as parquet files, returning a new DataFrame with paths to the files that were written. |
write_sink | Writes the DataFrame to the given DataSink. |
write_sql | Write the DataFrame to a SQL database and return write metrics. |
write_turbopuffer | Writes the DataFrame to a Turbopuffer namespace. |
Attributes:
| Name | Type | Description |
|---|---|---|
column_names | list[str] | Returns column names of DataFrame as a list of strings. |
columns | list[Expression] | Returns column of DataFrame as a list of Expressions. |
metrics | RecordBatch | None | |
Source code in daft/dataframe/dataframe.py
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column_names #
column_names: list[str]
Returns column names of DataFrame as a list of strings.
Returns:
| Type | Description |
|---|---|
list[str] | List[str]: Column names of this DataFrame. |
columns #
columns: list[Expression]
Returns column of DataFrame as a list of Expressions.
Returns:
| Type | Description |
|---|---|
list[Expression] | List[Expression]: Columns of this DataFrame. |
__arrow_c_schema__ #
__arrow_c_schema__() -> Any
Source code in daft/dataframe/dataframe.py
5654 5655 | |
__arrow_c_stream__ #
__arrow_c_stream__(requested_schema: Any = None) -> Any
Export as an Arrow C stream (PyCapsule).
This triggers materialization of the DataFrame. Enables pa.table(daft_df) and other Arrow PyCapsule consumers.
Source code in daft/dataframe/dataframe.py
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__contains__ #
__contains__(col_name: str) -> bool
Returns whether the column exists in the dataframe.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
col_name | str | column name | required |
Returns:
| Name | Type | Description |
|---|---|---|
bool | bool | whether the column exists in the dataframe. |
Examples:
1 2 3 | |
True Source code in daft/dataframe/dataframe.py
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__getitem__ #
__getitem__(item: int) -> Expression
__getitem__(item: str) -> Expression
__getitem__(item: slice) -> DataFrame
__getitem__(item: Iterable) -> DataFrame
__getitem__(item: int | str | slice | Iterable[str | int]) -> Union[Expression, DataFrame]
Gets a column from the DataFrame as an Expression (df["mycol"]).
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
item | Union[int, str, slice, Iterable[Union[str, int]]] | The column to get. Can be an integer index, a string column name, a slice for multiple columns, or an iterable of column names or indices. | required |
Returns:
| Type | Description |
|---|---|
Union[Expression, DataFrame] | Union[Expression, DataFrame]: If a single column is requested, returns an Expression representing that column. |
Union[Expression, DataFrame] | If multiple columns are requested (via a slice or iterable), returns a new DataFrame containing those columns. |
Examples:
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col(a)
col(b)
col(a)
╭───────┬───────╮
│ b ┆ c │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╰───────┴───────╯
(No data to display: Dataframe not materialized, use .collect() to materialize)
╭───────┬───────╮
│ a ┆ c │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╰───────┴───────╯
(No data to display: Dataframe not materialized, use .collect() to materialize)
╭───────┬───────╮
│ a ┆ b │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╰───────┴───────╯
(No data to display: Dataframe not materialized, use .collect() to materialize)
╭───────┬───────╮
│ a ┆ b │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╰───────┴───────╯
(No data to display: Dataframe not materialized, use .collect() to materialize)
╭───────┬───────┬───────╮
│ a ┆ b ┆ c │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╰───────┴───────┴───────╯
(No data to display: Dataframe not materialized, use .collect() to materialize) Source code in daft/dataframe/dataframe.py
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__iter__ #
__iter__() -> Iterator[dict[str, Any]]
Alias of self.iter_rows() with default arguments for convenient access of data.
Returns:
| Type | Description |
|---|---|
Iterator[dict[str, Any]] | Iterator[dict[str, Any]]: An iterator over the rows of the DataFrame, where each row is a dictionary |
Iterator[dict[str, Any]] | mapping column names to values. |
Examples:
1 2 3 4 | |
{'foo': 1, 'bar': 'a'}
{'foo': 2, 'bar': 'b'}
{'foo': 3, 'bar': 'c'} Tip
See also df.iter_rows(): iterator over rows with more options
Source code in daft/dataframe/dataframe.py
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__len__ #
__len__() -> int
Returns the count of rows when dataframe is materialized.
If dataframe is not materialized yet, raises a runtime error.
Returns:
| Name | Type | Description |
|---|---|---|
int | int | count of rows. |
Examples:
1 2 3 4 | |
3 Source code in daft/dataframe/dataframe.py
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agg #
agg(*to_agg: Expression | Iterable[Expression]) -> DataFrame
Perform aggregations on this DataFrame.
Allows for mixed aggregations for multiple columns and will return a single row that aggregated the entire DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*to_agg | Expression | aggregation expressions | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with aggregated results |
Examples:
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╭─────────┬────────────────────┬────────────────────┬───────────╮
│ test1 ┆ test2 ┆ total_min ┆ total_max │
│ --- ┆ --- ┆ --- ┆ --- │
│ Float64 ┆ Float64 ┆ Float64 ┆ Float64 │
╞═════════╪════════════════════╪════════════════════╪═══════════╡
│ 0.55 ┆ 0.8500000000000001 ┆ 0.6000000000000001 ┆ 0.85 │
╰─────────┴────────────────────┴────────────────────┴───────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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agg_concat #
agg_concat(*cols: ColumnInputType, delimiter: str | None = None) -> DataFrame
Performs a global concatenation agg on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns that are lists or strings to concatenate | () |
delimiter | str | None | Optional delimiter to insert between concatenated string values. Only supported for string columns. | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Globally aggregated list or string. Should be a single row. |
Examples:
1 2 3 4 5 | |
╭──────────────╮
│ col_a │
│ --- │
│ List[Int64] │
╞══════════════╡
│ [1, 2, 3, 4] │
╰──────────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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agg_list #
agg_list(*cols: ColumnInputType) -> DataFrame
Performs a global list agg on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to form into a list | () |
Returns: DataFrame: Globally aggregated list. Should be a single row.
Examples:
1 2 3 4 5 | |
╭─────────────╮
│ col_a │
│ --- │
│ List[Int64] │
╞═════════════╡
│ [1, 2, 3] │
╰─────────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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agg_set #
agg_set(*cols: ColumnInputType) -> DataFrame
Performs a global set agg on the DataFrame (ignoring nulls).
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to form into a set | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Globally aggregated set. Should be a single row. |
Examples:
1 2 3 4 5 | |
╭─────────────╮
│ col_a │
│ --- │
│ List[Int64] │
╞═════════════╡
│ [1, 2, 3] │
╰─────────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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any_value #
any_value(*cols: ColumnInputType) -> DataFrame
Returns an arbitrary value on this DataFrame.
Values for each column are not guaranteed to be from the same row.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to get an arbitrary value from | () |
Returns: DataFrame: DataFrame with any values.
Examples:
1 2 3 4 | |
╭───────╮
│ col_a │
│ --- │
│ Int64 │
╞═══════╡
│ 1 │
╰───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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collect #
collect(num_preview_rows: int | None = 8) -> DataFrame
Executes the entire DataFrame and materializes the results.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
num_preview_rows | int | None | Number of rows to preview. Defaults to 8. | 8 |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with materialized results. |
Note
This call is blocking and will execute the DataFrame when called
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ x ┆ y │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
╰───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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concat #
Concatenates two DataFrames together in a "vertical" concatenation.
The resulting DataFrame has number of rows equal to the sum of the number of rows of the input DataFrames.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | other DataFrame to concatenate | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with rows from |
Note
DataFrames being concatenated must have exactly the same schema. You may wish to use the df.select() and expr.cast() methods to ensure schema compatibility before concatenation.
Examples:
1 2 3 4 5 | |
╭───────┬───────╮
│ a ┆ b │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 3 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 5 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 6 ┆ 8 │
╰───────┴───────╯
(Showing first 4 of 4 rows) Source code in daft/dataframe/dataframe.py
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count #
count(*cols: ColumnInputType | int) -> DataFrame
Performs a global count on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression, int] | columns to count | () |
Returns: DataFrame: Globally aggregated count. Should be a single row.
Examples:
If no columns are specified (i.e. in the case you call df.count()), or only the literal string "", this functions very similarly to a COUNT() operation in SQL and will return a new dataframe with a single column with the name "count".
1 2 3 4 | |
╭────────╮
│ count │
│ --- │
│ UInt64 │
╞════════╡
│ 3 │
╰────────╯
(Showing first 1 of 1 rows) However, specifying some column names would instead change the behavior to count all non-null values, similar to a SQL command for SELECT COUNT(foo), COUNT(bar) FROM df. Also, using df.count(col("*")) will expand out into count() for each column.
1 | |
╭────────┬────────╮
│ foo ┆ bar │
│ --- ┆ --- │
│ UInt64 ┆ UInt64 │
╞════════╪════════╡
│ 1 ┆ 2 │
╰────────┴────────╯
(Showing first 1 of 1 rows) 1 | |
╭────────┬────────┬────────╮
│ foo ┆ bar ┆ baz │
│ --- ┆ --- ┆ --- │
│ UInt64 ┆ UInt64 ┆ UInt64 │
╞════════╪════════╪════════╡
│ 1 ┆ 2 ┆ 3 │
╰────────┴────────┴────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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count_distinct #
count_distinct(*cols: ColumnInputType) -> DataFrame
Performs a global count of distinct values on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to count distinct values | () |
Returns: DataFrame: Globally aggregated count of distinct values. Should be a single row.
Examples:
1 2 3 4 | |
╭────────╮
│ col_a │
│ --- │
│ UInt64 │
╞════════╡
│ 3 │
╰────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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count_rows #
count_rows() -> int
Executes the Dataframe to count the number of rows.
Returns:
| Name | Type | Description |
|---|---|---|
int | int | count of the number of rows in this DataFrame. |
Examples:
1 2 3 | |
3 Note
This will execute the DataFrame and return the number of rows in it.
Source code in daft/dataframe/dataframe.py
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describe #
describe() -> DataFrame
Returns the Schema of the DataFrame, which provides information about each column, as a new DataFrame.
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A dataframe where each row is a column name and its corresponding type. |
Examples:
1 2 3 | |
╭─────────────┬────────╮
│ column_name ┆ type │
│ --- ┆ --- │
│ String ┆ String │
╞═════════════╪════════╡
│ a ┆ Int64 │
├╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ b ┆ String │
╰─────────────┴────────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
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distinct #
distinct(*on: ColumnInputType) -> DataFrame
Computes distinct rows, dropping duplicates.
Optionally, specify a subset of columns to perform distinct on.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*on | Union[str, Expression] | columns to perform distinct on. Defaults to all columns. | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame that has only distinct rows. |
Examples:
1 2 3 4 5 6 7 8 9 | |
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1 ┆ 4 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 8 │
╰───────┴───────┴───────╯
(Showing first 2 of 2 rows)
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1 ┆ 4 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 8 │
╰───────┴───────┴───────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
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drop_duplicates #
drop_duplicates(*subset: ColumnInputType) -> DataFrame
Computes distinct rows, dropping duplicates.
Alias for DataFrame.distinct.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*subset | Union[str, Expression] | columns to perform distinct on. Defaults to all columns. | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame that has only distinct rows. |
Examples:
1 2 3 4 5 | |
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1 ┆ 4 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 8 │
╰───────┴───────┴───────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
2887 2888 2889 2890 2891 2892 2893 2894 2895 2896 2897 2898 2899 2900 2901 2902 2903 2904 2905 2906 2907 2908 2909 2910 2911 2912 2913 2914 2915 2916 2917 | |
drop_nan #
drop_nan(*cols: ColumnInputType) -> DataFrame
Drops rows that contains NaNs. If cols is None it will drop rows with any NaN value.
