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Dask Expressions

Dask Dataframes with query optimization.

This is a proof-of-concept rewrite of Dask dataframe that includes query optimization and generally improved organization.

Example

import dask_expr as dx

df = dx.datasets.timeseries()
df.head()

df.groupby("name").x.mean().compute()

Query Representation

Dask-expr encodes user code in an expression tree:

>>> df.x.mean().pprint()

Mean:
  Projection: columns='x'
    Timeseries: seed=1896674884

This expression tree will be optimized and modified before execution:

>>> df.x.mean().optimize().pprint()

Div:
  Sum:
    Fused(375f9):
    | Projection: columns='x'
    |   Timeseries: dtypes={'x': <class 'float'>} seed=1896674884
  Count:
    Fused(375f9):
    | Projection: columns='x'
    |   Timeseries: dtypes={'x': <class 'float'>} seed=1896674884

Stability

This project is a work in progress and will be changed without notice or deprecation warning. Please provide feedback, but it's best to avoid use in production settings.

API Coverage

dask_expr.DataFrame

  • abs
  • add_prefix
  • add_sufix
  • align
  • all
  • any
  • apply
  • assign
  • astype
  • clip
  • combine_first
  • copy
  • count
  • dask
  • drop
  • drop_duplicates
  • dropna
  • eval
  • explode
  • fillna
  • groupby
  • head
  • idxmax
  • idxmin
  • index
  • isin
  • isna
  • join
  • map
  • map_partitions
  • max
  • memory_usage
  • merge
  • min
  • min
  • mode
  • nlargest
  • nsmallest
  • nunique_approx
  • partitions
  • pivot_table
  • prod
  • rename
  • rename_axis
  • repartition
  • replace
  • reset_index
  • round
  • sample
  • sort_values
  • select_dtypes
  • set_index
  • shuffle
  • std
  • sum
  • tail
  • to_parquet
  • to_timestamp
  • var
  • visualize

dask_expr.Series

  • abs
  • align
  • all
  • any
  • apply
  • astype
  • between
  • clip
  • combine_first
  • copy
  • count
  • dask
  • drop_duplicates
  • dropna
  • explode
  • fillna
  • groupby
  • head
  • idxmax
  • idxmin
  • index
  • isin
  • isna
  • map
  • map_partitions
  • max
  • memory_usage
  • min
  • min
  • mode
  • nlargest
  • nsmallest
  • nunique_approx
  • partitions
  • prod
  • rename_axis
  • repartition
  • replace
  • reset_index
  • round
  • shuffle
  • std
  • sum
  • tail
  • to_frame
  • to_timestamp
  • unique
  • value_counts
  • var
  • visualize

dask_expr.Index

  • abs
  • align
  • all
  • any
  • apply
  • astype
  • clip
  • combine_first
  • copy
  • count
  • dask
  • fillna
  • groupby
  • head
  • idxmax
  • idxmin
  • index
  • isin
  • isna
  • map_partitions
  • max
  • memory_usage
  • min
  • min
  • mode
  • nunique_approx
  • partitions
  • prod
  • rename_axis
  • repartition
  • replace
  • reset_index
  • round
  • shuffle
  • std
  • sum
  • tail
  • to_frame
  • to_timestamp
  • var
  • visualize

dask_expr._groupby.GroupBy

  • agg
  • aggregate
  • count
  • first
  • last
  • max
  • mean
  • min
  • prod
  • size
  • std
  • sum
  • value_counts
  • var

Binary operators (DataFrame, Series, and Index):

  • __add__
  • __radd__
  • __sub__
  • __rsub__
  • __mul__
  • __rmul__
  • __truediv__
  • __rtruediv__
  • __lt__
  • __rlt__
  • __gt__
  • __rgt__
  • __le__
  • __rle__
  • __ge__
  • __rge__
  • __eq__
  • __ne__
  • __and__
  • __rand__
  • __or__
  • __ror__
  • __xor__
  • __rxor__

Unary operators (DataFrame, Series, and Index):

  • __invert__
  • __neg__
  • __pos__

Accessors:

  • CategoricalAccessor
  • DatetimeAccessor
  • StringAccessor