If column names are supplied, it will drop only those rows that contains NaNs in one of these columns.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | str | column names by which rows containing nans/NULLs should be filtered | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame without NaNs in specified/all columns |
Examples:
1 2 3 | |
╭─────────╮
│ a │
│ --- │
│ Float64 │
╞═════════╡
│ 1 │
├╌╌╌╌╌╌╌╌╌┤
│ 2.2 │
├╌╌╌╌╌╌╌╌╌┤
│ 3.5 │
╰─────────╯
(Showing first 3 of 3 rows) 1 2 3 | |
╭─────────╮
│ a │
│ --- │
│ Float64 │
╞═════════╡
│ 1.6 │
├╌╌╌╌╌╌╌╌╌┤
│ 2.5 │
├╌╌╌╌╌╌╌╌╌┤
│ 3.3 │
╰─────────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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drop_null #
drop_null(*cols: ColumnInputType) -> DataFrame
Drops rows that contains NaNs or NULLs. If cols is None it will drop rows with any NULL value.
If column names are supplied, it will drop only those rows that contains NULLs in one of these columns.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | str | column names by which rows containing nans should be filtered | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame without missing values in specified/all columns |
Examples:
1 2 3 | |
╭─────────╮
│ a │
│ --- │
│ Float64 │
╞═════════╡
│ 1.6 │
├╌╌╌╌╌╌╌╌╌┤
│ 2.5 │
├╌╌╌╌╌╌╌╌╌┤
│ NaN │
╰─────────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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except_all #
Returns the set difference of two DataFrames, considering duplicates.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | DataFrame to except with | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with the set difference of the two DataFrames, considering duplicates |
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ a ┆ b │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
╰───────┴───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
5325 5326 5327 5328 5329 5330 5331 5332 5333 5334 5335 5336 5337 5338 5339 5340 5341 5342 5343 5344 5345 5346 5347 5348 5349 5350 5351 5352 | |
except_distinct #
Returns the set difference of two DataFrames.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | DataFrame to except with | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with the set difference of the two DataFrames |
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ a ┆ b │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 2 ┆ 5 │
╰───────┴───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
5296 5297 5298 5299 5300 5301 5302 5303 5304 5305 5306 5307 5308 5309 5310 5311 5312 5313 5314 5315 5316 5317 5318 5319 5320 5321 5322 5323 | |
exclude #
exclude(*names: str) -> DataFrame
Drops columns from the current DataFrame by name.
This is equivalent of performing a select with all the columns but the ones excluded.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*names | str | names to exclude | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with some columns excluded. |
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ y ┆ z │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 4 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 5 ┆ 8 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 6 ┆ 9 │
╰───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
2997 2998 2999 3000 3001 3002 3003 3004 3005 3006 3007 3008 3009 3010 3011 3012 3013 3014 3015 3016 3017 3018 3019 3020 3021 3022 3023 3024 3025 3026 3027 3028 3029 | |
explain #
explain(show_all: bool = False, format: str = 'ascii', simple: bool = False, file: IOBase | None = None) -> Any
Prints the (logical and physical) plans that will be executed to produce this DataFrame.
Defaults to showing the unoptimized logical plan. Use show_all=True to show the unoptimized logical plan, the optimized logical plan, and the physical plan.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
show_all | bool | Whether to show the optimized logical plan and the physical plan in addition to the unoptimized logical plan. | False |
format | str | The format to print the plan in. one of 'ascii' or 'mermaid' | 'ascii' |
simple | bool | Whether to only show the type of op for each node in the plan, rather than showing details of how each op is configured. | False |
file | Optional[IOBase] | Location to print the output to, or defaults to None which defaults to the default location for print (in Python, that should be sys.stdout) | None |
Returns:
| Type | Description |
|---|---|
Any | Union[None, str, MermaidFormatter]: - If |
Examples:
1 2 3 4 5 6 7 8 9 10 | |
== Unoptimized Logical Plan ==
* Project: col(x) * col(x) as x
|
* Source:
| Number of partitions = 1
| Output schema = x#Int64
Set `show_all=True` to also see the Optimized and Physical plans. This will run the query optimizer. Source code in daft/dataframe/dataframe.py
248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 291 292 293 294 295 296 297 298 299 300 301 302 303 304 305 306 307 308 309 310 311 312 313 314 315 316 317 318 319 320 321 322 323 324 325 326 327 328 329 330 331 332 333 334 335 336 337 338 339 340 341 342 343 344 345 346 347 348 349 350 | |
explode #
explode(*columns: ColumnInputType, index_column: ColumnInputType | None = None, ignore_empty_and_null: bool = False) -> DataFrame
Explodes a List column, where every element in each row's List becomes its own row, and all other columns in the DataFrame are duplicated across rows.
If multiple columns are specified, each row must contain the same number of items in each specified column.
By default, exploding Null values or empty lists will create a single Null entry (see example below). Set ignore_empty_and_null=True to drop these rows instead.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*columns | ColumnInputType | columns to explode | () |
index_column | ColumnInputType | None | optional name for an index column that tracks the position of each element within its original list | None |
ignore_empty_and_null | bool | If True, drops rows where the list is empty or null. If False (default), empty lists and null values each produce a single row with a null value. | False |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with exploded column |
Examples:
1 2 3 4 5 6 7 8 9 10 11 12 13 | |
╭─────────────┬──────────────┬───────────────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ List[Int64] ┆ List[String] ┆ List[Float64] │
╞═════════════╪══════════════╪═══════════════╡
│ [1] ┆ [a] ┆ [1] │
├╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ [2, 3] ┆ [b, c] ┆ [2, 2] │
╰─────────────┴──────────────┴───────────────╯
(Showing first 2 of 2 rows)
╭───────┬────────┬───────────────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ String ┆ List[Float64] │
╞═══════╪════════╪═══════════════╡
│ 1 ┆ a ┆ [1] │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ 2 ┆ b ┆ [2, 2] │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ 3 ┆ c ┆ [2, 2] │
╰───────┴────────┴───────────────╯
(Showing first 3 of 3 rows) Example with Null values and empty lists:
1 2 3 4 5 | |
╭───────┬─────────────┬──────────────╮
│ id ┆ values ┆ labels │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ List[Int64] ┆ List[String] │
╞═══════╪═════════════╪══════════════╡
│ 1 ┆ [1, 2] ┆ [a, b] │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ 2 ┆ [] ┆ [] │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ 3 ┆ None ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ 4 ┆ [3] ┆ [c] │
╰───────┴─────────────┴──────────────╯
(Showing first 4 of 4 rows)
╭───────┬────────┬────────╮
│ id ┆ values ┆ labels │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ String │
╞═══════╪════════╪════════╡
│ 1 ┆ 1 ┆ a │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 1 ┆ 2 ┆ b │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 2 ┆ None ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 3 ┆ None ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 4 ┆ 3 ┆ c │
╰───────┴────────┴────────╯
(Showing first 5 of 5 rows) Example with ignore_empty_and_null=True:
1 | |
╭───────┬────────┬────────╮
│ id ┆ values ┆ labels │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ String │
╞═══════╪════════╪════════╡
│ 1 ┆ 1 ┆ a │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 1 ┆ 2 ┆ b │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 4 ┆ 3 ┆ c │
╰───────┴────────┴────────╯
(Showing first 3 of 3 rows) Example with index_column to track element positions:
1 2 | |
╭───────┬────────╮
│ a ┆ idx │
│ --- ┆ --- │
│ Int64 ┆ UInt64 │
╞═══════╪════════╡
│ 1 ┆ 0 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 2 ┆ 1 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 3 ┆ 0 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 4 ┆ 1 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 3 ┆ 2 │
╰───────┴────────╯
(Showing first 5 of 5 rows) Source code in daft/dataframe/dataframe.py
4122 4123 4124 4125 4126 4127 4128 4129 4130 4131 4132 4133 4134 4135 4136 4137 4138 4139 4140 4141 4142 4143 4144 4145 4146 4147 4148 4149 4150 4151 4152 4153 4154 4155 4156 4157 4158 4159 4160 4161 4162 4163 4164 4165 4166 4167 4168 4169 4170 4171 4172 4173 4174 4175 4176 4177 4178 4179 4180 4181 4182 4183 4184 4185 4186 4187 4188 4189 4190 4191 4192 4193 4194 4195 4196 4197 4198 4199 4200 4201 4202 4203 4204 4205 4206 4207 4208 4209 4210 4211 4212 4213 4214 4215 4216 4217 4218 4219 4220 4221 4222 4223 4224 4225 4226 4227 4228 4229 4230 4231 4232 4233 4234 4235 4236 4237 4238 4239 4240 4241 4242 4243 4244 4245 4246 4247 4248 4249 4250 4251 4252 4253 4254 4255 4256 4257 4258 4259 4260 4261 4262 4263 4264 4265 4266 4267 4268 4269 | |
filter #
filter(predicate: Expression | str) -> DataFrame
Filters rows via a predicate expression, similar to SQL WHERE.
Alias for daft.DataFrame.where.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
predicate | Expression | expression that keeps row if evaluates to True. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Filtered DataFrame. |
Tip
See also .where(predicate)
Examples:
1 2 3 | |
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 2 ┆ 6 ┆ 8 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 ┆ 9 │
╰───────┴───────┴───────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
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groupby #
groupby(*group_by: ManyColumnsInputType) -> GroupedDataFrame
Performs a GroupBy on the DataFrame for aggregation.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*group_by | Union[str, Expression] | columns to group by | () |
Returns:
| Name | Type | Description |
|---|---|---|
GroupedDataFrame | GroupedDataFrame | DataFrame to Aggregate |
Examples:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 | |
╭────────┬─────────┬─────────┬────────┬────────╮
│ pet ┆ min_age ┆ max_age ┆ count ┆ name │
│ --- ┆ --- ┆ --- ┆ --- ┆ --- │
│ String ┆ Int64 ┆ Int64 ┆ UInt64 ┆ String │
╞════════╪═════════╪═════════╪════════╪════════╡
│ cat ┆ 1 ┆ 4 ┆ 2 ┆ Alex │
├╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ dog ┆ 2 ┆ 3 ┆ 2 ┆ Jordan │
╰────────┴─────────┴─────────┴────────┴────────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
4974 4975 4976 4977 4978 4979 4980 4981 4982 4983 4984 4985 4986 4987 4988 4989 4990 4991 4992 4993 4994 4995 4996 4997 4998 4999 5000 5001 5002 5003 5004 5005 5006 5007 5008 5009 5010 5011 5012 5013 5014 5015 | |
intersect #
Returns the intersection of two DataFrames.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | DataFrame to intersect with | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with the intersection of the two DataFrames |
Examples:
1 2 3 4 5 6 | |
╭───────┬───────╮
│ a ┆ b │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
╰───────┴───────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
5230 5231 5232 5233 5234 5235 5236 5237 5238 5239 5240 5241 5242 5243 5244 5245 5246 5247 5248 5249 5250 5251 5252 5253 5254 5255 5256 5257 5258 5259 5260 5261 | |
intersect_all #
Returns the intersection of two DataFrames, including duplicates.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | DataFrame to intersect with | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with the intersection of the two DataFrames, including duplicates |
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ a ┆ b │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 6 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 6 │
╰───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
5263 5264 5265 5266 5267 5268 5269 5270 5271 5272 5273 5274 5275 5276 5277 5278 5279 5280 5281 5282 5283 5284 5285 5286 5287 5288 5289 5290 5291 5292 5293 5294 | |
into_batches #
into_batches(batch_size: int) -> DataFrame
Splits or coalesces DataFrame to partitions of size batch_size.
Note
Batch sizing is performed on a best-effort basis. The heuristic is to emit a batch when we have enough rows to fill batch_size * 0.8 rows. This approach prioritizes processing efficiency over uniform batch sizes, especially when using the Ray Runner, as batches can be distributed over the cluster. The exception to this is that the last batch will be the remainder of the total number of rows in the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
batch_size | int | number of target rows per partition. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Dataframe with |
Examples:
1 2 3 4 5 | |
Source code in daft/dataframe/dataframe.py
3723 3724 3725 3726 3727 3728 3729 3730 3731 3732 3733 3734 3735 3736 3737 3738 3739 3740 3741 3742 3743 3744 3745 3746 3747 3748 3749 3750 | |
into_partitions #
into_partitions(num: int) -> DataFrame
Splits or coalesces DataFrame to num partitions. Order is preserved.
This will naively greedily split partitions in a round-robin fashion to hit the targeted number of partitions. The number of rows/size in a given partition is not taken into account during the splitting.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
num | int | number of target partitions. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Dataframe with |
Source code in daft/dataframe/dataframe.py
3702 3703 3704 3705 3706 3707 3708 3709 3710 3711 3712 3713 3714 3715 3716 3717 3718 3719 3720 3721 | |
iter_partitions #
iter_partitions(results_buffer_size: int | None | Literal['num_cpus'] = 'num_cpus') -> Iterator[Union[MicroPartition, ObjectRef]]
Begin executing this dataframe and return an iterator over the partitions.
Each partition will be returned as a daft.recordbatch object (if using Python runner backend) or a ray ObjectRef (if using Ray runner backend).
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
results_buffer_size | int | None | Literal['num_cpus'] | how many partitions to allow in the results buffer (defaults to the total number of CPUs available on the machine). | 'num_cpus' |
A quick note on configuring asynchronous/parallel execution using results_buffer_size.
The results_buffer_size kwarg controls how many results Daft will allow to be in the buffer while iterating. Once this buffer is filled, Daft will not run any more work until some partition is consumed from the buffer.
- Increasing this value means the iterator will consume more memory and CPU resources but have higher throughput
- Decreasing this value means the iterator will consume lower memory and CPU resources, but have lower throughput
- Setting this value to
Nonemeans the iterator will consume as much resources as it deems appropriate per-iteration
The default value is the total number of CPUs available on the current machine.
Returns:
| Type | Description |
|---|---|
Iterator[Union[MicroPartition, ObjectRef]] | Iterator[Union[MicroPartition, ray.ObjectRef]]: An iterator over the partitions of the DataFrame. |
Iterator[Union[MicroPartition, ObjectRef]] | Each partition is a MicroPartition object (if using Python runner backend) or a ray ObjectRef |
Iterator[Union[MicroPartition, ObjectRef]] | (if using Ray runner backend). |
Examples:
1 2 3 4 5 6 7 | |
MicroPartition with 3 rows:
TableState: Loaded. 1 tables
╭───────┬────────╮
│ foo ┆ bar │
│ --- ┆ --- │
│ Int64 ┆ String │
╞═══════╪════════╡
│ 1 ┆ a │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 2 ┆ b │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 3 ┆ c │
╰───────┴────────╯
Statistics: missing Source code in daft/dataframe/dataframe.py
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iter_rows #
iter_rows(results_buffer_size: int | None | Literal['num_cpus'] = 'num_cpus', column_format: Literal['python', 'arrow'] = 'python') -> Iterator[dict[str, Any]]
Return an iterator of rows for this dataframe.
Each row will be a Python dictionary of the form { "key" : value, ...}. If you are instead looking to iterate over entire partitions of data, see df.iter_partitions().
By default, Daft will convert the columns to Python lists for easy consumption. Datatypes with Python equivalents will be converted accordingly, e.g. timestamps to datetime, tensors to numpy arrays. For nested data such as List or Struct arrays, however, this can be expensive. You may wish to set column_format to "arrow" such that the nested data is returned as Arrow scalars.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
results_buffer_size | int | None | Literal['num_cpus'] | how many partitions to allow in the results buffer (defaults to the total number of CPUs available on the machine). | 'num_cpus' |
column_format | Literal['python', 'arrow'] | the format of the columns to iterate over. One of "python" or "arrow". Defaults to "python". | 'python' |
A quick note on configuring asynchronous/parallel execution using results_buffer_size.
The results_buffer_size kwarg controls how many results Daft will allow to be in the buffer while iterating. Once this buffer is filled, Daft will not run any more work until some partition is consumed from the buffer.
- Increasing this value means the iterator will consume more memory and CPU resources but have higher throughput
- Decreasing this value means the iterator will consume lower memory and CPU resources, but have lower throughput
- Setting this value to
Nonemeans the iterator will consume as much resources as it deems appropriate per-iteration
The default value is the total number of CPUs available on the current machine.
Returns:
| Type | Description |
|---|---|
Iterator[dict[str, Any]] | Iterator[dict[str, Any]]: An iterator over the rows of the DataFrame, where each row is a dictionary |
Iterator[dict[str, Any]] | mapping column names to values. |
Examples:
1 2 3 4 5 | |
{'foo': 1, 'bar': 'a'}
{'foo': 2, 'bar': 'b'}
{'foo': 3, 'bar': 'c'} Tip
See also df.iter_partitions(): iterator over entire partitions instead of single rows
Source code in daft/dataframe/dataframe.py
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join #
join(other: DataFrame, on: list[ColumnInputType] | ColumnInputType | None = None, left_on: list[ColumnInputType] | ColumnInputType | None = None, right_on: list[ColumnInputType] | ColumnInputType | None = None, how: Literal['inner', 'left', 'right', 'outer', 'anti', 'semi', 'cross'] = 'inner', strategy: Literal['hash', 'sort_merge', 'broadcast'] | None = None, prefix: str | None = None, suffix: str | None = None) -> DataFrame
Column-wise join of the current DataFrame with an other DataFrame, similar to a SQL JOIN.
If the two DataFrames have duplicate non-join key column names, "right." will be prepended to the conflicting right columns. You can change the behavior by passing either (or both) prefix or suffix to the function. If prefix is passed, it will be prepended to the conflicting right columns. If suffix is passed, it will be appended to the conflicting right columns.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | the right DataFrame to join on. | required |
on | Optional[Union[List[ColumnInputType], ColumnInputType]] | key or keys to join on [use if the keys on the left and right side match.]. Defaults to None. | None |
left_on | Optional[Union[List[ColumnInputType], ColumnInputType]] | key or keys to join on left DataFrame. Defaults to None. | None |
right_on | Optional[Union[List[ColumnInputType], ColumnInputType]] | key or keys to join on right DataFrame. Defaults to None. | None |
how | str | what type of join to perform; currently "inner", "left", "right", "outer", "anti", "semi", and "cross" are supported. Defaults to "inner". | 'inner' |
strategy | Optional[str] | The join strategy (algorithm) to use; currently "hash", "sort_merge", "broadcast", and None are supported, where None chooses the join strategy automatically during query optimization. The default is None. | None |
suffix | Optional[str] | Suffix to add to the column names in case of a name collision. Defaults to "". | None |
prefix | Optional[str] | Prefix to add to the column names in case of a name collision. Defaults to "right.". | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Joined DataFrame. |
Raises:
| Type | Description |
|---|---|
ValueError | if |
ValueError | if |
Note
Although self joins are supported, we currently duplicate the logical plan for the right side and recompute the entire tree. Caching for this is on the roadmap.
Examples:
1 2 3 4 5 6 | |
╭────────┬───────┬─────────╮
│ a ┆ b ┆ right.b │
│ --- ┆ --- ┆ --- │
│ String ┆ Int64 ┆ Int64 │
╞════════╪═══════╪═════════╡
│ x ┆ 2 ┆ 20 │
├╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ y ┆ 3 ┆ 30 │
╰────────┴───────┴─────────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
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join_asof #
join_asof(other: DataFrame, *, on: ColumnInputType | None = None, left_on: ColumnInputType | None = None, right_on: ColumnInputType | None = None, by: list[ColumnInputType] | ColumnInputType | None = None, left_by: list[ColumnInputType] | ColumnInputType | None = None, right_by: list[ColumnInputType] | ColumnInputType | None = None, strategy: Literal['backward', 'forward', 'nearest'] = 'backward', prefix: str | None = None, suffix: str | None = None, _assume_sorted_and_aligned: bool = False) -> DataFrame
Point-in-time (asof) join: each left row matches the nearest right row according to the chosen strategy.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | Right-hand DataFrame (e.g. feature table). | required |
on | ColumnInputType | None | Asof key column when it has the same name on both sides. Exactly one column. | None |
left_on | ColumnInputType | None | Asof key on the left when names differ. Exactly one column; use with | None |
right_on | ColumnInputType | None | Asof key on the right when names differ. Exactly one column; use with | None |
by | list[ColumnInputType] | ColumnInputType | None | Equality key column(s) with the same name on both sides (entity / group columns). | None |
left_by | list[ColumnInputType] | ColumnInputType | None | Equality keys on the left when names differ; use with | None |
right_by | list[ColumnInputType] | ColumnInputType | None | Equality keys on the right when names differ; use with | None |
strategy | Literal['backward', 'forward', 'nearest'] | Match strategy. | 'backward' |
_assume_sorted_and_aligned | bool | Asserts that both tables have the same number of partitions with identical boundaries, and that rows within each partition are sorted ascending by the on-key. Also requires | False |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Left-join-shaped result (every left row kept; unmatched right columns are null). |
Raises:
| Type | Description |
|---|---|
ValueError | if |
ValueError | if |
ValueError | if both |
ValueError | if only one of |
ValueError | if |
Examples:
1 2 3 4 5 6 7 8 9 10 | |
╭────────┬───────────┬─────────╮
│ entity ┆ timestamp ┆ value │
│ --- ┆ --- ┆ --- │
│ String ┆ Int64 ┆ Float64 │
╞════════╪═══════════╪═════════╡
│ A ┆ 10 ┆ 2 │
├╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ A ┆ 11 ┆ 3 │
├╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┤
│ B ┆ 10 ┆ 5 │
╰────────┴───────────┴─────────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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limit #
limit(num: int) -> DataFrame
Limits the rows in the DataFrame to the first N rows, similar to a SQL LIMIT.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
num | int | maximum rows to allow. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Limited DataFrame |
Examples:
1 2 3 4 | |
╭───────╮
│ x │
│ --- │
│ Int64 │
╞═══════╡
│ 1 │
├╌╌╌╌╌╌╌┤
│ 2 │
├╌╌╌╌╌╌╌┤
│ 3 │
├╌╌╌╌╌╌╌┤
│ 4 │
├╌╌╌╌╌╌╌┤
│ 5 │
╰───────╯
(Showing first 5 of 5 rows) Source code in daft/dataframe/dataframe.py
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max #
max(*cols: ColumnInputType) -> DataFrame
Performs a global max on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to max | () |
Returns: DataFrame: Globally aggregated max. Should be a single row.
Examples:
1 2 3 4 | |
╭───────╮
│ col_a │
│ --- │
│ Int64 │
╞═══════╡
│ 3 │
╰───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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mean #
mean(*cols: ColumnInputType) -> DataFrame
Performs a global mean on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to mean | () |
Returns: DataFrame: Globally aggregated mean. Should be a single row.
Examples:
1 2 3 4 | |
╭─────────╮
│ col_a │
│ --- │
│ Float64 │
╞═════════╡
│ 2 │
╰─────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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melt #
melt(ids: ManyColumnsInputType, values: ManyColumnsInputType = [], variable_name: str = 'variable', value_name: str = 'value') -> DataFrame
Alias for unpivot.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
ids | ManyColumnsInputType | Columns to keep as identifiers | required |
values | Optional[ManyColumnsInputType] | Columns to unpivot. If not specified, all columns except ids will be unpivoted. | [] |
variable_name | Optional[str] | Name of the variable column. Defaults to "variable". | 'variable' |
value_name | Optional[str] | Name of the value column. Defaults to "value". | 'value' |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Unpivoted DataFrame |
Examples:
1 2 3 4 5 6 7 8 9 10 11 | |
╭───────┬────────┬───────────╮
│ year ┆ month ┆ inventory │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ String ┆ Int64 │
╞═══════╪════════╪═══════════╡
│ 2020 ┆ Jan ┆ 10 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2020 ┆ Feb ┆ 20 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2021 ┆ Jan ┆ 30 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2021 ┆ Feb ┆ 40 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2022 ┆ Jan ┆ 50 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2022 ┆ Feb ┆ 60 │
╰───────┴────────┴───────────╯
(Showing first 6 of 6 rows) Tip
See also unpivot
Source code in daft/dataframe/dataframe.py
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min #
min(*cols: ColumnInputType) -> DataFrame
Performs a global min on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to min | () |
Returns: DataFrame: Globally aggregated min. Should be a single row.
Examples:
1 2 3 4 | |
╭───────╮
│ col_a │
│ --- │
│ Int64 │
╞═══════╡
│ 1 │
╰───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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num_partitions #
num_partitions() -> int | None
Returns the number of partitions that will be used to execute this DataFrame.
The query optimizer may change the partitioning strategy. This method runs the optimizer and then inspects the resulting physical plan scheduler to determine how many partitions the execution will use.
Returns:
| Name | Type | Description |
|---|---|---|
int | int | None | The number of partitions in the optimized physical execution plan. |
Examples:
1 2 3 4 5 6 7 8 9 10 11 12 13 | |
1
10 Source code in daft/dataframe/dataframe.py
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offset #
offset(num: int) -> DataFrame
Returns a new DataFrame by skipping the first N rows, similar to a SQL Offset.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
num | int | the number of rows to skip | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A new DataFrame by skipping the first |
Examples:
1 2 3 4 | |
╭───────╮
│ x │
│ --- │
│ Int64 │
╞═══════╡
│ 2 │
├╌╌╌╌╌╌╌┤
│ 3 │
├╌╌╌╌╌╌╌┤
│ 4 │
├╌╌╌╌╌╌╌┤
│ 5 │
├╌╌╌╌╌╌╌┤
│ 6 │
╰───────╯
(Showing first 5 of 5 rows) Source code in daft/dataframe/dataframe.py
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pipe #
pipe(function: Callable[Concatenate[DataFrame, P], T], *args: args, **kwargs: kwargs) -> T
Apply the function to this DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
function | Callable[Concatenate[DataFrame, P], T] | Function to apply. | required |
*args | args | Positional arguments to pass to the function. | () |
**kwargs | kwargs | Keyword arguments to pass to the function. | {} |
Returns:
| Type | Description |
|---|---|
T | Result of applying the function on this DataFrame. |
Examples:
1 2 3 4 5 6 7 8 | |
╭───────╮
│ x │
│ --- │
│ Int64 │
╞═══════╡
│ 1 │
├╌╌╌╌╌╌╌┤
│ 4 │
├╌╌╌╌╌╌╌┤
│ 9 │
╰───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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pivot #
pivot(group_by: ManyColumnsInputType, pivot_col: ColumnInputType, value_col: ColumnInputType, agg_fn: str, names: list[str] | None = None) -> DataFrame
Pivots a column of the DataFrame and performs an aggregation on the values.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
group_by | ManyColumnsInputType | columns to group by | required |
pivot_col | Union[str, Expression] | column to pivot | required |
value_col | Union[str, Expression] | column to aggregate | required |
agg_fn | str | aggregation function to apply | required |
names | Optional[List[str]] | names of the pivoted columns | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with pivoted columns |
Note
You may wish to provide a list of distinct values to pivot on, which is more efficient as it avoids a distinct operation. Without this list, Daft will perform a distinct operation on the pivot column to determine the unique values to pivot on.
Examples:
1 2 3 4 5 6 7 8 9 10 11 12 | |
╭─────────┬─────────┬───────╮
│ version ┆ windows ┆ macos │
│ --- ┆ --- ┆ --- │
│ String ┆ Int64 ┆ Int64 │
╞═════════╪═════════╪═══════╡
│ 3.8 ┆ None ┆ 300 │
├╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3.9 ┆ 250 ┆ 150 │
╰─────────┴─────────┴───────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
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product #
product(*cols: ColumnInputType) -> DataFrame
Performs a global product on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to product | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Globally aggregated products. Should be a single row. |
Examples:
1 2 3 4 | |
╭───────╮
│ col_a │
│ --- │
│ Int64 │
╞═══════╡
│ 6 │
╰───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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repartition #
repartition(num: int | None, *partition_by: ColumnInputType) -> DataFrame
Repartitions DataFrame to num partitions.
If columns are passed in, then DataFrame will be repartitioned by those, otherwise random repartitioning will occur.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
num | Optional[int] | Number of target partitions; if None, the number of partitions will not be changed. | required |
*partition_by | Union[str, Expression] | Optional columns to partition by. | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Repartitioned DataFrame. |
This function will globally shuffle your data, which is potentially a very expensive operation.
If instead you merely wish to "split" or "coalesce" partitions to obtain a target number of partitions, you mean instead wish to consider using DataFrame.into_partitions which avoids shuffling of data in favor of splitting/coalescing adjacent partitions where appropriate.
Examples:
1 2 3 | |
Source code in daft/dataframe/dataframe.py
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sample #
sample(fraction: float | None = None, size: int | None = None, with_replacement: bool = False, seed: int | None = None) -> DataFrame
Samples rows from the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
fraction | Optional[float] | fraction of rows to sample (between 0.0 and 1.0). Must specify either | None |
size | Optional[int] | exact number of rows to sample. Must specify either | None |
with_replacement | bool | whether to sample with replacement. Defaults to False. | False |
seed | Optional[int] | random seed. Defaults to None. | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with sampled rows. |
Examples:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 | |
Source code in daft/dataframe/dataframe.py
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schema #
schema() -> Schema
Returns the Schema of the DataFrame, which provides information about each column, as a Python object.
Returns:
| Name | Type | Description |
|---|---|---|
Schema | Schema | schema of the DataFrame |
Examples:
1 2 3 4 | |
╭─────────────┬────────╮
│ Column Name ┆ DType │
╞═════════════╪════════╡
│ x ┆ Int64 │
├╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ y ┆ String │
╰─────────────┴────────╯ Source code in daft/dataframe/dataframe.py
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select #
select(*columns: ColumnInputType, **projections: Expression) -> DataFrame
Creates a new DataFrame from the provided expressions, similar to a SQL SELECT.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*columns | Union[str, Expression] | columns to select from the current DataFrame | () |
**projections | Expression | additional projections in kwarg format. | {} |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | new DataFrame that will select the passed in columns |
Examples:
1 2 3 4 | |
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1 ┆ 4 ┆ 8 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 9 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 ┆ 10 │
╰───────┴───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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show #
show(n: int = 8, format: PreviewFormat | None = None, verbose: bool | None = None, max_width: int | None = None, align: PreviewAlign | None = None, columns: list[PreviewColumn] | None = None) -> None
Executes enough of the DataFrame in order to display the first n rows.
If IPython is installed, this will use IPython's display utility to pretty-print in a notebook/REPL environment. Otherwise, this will fall back onto a naive Python print.
If no format is given, then daft's truncating preview format is used. - The output is a 'fancy' table with rounded corners. - Headers contain the column's data type. - Columns are truncated to 30 characters. - The table's overall width is limited to 10 columns. Default values can be overridden with environment variables: - DAFT_SHOW_FORMAT - DAFT_SHOW_VERBOSE - DAFT_SHOW_MAX_WIDTH - DAFT_SHOW_ALIGN
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
n | int | number of rows to show. Defaults to 8. | 8 |
format | PreviewFormat | the box-drawing format e.g. "fancy" or "markdown". | None |
verbose | bool | if True, headers include the column's data type. | None |
max_width | int | None | global max column width | None |
align | PreviewAlign | global column align | None |
columns | list[PreviewColumn] | column overrides | None |
Note
This call is blocking and will execute the DataFrame when called
Examples:
1 2 3 4 5 6 | |
Usage
- If columns are given, their length MUST match the schema.
- If columns are given, their settings override any global settings.
Source code in daft/dataframe/dataframe.py
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shuffle #
shuffle(seed: int | None = None) -> DataFrame
Randomly reorders rows of the DataFrame.
This is analogous to shuffle operation in the Hugging Face datasets library.
Note
This performs a global sort and is expensive. For randomly redistributing rows across partitions see :meth:DataFrame.repartition with no partition_by (random partition shuffle).
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
seed | int | None | Optional RNG seed passed to | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A new DataFrame with rows in random order. |
Source code in daft/dataframe/dataframe.py
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skew #
skew(*cols: ColumnInputType) -> DataFrame
Performs a global skew on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to compute skewness for | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Globally aggregated skewness. Should be a single row. |
Note
Daft uses the biased (population) skewness formula, which is equivalent to scipy.stats.skew(bias=True). This differs from pandas' default DataFrame.skew(), which uses the adjusted Fisher-Pearson (sample) formula. For small samples, the two formulas can produce meaningfully different results.
Examples:
1 2 3 4 | |
╭─────────╮
│ col_a │
│ --- │
│ Float64 │
╞═════════╡
│ 0 │
╰─────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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skip_existing #
skip_existing(existing_path: str | Path | list[str | Path], key_column: str | list[str], file_format: str | FileFormat, io_config: IOConfig | None = None, num_workers: int = 4, cpus_per_worker: float = 0.5, keys_load_batch_size: int = 100000, max_concurrency_per_worker: int = 1, filter_batch_size: int = 10000, **reader_args: Any) -> DataFrame
Filter out rows whose key(s) already exist in existing data (i.e., already processed rows).
This method reads existing data from the given path(s), builds a Ray actor-backed distributed key filter from the existing key columns, and filters the current DataFrame to only include rows whose key(s) are not present in the existing data. This is useful for incremental data processing pipelines where you want to avoid re-processing data that has already been written.
Missing paths are treated permissively: if none of the provided paths exist, the current DataFrame is returned unchanged; if only some paths exist, Daft logs a warning and continues with the existing subset.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
existing_path | str | Path | list[str | Path] | Path or list of paths to the existing data directory/file(s). | required |
key_column | str | list[str] | Column name(s) to use as the key for matching. Can be a single column name or a list of column names for composite keys. | required |
file_format | str | FileFormat | Format of the existing data files. Supported formats are Parquet, CSV, and JSON/JSONL/NDJSON. | required |
io_config | IOConfig | None | IO configuration for reading the existing data. | None |
num_workers | int | Number of Ray actors to spawn for key filtering. Each actor holds a shard of existing keys and filters incoming partitions in parallel. Higher values increase parallelism and typically reduce per-actor memory usage. | 4 |
cpus_per_worker | float | Number of CPUs to allocate per Ray actor. | 0.5 |
keys_load_batch_size | int | Batch size when loading keys from existing data into actors. | 100000 |
max_concurrency_per_worker | int | Maximum concurrency for per-actor operations. | 1 |
filter_batch_size | int | Batch size for the key filter operation. Controls how many rows are sent to the key filter actors per RPC call. Larger values reduce RPC overhead but increase memory usage proportionally across all concurrent tasks (total memory ≈ num_tasks × filter_batch_size × avg_key_size). For lightweight keys (int, short string), 10000-50000 works well. For large keys (URLs, long strings), keep this lower to avoid excessive memory usage. Defaults to 10000. | 10000 |
**reader_args | Any | Additional keyword arguments forwarded to the underlying reader for | {} |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A new DataFrame with rows filtered to exclude those whose keys exist in the existing data. |
Raises:
| Type | Description |
|---|---|
ValueError | If key columns are invalid, paths are empty, or parameters are out of range. |
RuntimeError | If the existing data cannot be read during execution or key filter resources cannot be allocated. |
Examples:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | |
[2, 4] Source code in daft/dataframe/dataframe.py
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sort #
sort(by: ColumnInputType | list[ColumnInputType], desc: bool | list[bool] = False, nulls_first: bool | list[bool] | None = None) -> DataFrame
Sorts DataFrame globally.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
by | Union[ColumnInputType, List[ColumnInputType]] | column to sort by. Can be | required |
desc | Union[bool, List[bool]) | Sort by descending order. Defaults to False. | False |
nulls_first | Union[bool, List[bool]) | Sort by nulls first. Defaults to nulls being treated as the greatest value. | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Sorted DataFrame. |
Note
- Since this a global sort, this requires an expensive repartition which can be quite slow.
- Supports multicolumn sorts and can have unique
descendingandnulls_firstflags per column.
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ x ┆ y │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 2 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1 ┆ 5 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
╰───────┴───────╯
(Showing first 3 of 3 rows) You can also sort by multiple columns, and specify the 'descending' flag for each column:
1 2 3 | |
╭───────┬───────╮
│ x ┆ y │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 2 ┆ 6 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 8 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1 ┆ 9 │
╰───────┴───────╯
(Showing first 4 of 4 rows) You can also specify null positioning (first/last) for each column
1 2 3 | |
╭───────┬───────╮
│ x ┆ y │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ None ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 6 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 8 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1 ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1 ┆ 9 │
╰───────┴───────╯
(Showing first 5 of 5 rows) Source code in daft/dataframe/dataframe.py
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stddev #
stddev(*cols: ColumnInputType, ddof: int = 1) -> DataFrame
Performs a global standard deviation on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to stddev | () |
ddof | int | Delta degrees of freedom used in the denominator | 1 |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Globally aggregated standard deviation. Should be a single row. |
Examples:
1 2 3 4 | |
╭─────────╮
│ col_a │
│ --- │
│ Float64 │
╞═════════╡
│ 1 │
╰─────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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sum #
sum(*cols: ManyColumnsInputType) -> DataFrame
Performs a global sum on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to sum | () |
Returns: DataFrame: Globally aggregated sums. Should be a single row.
Examples:
1 2 3 4 | |
╭───────╮
│ col_a │
│ --- │
│ Int64 │
╞═══════╡
│ 6 │
╰───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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summarize #
summarize() -> DataFrame
Returns column statistics for the DataFrame.
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | new DataFrame with the computed column statistics. |
Examples:
1 2 3 | |
╭────────┬────────┬────────┬────────────┬────────┬─────────────┬───────────────────────╮
│ column ┆ type ┆ min ┆ … ┆ count ┆ count_nulls ┆ approx_count_distinct │
│ --- ┆ --- ┆ --- ┆ ┆ --- ┆ --- ┆ --- │
│ String ┆ String ┆ String ┆ (1 hidden) ┆ UInt64 ┆ UInt64 ┆ UInt64 │
╞════════╪════════╪════════╪════════════╪════════╪═════════════╪═══════════════════════╡
│ x ┆ Int64 ┆ 1 ┆ … ┆ 3 ┆ 0 ┆ 3 │
├╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ y ┆ Int64 ┆ 4 ┆ … ┆ 3 ┆ 0 ┆ 3 │
├╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌╌┤
│ z ┆ Int64 ┆ 7 ┆ … ┆ 3 ┆ 0 ┆ 3 │
╰────────┴────────┴────────┴────────────┴────────┴─────────────┴───────────────────────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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to_arrow #
to_arrow() -> Table
Converts the current DataFrame to a pyarrow Table.
If results have not computed yet, collect will be called.
Returns:
| Type | Description |
|---|---|
Table | pyarrow.Table: pyarrow Table converted from a Daft DataFrame |
Note
This call is blocking and will execute the DataFrame when called
Examples:
1 2 3 4 | |
pyarrow.Table
a: int64
b: int64
----
a: [[1,2,3]]
b: [[4,5,6]] Tip
See also DataFrame.to_arrow_iter() for a streaming iterator over the rows of the DataFrame as Arrow RecordBatches.
Source code in daft/dataframe/dataframe.py
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to_arrow_iter #
to_arrow_iter(results_buffer_size: int | None | Literal['num_cpus'] = 'num_cpus') -> Iterator[RecordBatch]
Return an iterator of pyarrow recordbatches for this dataframe.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
results_buffer_size | int | None | Literal['num_cpus'] | how many partitions to allow in the results buffer (defaults to the total number of CPUs available on the machine). | 'num_cpus' |
Note: A quick note on configuring asynchronous/parallel execution using results_buffer_size. The results_buffer_size kwarg controls how many results Daft will allow to be in the buffer while iterating. Once this buffer is filled, Daft will not run any more work until some partition is consumed from the buffer. * Increasing this value means the iterator will consume more memory and CPU resources but have higher throughput * Decreasing this value means the iterator will consume lower memory and CPU resources, but have lower throughput * Setting this value to None means the iterator will consume as much resources as it deems appropriate per-iteration The default value is the total number of CPUs available on the current machine.
Returns:
| Type | Description |
|---|---|
Iterator[RecordBatch] | Iterator[pyarrow.RecordBatch]: An iterator over the RecordBatches of the DataFrame. |
Examples:
1 2 3 4 5 | |
pyarrow.RecordBatch
foo: int64
bar: large_string
----
foo: [1,2,3]
bar: ["a","b","c"] Source code in daft/dataframe/dataframe.py
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to_dask_dataframe #
to_dask_dataframe(meta: Union[DataFrame, Series[Any], dict[str, Any], Iterable[Any], tuple[Any], None] = None) -> DataFrame
Converts the current Daft DataFrame to a Dask DataFrame.
The returned Dask DataFrame will use Dask-on-Ray to execute operations on a Ray cluster.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
meta | Union[DataFrame, Series[Any], dict[str, Any], Iterable[Any], tuple[Any], None] | An empty pandas DataFrameor Series that matches the dtypes and column names of the stream. This metadata is necessary for many algorithms in dask dataframe to work. For ease of use, some alternative inputs are also available. Instead of a DataFrame, a dict of | None |
Returns:
| Type | Description |
|---|---|
DataFrame | dask.DataFrame: A Dask DataFrame stored on a Ray cluster. |
Note
This function can only work if Daft is running using the RayRunner.
Examples:
1 2 3 4 | |
Source code in daft/dataframe/dataframe.py
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to_pandas #
to_pandas(coerce_temporal_nanoseconds: bool = False) -> DataFrame
Converts the current DataFrame to a pandas DataFrame.
If results have not computed yet, collect will be called.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
coerce_temporal_nanoseconds | bool | Whether to coerce temporal columns to nanoseconds. Only applicable to pandas version >= 2.0 and pyarrow version >= 13.0.0. Defaults to False. See | False |
Returns:
| Type | Description |
|---|---|
DataFrame | pandas.DataFrame: pandas DataFrame converted from a Daft DataFrame |
Note
This call is blocking and will execute the DataFrame when called
Examples:
1 2 3 4 | |
a b
0 1 4
1 2 5
2 3 6 Source code in daft/dataframe/dataframe.py
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to_pydict #
to_pydict(maps_as_pydicts: Literal['lossy', 'strict'] | None = None) -> dict[str, list[Any]]
Converts the current DataFrame to a python dictionary. The dictionary contains Python lists of Python objects for each column.
If results have not computed yet, collect will be called.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
maps_as_pydicts | Literal['lossy', 'strict'] | None | If None (default), Map values are converted to association lists ( | None |
Returns:
| Type | Description |
|---|---|
dict[str, list[Any]] | dict[str, list[Any]]: python dict converted from a Daft DataFrame |
Note
This call is blocking and will execute the DataFrame when called
Examples:
1 2 3 | |
{'a': [1, 2, 3, 4], 'b': [2, 4, 3, 1]} Tip
See also DataFrame.to_pylist() for a convenience method that converts the DataFrame to a list of Python dict objects.
Source code in daft/dataframe/dataframe.py
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to_pylist #
to_pylist(maps_as_pydicts: Literal['lossy', 'strict'] | None = None) -> list[Any]
Converts the current Dataframe into a python list.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
maps_as_pydicts | Literal['lossy', 'strict'] | None | If None (default), Map values are converted to association lists ( | None |
Returns:
| Type | Description |
|---|---|
list[Any] | List[dict[str, Any]]: List of python dict objects. |
Warning
This is a convenience method over DataFrame.iter_rows(). Users should prefer using .iter_rows() directly instead for lower memory utilization if they are streaming rows out of a DataFrame and don't require full materialization of the Python list.
Examples:
1 2 3 4 | |
[{'a': 1, 'b': 2}, {'a': 2, 'b': 4}, {'a': 3, 'b': 3}, {'a': 4, 'b': 1}] See also
df.iter_rows(): streaming iterator over individual rows in a DataFrame
Source code in daft/dataframe/dataframe.py
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to_ray_dataset #
to_ray_dataset() -> DataSet
Converts the current DataFrame to a Ray Dataset which is useful for running distributed ML model training in Ray.
Returns:
| Type | Description |
|---|---|
DataSet | ray.data.dataset.DataSet: Ray dataset |
Examples:
1 2 3 | |
Note
This function requires Ray to be installed. It works with any Daft runner - when using the native runner, partitions are converted to Arrow tables locally and then handed to Ray.
Source code in daft/dataframe/dataframe.py
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to_torch_iter_dataset #
to_torch_iter_dataset(shard_strategy: Literal['file'] | None = None, world_size: int | None = None, rank: int | None = None) -> IterableDataset
Convert the current DataFrame into a Torch IterableDataset <https://pytorch.org/docs/stable/data.html#torch.utils.data.IterableDataset>__ for use with PyTorch.
Begins execution of the DataFrame if it is not yet executed.
Items will be returned in pydict format: a dict of {"column name": value} for each row in the data.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
shard_strategy | Optional[Literal['file']] | Strategy to use for sharding the dataset. Currently only "file" is supported. | None |
world_size | Optional[int] | Total number of workers for sharding. Required if shard_strategy is specified. | None |
rank | Optional[int] | Rank of current worker for sharding. Required if shard_strategy is specified. | None |
Returns:
| Type | Description |
|---|---|
IterableDataset | torch.utils.data.IterableDataset: A PyTorch IterableDataset containing the data from the DataFrame. |
Examples:
1 2 3 4 5 | |
[{'x': tensor([1]), 'y': tensor([4])}, {'x': tensor([2]), 'y': tensor([5])}, {'x': tensor([3]), 'y': tensor([6])}] Note
The produced dataset is meant to be used with the single-process DataLoader, and does not support data sharding hooks for multi-process data loading.
Do keep in mind that Daft is already using multithreading or multiprocessing under the hood to compute the data stream that feeds this dataset.
Tip
This method returns results locally. For distributed training, you may want to use DataFrame.to_ray_dataset().
Source code in daft/dataframe/dataframe.py
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to_torch_map_dataset #
to_torch_map_dataset(shard_strategy: Literal['file'] | None = None, world_size: int | None = None, rank: int | None = None) -> Dataset
Convert the current DataFrame into a map-style Torch Dataset for use with PyTorch.
This method will materialize the entire DataFrame and block on completion.
Items will be returned in pydict format: a dict of {"column name": value} for each row in the data.
Note
If you do not need random access, you may get better performance out of an IterableDataset, which streams data items in as soon as they are ready and does not block on full materialization.
Tip
This method returns results locally. For distributed training, you may want to use DataFrame.to_ray_dataset().
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
shard_strategy | Optional[Literal['file']] | Strategy to use for sharding the dataset. Currently only "file" is supported. | None |
world_size | Optional[int] | Total number of workers for sharding. Required if shard_strategy is specified. | None |
rank | Optional[int] | Rank of current worker for sharding. Required if shard_strategy is specified. | None |
Returns:
| Type | Description |
|---|---|
Dataset | torch.utils.data.Dataset: A PyTorch Dataset containing the data from the DataFrame. |
Note
The produced dataset is meant to be used with the single-process DataLoader, and does not support data sharding hooks for multi-process data loading.
Examples:
1 2 3 4 | |
Tip
This method returns results locally. For distributed training, you may want to use DataFrame.to_ray_dataset().
Source code in daft/dataframe/dataframe.py
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transform #
Apply a function that takes and returns a DataFrame.
Allow splitting your transformation into different units of work (functions) while preserving the syntax for chaining transformations.
Examples:
1 2 3 4 5 6 7 8 9 10 | |
╭───────╮
│ col_a │
│ --- │
│ Int64 │
╞═══════╡
│ 8 │
├╌╌╌╌╌╌╌┤
│ 12 │
├╌╌╌╌╌╌╌┤
│ 16 │
├╌╌╌╌╌╌╌┤
│ 20 │
╰───────╯
(Showing first 4 of 4 rows) Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
func | Callable[..., DataFrame] | A function that takes and returns a DataFrame. | required |
*args | Any | Positional arguments to pass to func. | () |
**kwargs | Any | Keyword arguments to pass to func. | {} |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Transformed DataFrame. |
Source code in daft/dataframe/dataframe.py
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union #
Returns the distinct union of two DataFrames.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | The DataFrame to union with this one. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A new DataFrame containing the distinct rows from both DataFrames. |
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ x ┆ y │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 4 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 5 ┆ 8 │
╰───────┴───────╯
(Showing first 5 of 5 rows) Source code in daft/dataframe/dataframe.py
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union_all #
Returns the union of two DataFrames, including duplicates.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | The DataFrame to union with this one. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A new DataFrame containing all rows from both DataFrames, including duplicates. |
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ x ┆ y │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
╰───────┴───────╯
(Showing first 6 of 6 rows) Source code in daft/dataframe/dataframe.py
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union_all_by_name #
Returns the union of two DataFrames, including duplicates, with columns matched by name.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | The DataFrame to union with this one, matching columns by name. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A new DataFrame containing all rows from both DataFrames, including duplicates, with columns matched by name. |
Examples:
1 2 3 4 | |
╭───────┬───────┬───────┬────────╮
│ x ┆ y ┆ w ┆ z │
│ --- ┆ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 ┆ String │
╞═══════╪═══════╪═══════╪════════╡
│ 1 ┆ 4 ┆ 9 ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 10 ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ None ┆ 6 ┆ None ┆ a │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ None ┆ 6 ┆ None ┆ a │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ None ┆ 7 ┆ None ┆ b │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ None ┆ 7 ┆ None ┆ b │
╰───────┴───────┴───────┴────────╯
(Showing first 6 of 6 rows) Source code in daft/dataframe/dataframe.py
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union_by_name #
Returns the distinct union by name.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
other | DataFrame | The DataFrame to union with this one, matching columns by name. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A new DataFrame containing the distinct rows from both DataFrames, with columns matched by name. |
Examples:
1 2 3 4 | |
╭───────┬───────┬───────┬────────╮
│ x ┆ y ┆ w ┆ z │
│ --- ┆ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 ┆ String │
╞═══════╪═══════╪═══════╪════════╡
│ 1 ┆ 4 ┆ 9 ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 10 ┆ None │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ None ┆ 6 ┆ None ┆ a │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┤
│ None ┆ 7 ┆ None ┆ b │
╰───────┴───────┴───────┴────────╯
(Showing first 4 of 4 rows) Source code in daft/dataframe/dataframe.py
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unique #
unique(*by: ColumnInputType) -> DataFrame
Computes distinct rows, dropping duplicates.
Alias for DataFrame.distinct.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*by | Union[str, Expression] | columns to perform distinct on. Defaults to all columns. | () |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame that has only distinct rows. |
Examples:
1 2 3 4 5 | |
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 1 ┆ 4 ┆ 7 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 8 │
╰───────┴───────┴───────╯
(Showing first 2 of 2 rows) Source code in daft/dataframe/dataframe.py
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unpivot #
unpivot(ids: ManyColumnsInputType, values: ManyColumnsInputType = [], variable_name: str = 'variable', value_name: str = 'value') -> DataFrame
Unpivots a DataFrame from wide to long format.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
ids | ManyColumnsInputType | Columns to keep as identifiers | required |
values | Optional[ManyColumnsInputType] | Columns to unpivot. If not specified, all columns except ids will be unpivoted. | [] |
variable_name | Optional[str] | Name of the variable column. Defaults to "variable". | 'variable' |
value_name | Optional[str] | Name of the value column. Defaults to "value". | 'value' |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Unpivoted DataFrame |
Tip
See also melt
Examples:
1 2 3 4 5 6 7 8 9 10 11 | |
╭───────┬────────┬───────────╮
│ year ┆ month ┆ inventory │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ String ┆ Int64 │
╞═══════╪════════╪═══════════╡
│ 2020 ┆ Jan ┆ 10 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2020 ┆ Feb ┆ 20 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2021 ┆ Jan ┆ 30 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2021 ┆ Feb ┆ 40 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2022 ┆ Jan ┆ 50 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌╌╌╌╌┤
│ 2022 ┆ Feb ┆ 60 │
╰───────┴────────┴───────────╯
(Showing first 6 of 6 rows) Source code in daft/dataframe/dataframe.py
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var #
var(*cols: ColumnInputType, ddof: int = 1) -> DataFrame
Performs a global variance on the DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
*cols | Union[str, Expression] | columns to compute variance for | () |
ddof | int | Delta degrees of freedom used in the denominator | 1 |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Globally aggregated variance. Should be a single row. |
Examples:
1 2 3 4 | |
╭─────────╮
│ col_a │
│ --- │
│ Float64 │
╞═════════╡
│ 1 │
╰─────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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where #
where(predicate: Expression | str) -> DataFrame
Filters rows via a predicate expression, similar to SQL WHERE.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
predicate | Expression | expression that keeps row if evaluates to True. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | Filtered DataFrame. |
Examples:
1 2 3 | |
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 2 ┆ 6 ┆ 8 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 ┆ 9 │
╰───────┴───────┴───────╯
(Showing first 2 of 2 rows) You can also use a string expression as a predicate.
Note: this will use the method sql_expr to parse the string into an expression this may raise an error if the expression is not yet supported in the sql engine.
1 2 3 | |
╭───────┬───────┬───────╮
│ x ┆ y ┆ z │
│ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╡
│ 3 ┆ 6 ┆ 9 │
╰───────┴───────┴───────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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with_column #
with_column(column_name: str, expr: Expression) -> DataFrame
Adds a column to the current DataFrame with an Expression, equivalent to a select with all current columns and the new one.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
column_name | str | name of new column | required |
expr | Expression | expression of the new column. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with new column. |
Examples:
1 2 3 4 | |
╭───────┬───────╮
│ x ┆ x+1 │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 2 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 3 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 4 │
╰───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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with_column_renamed #
with_column_renamed(existing: str, new: str) -> DataFrame
Renames a column in the current DataFrame.
If the column in the DataFrame schema does not exist, this will be a no-op.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
existing | str | name of the existing column to rename | required |
new | str | new name for the column | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with the column renamed. |
Examples:
1 2 3 | |
╭───────┬───────╮
│ foo ┆ y │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
╰───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
3360 3361 3362 3363 3364 3365 3366 3367 3368 3369 3370 3371 3372 3373 3374 3375 3376 3377 3378 3379 3380 3381 3382 3383 3384 3385 3386 3387 3388 3389 3390 3391 3392 | |
with_columns #
with_columns(columns: dict[str, Expression]) -> DataFrame
Adds columns to the current DataFrame with Expressions, equivalent to a select with all current columns and the new ones.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
columns | Dict[str, Expression] | Dictionary of new columns in the format { name: expression } | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with new columns. |
Examples:
1 2 3 4 | |
╭───────┬───────┬───────┬───────╮
│ x ┆ y ┆ foo ┆ bar │
│ --- ┆ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 ┆ Int64 │
╞═══════╪═══════╪═══════╪═══════╡
│ 1 ┆ 4 ┆ 2 ┆ 3 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 ┆ 3 ┆ 3 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 ┆ 4 ┆ 3 │
╰───────┴───────┴───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
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with_columns_renamed #
with_columns_renamed(cols_map: dict[str, str]) -> DataFrame
Renames multiple columns in the current DataFrame.
If the columns in the DataFrame schema do not exist, this will be a no-op.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
cols_map | Dict[str, str] | Dictionary of columns to rename in the format { existing: new } | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | DataFrame with the columns renamed. |
Examples:
1 2 3 | |
╭───────┬───────╮
│ foo ┆ bar │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞═══════╪═══════╡
│ 1 ┆ 4 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 2 ┆ 5 │
├╌╌╌╌╌╌╌┼╌╌╌╌╌╌╌┤
│ 3 ┆ 6 │
╰───────┴───────╯
(Showing first 3 of 3 rows) Source code in daft/dataframe/dataframe.py
3394 3395 3396 3397 3398 3399 3400 3401 3402 3403 3404 3405 3406 3407 3408 3409 3410 3411 3412 3413 3414 3415 3416 3417 3418 3419 3420 3421 3422 3423 3424 3425 | |
write_bigtable #
write_bigtable(project_id: str, instance_id: str, table_id: str, row_key_column: str, column_family_mappings: dict[str, str], client_kwargs: dict[str, Any] | None = None, write_kwargs: dict[str, Any] | None = None, serialize_incompatible_types: bool = True) -> DataFrame
Write a DataFrame into a Google Cloud Bigtable table.
Bigtable only accepts datatypes that can be converted to bytes in cells (for more details, please consult the Bigtable documentation: https://cloud.google.com/bigtable/docs/overview#data-types). By default, write_bigtable automatically serializes incompatible types to JSON. This can be disabled by setting auto_convert=False.
This data sink transforms each row of the dataframe into Bigtable rows. A row key is always required. The row_key_column parameter can be used to specify the column name to use for the row key.
Every column must also belong to a column family. The column_family_mappings parameter can be used to specify the column family to use for each column. For example, if you have a column "name" and a column "age", you can specify a "user_data" column family by passing a dictionary like {"name": "user_data", "age": "user_data"}.
EXPERIMENTAL: This features is early in development and will change.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
project_id | str | The Google Cloud project ID. | required |
instance_id | str | The Bigtable instance ID. | required |
table_id | str | The table to write to. | required |
row_key_column | str | Column name for the row key. | required |
column_family_mappings | dict[str, str] | Mapping of column names to column families. | required |
client_kwargs | dict[str, Any] | None | Optional dictionary of arguments to pass to the Bigtable Client constructor. | None |
write_kwargs | dict[str, Any] | None | Optional dictionary of arguments to pass to the Bigtable MutationsBatcher. | None |
serialize_incompatible_types | bool | Whether to automatically convert non-bytes/int values to Bigtable-compatible formats. If False, will raise an error for unsupported types. Defaults to True. | True |
Source code in daft/dataframe/dataframe.py
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write_clickhouse #
write_clickhouse(table: str, *, host: str, port: int | None = None, user: str | None = None, password: str | None = None, database: str | None = None, client_kwargs: dict[str, Any] | None = None, write_kwargs: dict[str, Any] | None = None) -> DataFrame
Writes the DataFrame to a ClickHouse table.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
table | str | Name of the ClickHouse table to write to. | required |
host | str | ClickHouse host. | required |
port | int | None | ClickHouse port. | None |
user | str | None | ClickHouse user. | None |
password | str | None | ClickHouse password. | None |
database | str | None | ClickHouse database. | None |
client_kwargs | dict[str, Any] | None | Optional dictionary of arguments to pass to the ClickHouse client constructor. | None |
write_kwargs | dict[str, Any] | None | Optional dictionary of arguments to pass to the ClickHouse write() method. | None |
Examples:
1 2 3 | |
╭────────────────────┬─────────────────────╮
│ total_written_rows ┆ total_written_bytes │
│ --- ┆ --- │
│ Int64 ┆ Int64 │
╞════════════════════╪═════════════════════╡
│ 4 ┆ 32 │
╰────────────────────┴─────────────────────╯ Source code in daft/dataframe/dataframe.py
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write_csv #
write_csv(root_dir: str | Path, write_mode: Literal['append', 'overwrite', 'overwrite-partitions'] = 'append', partition_cols: list[ColumnInputType] | None = None, io_config: IOConfig | None = None, delimiter: str | None = None, quote: str | None = None, escape: str | None = None, header: bool | None = True, date_format: str | None = None, timestamp_format: str | None = None) -> DataFrame
Writes the DataFrame as CSV files, returning a new DataFrame with paths to the files that were written.
Files will be written to <root_dir>/* with randomly generated UUIDs as the file names.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
root_dir | str | root file path to write CSV files to. | required |
write_mode | str | Operation mode of the write. | 'append' |
partition_cols | Optional[List[ColumnInputType]] | How to subpartition each partition further. Defaults to None. | None |
io_config | Optional[IOConfig] | configurations to use when interacting with remote storage. | None |
delimiter | Optional[str] | Single-character field delimiter (default | None |
quote | Optional[str] | Single-character quote used around fields containing delimiters default | None |
escape | Optional[str] | Single-character escape for special characters default | None |
header | Optional[bool] | Whether to write a header row with column names, default True. | True |
date_format | Optional[str] | Format string for date columns. Uses chrono strftime format (e.g., "%Y-%m-%d", "%d/%m/%Y"). Defaults to None (ISO 8601 format). | None |
timestamp_format | Optional[str] | Format string for timestamp columns. Uses chrono strftime format (e.g., "%Y-%m-%d %H:%M:%S", "%+"). Defaults to None (ISO 8601 format). | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | The filenames that were written out as strings. |
Note
This call is blocking and will execute the DataFrame when called
Timezone handling: For timezone-aware timestamp columns, the timestamps are converted to the target timezone before formatting. For example, a timestamp stored as UTC but with timezone "America/New_York" will be formatted in Eastern Time, not UTC. If the timezone string is invalid, an error will be raised.
Examples:
Basic usage:
1 2 3 | |
Custom date format (e.g., DD/MM/YYYY):
1 2 3 | |
# Output: 15/01/2024 Custom timestamp format:
1 2 | |
# Output: 2024-01-15 10:30:45 ISO 8601 / RFC 3339 timestamp format:
1 | |
# Output: 2024-01-15T10:30:45+00:00 Tip
See also df.write_parquet() and df.write_json() other formats for writing DataFrames
Source code in daft/dataframe/dataframe.py
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write_deltalake #
write_deltalake(table: Union[str, Path, DeltaTable, UnityCatalogTable], partition_cols: list[str] | None = None, mode: Literal['append', 'overwrite', 'error', 'ignore'] = 'append', schema_mode: Literal['merge', 'overwrite'] | None = None, name: str | None = None, description: str | None = None, configuration: Mapping[str, str | None] | None = None, custom_metadata: dict[str, str] | None = None, dynamo_table_name: str | None = None, allow_unsafe_rename: bool = False, io_config: IOConfig | None = None, checkpoint: IdempotentCommit | None = None) -> DataFrame
Writes the DataFrame to a Delta Lake table, returning a new DataFrame with the operations that occurred.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
table | Union[str, Path, DeltaTable, UnityCatalogTable] | Destination Delta Lake Table or table URI to write dataframe to. | required |
partition_cols | List[str] | How to subpartition each partition further. If table exists, expected to match table's existing partitioning scheme, otherwise creates the table with specified partition columns. Defaults to None. | None |
mode | str | Operation mode of the write. | 'append' |
schema_mode | str | Schema mode of the write. If set to | None |
name | str | User-provided identifier for this table. | None |
description | str | User-provided description for this table. | None |
configuration | Mapping[str, Optional[str]] | A map containing configuration options for the metadata action. | None |
custom_metadata | Dict[str, str] | Custom metadata to add to the commit info. Keys with prefix | None |
dynamo_table_name | str | Name of the DynamoDB table to be used as the locking provider if writing to S3. | None |
allow_unsafe_rename | bool | Whether to allow unsafe rename when writing to S3 or local disk. Defaults to False. | False |
io_config | IOConfig | configurations to use when interacting with remote storage. | None |
checkpoint | IdempotentCommit | Bundled checkpoint store + idempotence key for an idempotent commit. When provided, the Delta commit's | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | The operations that occurred with this write. |
Note
This call is blocking and will execute the DataFrame when called.
When checkpoint is provided and write_deltalake raises after the Delta commit landed (e.g. a transient failure during the post-commit mark_committed bookkeeping), the user data is already durable in Delta. The next call with the same IdempotentCommit (same idempotence key) will detect the commit via its marker, finish the bookkeeping, and exit cleanly without producing a duplicate commit.
The returned DataFrame reflects only this call's writes — empty (0 rows) on a recovery short-circuit, populated when a new commit lands. Useful for run-to-run diffing.
Idempotence-key contract — read carefully:
- Same key + different inputs → silent no-op (data loss). The destination already has a commit tagged with the key, so nothing new is written.
- Different key + same retry → duplicate commit. The destination won't recognize the prior attempt and will commit again. Idempotence is broken.
The orchestrator pattern (run-id supplied from upstream DAG context) avoids both naturally.
Crashed runs leave orphan data files at the table location. Delta writes parquet files before the commit, so files from crashed attempts are not referenced by any commit but the bytes remain on disk.
Examples:
1 2 3 4 | |
Source code in daft/dataframe/dataframe.py
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write_huggingface #
write_huggingface(repo: str, split: str = 'train', data_dir: str = 'data', revision: str = 'main', overwrite: bool = False, commit_message: str = 'Upload dataset using Daft', commit_description: str | None = None, io_config: IOConfig | None = None) -> DataFrame
Write a DataFrame into a Hugging Face dataset.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
repo | str | The ID of the repository to push to in the following format: | required |
split | str | The name of the split that will be given to that dataset. | 'train' |
data_dir | str | Directory of the uploaded data files. | 'data' |
revision | str | Branch to push the uploaded files to. | 'main' |
overwrite | bool | Whether to overwrite or append. | False |
commit_message | str | Message to commit while pushing. | 'Upload dataset using Daft' |
commit_description | str | None | Description of the commit that will be created. | None |
io_config | IOConfig | None | Configurations to use when interacting with remote storage. | None |
Source code in daft/dataframe/dataframe.py
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write_iceberg #
write_iceberg(table: Table, mode: str = 'append', io_config: IOConfig | None = None, snapshot_properties: dict[str, str] | None = None, checkpoint: IdempotentCommit | None = None) -> DataFrame
Writes the DataFrame to an Iceberg table, returning a new DataFrame with the operations that occurred.
Can be run in either append or overwrite mode which will either appends the rows in the DataFrame or will delete the existing rows and then append the DataFrame rows respectively.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
table | Table | Destination PyIceberg Table to write dataframe to. | required |
mode | str | Operation mode of the write. | 'append' |
io_config | IOConfig | A custom IOConfig to use when accessing Iceberg object storage data. If provided, configurations set in | None |
snapshot_properties | dict[str, str] | Optional snapshot properties to set while writing to the table. Keys with prefix | None |
checkpoint | IdempotentCommit | Bundled checkpoint store + idempotence key for an idempotent commit. When provided, the snapshot summary is tagged with | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | The operations that occurred with this write. |
Note
This call is blocking and will execute the DataFrame when called.
When checkpoint is provided and write_iceberg raises after the catalog commit landed (e.g. a transient failure during the post-commit mark_committed bookkeeping), the user data is already durable in Iceberg. The next call with the same IdempotentCommit (same idempotence key) will detect the snapshot via its marker, finish the bookkeeping, and exit cleanly without producing a duplicate snapshot.
The returned DataFrame reflects only this call's writes — empty (0 rows) on a recovery short-circuit, populated when a new snapshot lands. Useful for run-to-run diffing.
Idempotence-key contract — read carefully:
- Same key + different inputs → silent no-op (data loss). The destination already has a snapshot tagged with the key, so nothing new is written.
- Different key + same retry → duplicate snapshot. The destination won't recognize the prior attempt and will commit again. Idempotence is broken.
The orchestrator pattern (run-id supplied from upstream DAG context) avoids both naturally.
Crashed runs leave orphan data files at the warehouse location. Iceberg writes stage data files before the snapshot commit, so files from crashed attempts are not referenced by any snapshot but the bytes remain on disk.
Examples:
1 2 3 4 5 6 | |
Source code in daft/dataframe/dataframe.py
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write_json #
write_json(root_dir: str | Path, write_mode: Literal['append', 'overwrite', 'overwrite-partitions'] = 'append', partition_cols: list[ColumnInputType] | None = None, io_config: IOConfig | None = None, ignore_null_fields: bool | None = False, date_format: str | None = None, timestamp_format: str | None = None) -> DataFrame
Writes the DataFrame as JSON files, returning a new DataFrame with paths to the files that were written.
Files will be written to <root_dir>/* with randomly generated UUIDs as the file names.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
root_dir | str | root file path to write JSON files to. | required |
write_mode | str | Operation mode of the write. | 'append' |
partition_cols | Optional[List[ColumnInputType]] | How to subpartition each partition further. Defaults to None. | None |
io_config | Optional[IOConfig] | configurations to use when interacting with remote storage. | None |
ignore_null_fields | Optional[bool] | Whether to ignore fields with null values when writing JSON. Defaults to False. | False |
date_format | Optional[str] | Format string for date columns. Uses chrono strftime format (e.g., "%Y-%m-%d", "%d/%m/%Y"). Defaults to None (ISO 8601 format). | None |
timestamp_format | Optional[str] | Format string for timestamp columns. Uses chrono strftime format (e.g., "%Y-%m-%d %H:%M:%S", "%+"). Defaults to None (ISO 8601 format). | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | The filenames that were written out as strings. |
Note
This call is blocking and will execute the DataFrame when called
Timezone handling: For timezone-aware timestamp columns, the timestamps are converted to the target timezone before formatting. For example, a timestamp stored as UTC but with timezone "America/New_York" will be formatted in Eastern Time, not UTC. If the timezone string is invalid, an error will be raised.
Examples:
Basic usage:
1 2 3 | |
Custom date format (e.g., DD/MM/YYYY):
1 2 3 | |
# Output: "15/01/2024" Custom timestamp format:
1 2 | |
# Output: "2024-01-15 10:30:45" ISO 8601 / RFC 3339 timestamp format:
1 | |
# Output: "2024-01-15T10:30:45+00:00" Source code in daft/dataframe/dataframe.py
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write_lance #
write_lance(uri: str | Path, mode: Literal['create', 'append', 'overwrite', 'merge'] = 'create', io_config: IOConfig | None = None, schema: Union[Schema, Schema] | None = None, left_on: str | None = None, right_on: str | None = None, **kwargs: Any) -> DataFrame
Writes the DataFrame to a Lance table.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
uri | str | Path | The URI of the Lance table to write to. Accepts a local path or an object-store URI like "s3://bucket/path". | required |
mode | Literal['create', 'append', 'overwrite', 'merge'] | The write mode. One of "create", "append", "overwrite", or "merge". | 'create' |
io_config | IOConfig | configurations to use when interacting with remote storage. | None |
schema | Schema | Schema | Desired schema to enforce during write. - If omitted, Daft will use the DataFrame's current schema. - If a pyarrow.Schema is provided, Daft will enforce the field order, types, and nullability by casting the data to the provided schema prior to write. Table-level (dataset) metadata present on the pyarrow schema is preserved during create/overwrite. - If the target Lance dataset already exists, the data will be cast to the existing table schema to ensure compatibility unless | None |
left_on/right_on | Optional[str] | Only supported in | required |
**kwargs | Any | Additional keyword arguments to pass to the Lance writer. | {} |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A DataFrame containing metadata about the written Lance table, such as number of fragments, number of deleted rows, number of small files, and version. |
Raises:
| Type | Description |
|---|---|
TypeError | If |
ValueError | When appending and the data schema cannot be cast to the existing table schema |
Examples:
1 2 3 4 5 6 7 | |
╭───────────────┬──────────────────┬─────────────────┬─────────╮
│ num_fragments ┆ num_deleted_rows ┆ num_small_files ┆ version │
│ --- ┆ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 ┆ Int64 │
╞═══════════════╪══════════════════╪═════════════════╪═════════╡
│ 1 ┆ 0 ┆ 1 ┆ 1 │
╰───────────────┴──────────────────┴─────────────────┴─────────╯
(Showing first 1 of 1 rows)
╭───────╮
│ a │
│ --- │
│ Int64 │
╞═══════╡
│ 1 │
├╌╌╌╌╌╌╌┤
│ 2 │
├╌╌╌╌╌╌╌┤
│ 3 │
├╌╌╌╌╌╌╌┤
│ 4 │
╰───────╯
(Showing first 4 of 4 rows)
╭───────────────┬──────────────────┬─────────────────┬─────────╮
│ num_fragments ┆ num_deleted_rows ┆ num_small_files ┆ version │
│ --- ┆ --- ┆ --- ┆ --- │
│ Int64 ┆ Int64 ┆ Int64 ┆ Int64 │
╞═══════════════╪══════════════════╪═════════════════╪═════════╡
│ 1 ┆ 0 ┆ 1 ┆ 2 │
╰───────────────┴──────────────────┴─────────────────┴─────────╯
(Showing first 1 of 1 rows) Source code in daft/dataframe/dataframe.py
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write_paimon #
write_paimon(table: Table, mode: str = 'append') -> DataFrame
Writes the DataFrame to an Apache Paimon table, returning a summary DataFrame.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
table | Table | Destination Paimon table obtained via | required |
mode | str | Write mode – | 'append' |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A summary DataFrame with columns |
DataFrame |
|
Note
This call is blocking and will execute the DataFrame when called.
Examples:
1 2 3 4 5 6 | |
Source code in daft/dataframe/dataframe.py
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write_parquet #
write_parquet(root_dir: str | Path, compression: str = 'snappy', write_mode: Literal['append', 'overwrite', 'overwrite-partitions'] = 'append', write_success_file: bool = False, partition_cols: list[ColumnInputType] | None = None, io_config: IOConfig | None = None, column_compression: dict[str, str] | None = None) -> DataFrame
Writes the DataFrame as parquet files, returning a new DataFrame with paths to the files that were written.
Files will be written to <root_dir>/* with randomly generated UUIDs as the file names.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
root_dir | str | root file path to write parquet files to. | required |
compression | str | default compression codec applied to every column. Defaults to "snappy". Accepts "snappy", "gzip", "zstd", "lz4", "lz4_raw", "brotli", "uncompressed", or "none" (case-insensitive). | 'snappy' |
write_mode | str | Operation mode of the write. | 'append' |
write_success_file | bool | Whether to write a | False |
partition_cols | Optional[List[ColumnInputType]] | How to subpartition each partition further. Defaults to None. | None |
io_config | Optional[IOConfig] | configurations to use when interacting with remote storage. | None |
column_compression | Optional[Dict[str, str]] | per-column compression overrides. Keys are dot-separated column paths (e.g. | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | The filenames that were written out as strings. |
Note
This call is blocking and will execute the DataFrame when called
Examples:
1 2 3 | |
Tip
See also df.write_csv() and df.write_json() Other formats for writing DataFrames
Source code in daft/dataframe/dataframe.py
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write_sink #
Writes the DataFrame to the given DataSink.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
sink | DataSink[WriteResultType] | The DataSink to write to. | required |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A dataframe from the micropartition returned by the DataSink's |
Note
This call is blocking and will execute the DataFrame when called
Source code in daft/dataframe/dataframe.py
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write_sql #
write_sql(table_name: str, conn: str | Callable[[], Connection], write_mode: Literal['append', 'overwrite', 'fail'] = 'append', column_types: dict[str, Any] | None = None, non_primitive_handling: Literal['bytes', 'str', 'error'] | None = None) -> DataFrame
Write the DataFrame to a SQL database and return write metrics.
The write is executed via :meth:daft.DataFrame.write_sink using an internal :class:daft.io._sql.SQLDataSink.
Primitive columns (ints, floats, bools, strings, binary, dates, timestamps) are written by converting to a pandas DataFrame and calling :meth:pandas.DataFrame.to_sql, letting SQLAlchemy or column_types choose concrete SQL types.
Non-primitive columns (lists, structs, maps, tensors, images, embeddings, python objects, etc.) are normalized according to non_primitive_handling (default None behaves like "str"): "str" serializes values to text (JSON for arrays/maps and other containers, str(..) otherwise), "bytes" writes UTF-8 bytes of that text, and "error" fails if such columns are present.
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
table_name | str | Name of the table to write to. | required |
conn | str | Callable[[], Connection] | Connection string or factory. | required |
write_mode | str | Mode to write to the table. "append", "overwrite", or "fail". Defaults to "append". | 'append' |
column_types | Optional[Dict[str, Any]] | Optional mapping from column names to SQLAlchemy types to use when creating the table or casting columns. Passed through to the underlying SQL engine when creating or writing the table. | None |
non_primitive_handling | Literal['bytes', 'str', 'error'] | None | Controls how non-primitive columns are normalized before reaching SQL; default | None |
Returns:
| Name | Type | Description |
|---|---|---|
DataFrame | DataFrame | A single-row DataFrame containing aggregate write metrics with columns |
Warning
This features is early in development and will likely experience API changes.
Note
Primitive columns still rely on pandas/SQLAlchemy (or column_types) for concrete SQL types, while non-primitive columns are pre-normalized in Python according to non_primitive_handling before reaching the SQL driver.
Examples:
Write to a SQL table using a database URL and explicit SQLAlchemy dtypes:
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Write to a SQL table using a SQLAlchemy connection factory and dtypes:
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Write to a SQL table using a database URL with column_types=None to rely on inferred types:
1 2 | |
Source code in daft/dataframe/dataframe.py
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write_turbopuffer #
write_turbopuffer(namespace: str | Expression, api_key: str | None = None, region: str | None = None, distance_metric: Literal['cosine_distance', 'euclidean_squared'] | None = None, schema: dict[str, Any] | None = None, id_column: str | None = None, vector_column: str | None = None, client_kwargs: dict[str, Any] | None = None, write_kwargs: dict[str, Any] | None = None) -> DataFrame
Writes the DataFrame to a Turbopuffer namespace.
This method transforms each row of the dataframe into a turbopuffer document. This means that an id column is always required. Optionally, the id_column parameter can be used to specify the column name to used for the id column. Note that the column with the name specified by id_column will be renamed to "id" when written to turbopuffer.
A vector column is required if the namespace has a vector index. Optionally, the vector_column parameter can be used to specify the column name to used for the vector index. Note that the column with the name specified by vector_column will be renamed to "vector" when written to turbopuffer.
All other columns become attributes.
The namespace parameter can be either a string (for a single namespace) or an expression (for multiple namespaces). When using an expression, the data will be partitioned by the computed namespace values and written to each namespace separately.
For more details on parameters, please see the turbopuffer documentation: https://turbopuffer.com/docs/write
Parameters:
| Name | Type | Description | Default |
|---|---|---|---|
namespace | str | Expression | The namespace to write to. Can be a string for a single namespace or an expression for multiple namespaces. | required |
api_key | str | None | Turbopuffer API key. | None |
region | str | None | Turbopuffer region. | None |
distance_metric | Literal['cosine_distance', 'euclidean_squared'] | None | Distance metric for vector similarity ("cosine_distance", "euclidean_squared"). | None |
schema | dict[str, Any] | None | Optional manual schema specification. | None |
id_column | str | None | Optional column name for the id column. The data sink will automatically rename the column to "id" for the id column. | None |
vector_column | str | None | Optional column name for the vector index column. The data sink will automatically rename the column to "vector" for the vector index. | None |
client_kwargs | dict[str, Any] | None | Optional dictionary of arguments to pass to the Turbopuffer client constructor. Explicit arguments (api_key, region) will be merged into client_kwargs. | None |
write_kwargs | dict[str, Any] | None | Optional dictionary of arguments to pass to the namespace.write() method. Explicit arguments (distance_metric, schema) will be merged into write_kwargs. | None |
Source code in daft/dataframe/dataframe.py
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