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from typing import Any, Dict, Iterable, List, Optional, Tuple, Union |
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from ray.data._internal.aggregate import Count, Max, Mean, Min, Std, Sum |
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from ray.data._internal.compute import ComputeStrategy |
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from ray.data._internal.logical.interfaces import LogicalPlan |
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from ray.data._internal.logical.operators.all_to_all_operator import Aggregate |
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from ray.data.aggregate import AggregateFn |
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from ray.data.block import BlockAccessor, CallableClass, UserDefinedFunction |
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from ray.data.dataset import DataBatch, Dataset |
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from ray.util.annotations import PublicAPI |
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CDS_API_GROUP = "Computations or Descriptive Stats" |
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FA_API_GROUP = "Function Application" |
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class _MultiColumnSortedKey: |
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"""Represents a tuple of group keys with a ``__lt__`` method |
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This is a simple implementation to support multi-column groupby. |
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While a 1D array of tuples suffices to maintain the lexicographical |
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sorted order, a comparison method is also needed in ``np.searchsorted`` |
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(for computing the group key boundaries). |
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""" |
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__slots__ = ("data",) |
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def __init__(self, *args): |
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self.data = tuple(args) |
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def __lt__(self, obj: "_MultiColumnSortedKey") -> bool: |
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return self.data < obj.data |
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def __repr__(self) -> str: |
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"""Print as T(1, 2)""" |
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return "T" + self.data.__repr__() |
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class GroupedData: |
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"""Represents a grouped dataset created by calling ``Dataset.groupby()``. |
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The actual groupby is deferred until an aggregation is applied. |
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""" |
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def __init__( |
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self, |
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dataset: Dataset, |
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key: Union[str, List[str]], |
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): |
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"""Construct a dataset grouped by key (internal API). |
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The constructor is not part of the GroupedData API. |
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Use the ``Dataset.groupby()`` method to construct one. |
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""" |
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self._dataset = dataset |
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self._key = key |
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def __repr__(self) -> str: |
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return ( |
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f"{self.__class__.__name__}(dataset={self._dataset}, " f"key={self._key!r})" |
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) |
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@PublicAPI(api_group=FA_API_GROUP) |
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def aggregate(self, *aggs: AggregateFn) -> Dataset: |
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"""Implements an accumulator-based aggregation. |
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Args: |
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aggs: Aggregations to do. |
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Returns: |
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The output is an dataset of ``n + 1`` columns where the first column |
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is the groupby key and the second through ``n + 1`` columns are the |
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results of the aggregations. |
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If groupby key is ``None`` then the key part of return is omitted. |
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""" |
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plan = self._dataset._plan.copy() |
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op = Aggregate( |
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self._dataset._logical_plan.dag, |
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key=self._key, |
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aggs=aggs, |
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) |
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logical_plan = LogicalPlan(op, self._dataset.context) |
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return Dataset( |
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plan, |
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logical_plan, |
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) |
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def _aggregate_on( |
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self, |
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agg_cls: type, |
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on: Union[str, List[str]], |
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ignore_nulls: bool, |
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*args, |
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**kwargs, |
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): |
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"""Helper for aggregating on a particular subset of the dataset. |
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This validates the `on` argument, and converts a list of column names |
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to a multi-aggregation. A null `on` results in a |
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multi-aggregation on all columns for an Arrow Dataset, and a single |
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aggregation on the entire row for a simple Dataset. |
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""" |
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aggs = self._dataset._build_multicolumn_aggs( |
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agg_cls, on, ignore_nulls, *args, skip_cols=self._key, **kwargs |
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) |
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return self.aggregate(*aggs) |
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@PublicAPI(api_group=FA_API_GROUP) |
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def map_groups( |
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self, |
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fn: UserDefinedFunction[DataBatch, DataBatch], |
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*, |
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compute: Union[str, ComputeStrategy] = None, |
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batch_format: Optional[str] = "default", |
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fn_args: Optional[Iterable[Any]] = None, |
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fn_kwargs: Optional[Dict[str, Any]] = None, |
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fn_constructor_args: Optional[Iterable[Any]] = None, |
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fn_constructor_kwargs: Optional[Dict[str, Any]] = None, |
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num_cpus: Optional[float] = None, |
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num_gpus: Optional[float] = None, |
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concurrency: Optional[Union[int, Tuple[int, int]]] = None, |
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**ray_remote_args, |
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) -> "Dataset": |
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"""Apply the given function to each group of records of this dataset. |
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While map_groups() is very flexible, note that it comes with downsides: |
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* It may be slower than using more specific methods such as min(), max(). |
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* It requires that each group fits in memory on a single node. |
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In general, prefer to use aggregate() instead of map_groups(). |
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.. warning:: |
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Specifying both ``num_cpus`` and ``num_gpus`` for map tasks is experimental, |
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and may result in scheduling or stability issues. Please |
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`report any issues <https://github.com/ray-project/ray/issues/new/choose>`_ |
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to the Ray team. |
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Examples: |
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>>> # Return a single record per group (list of multiple records in, |
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>>> # list of a single record out). |
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>>> import ray |
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>>> import pandas as pd |
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>>> import numpy as np |
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>>> # Get first value per group. |
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>>> ds = ray.data.from_items([ # doctest: +SKIP |
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... {"group": 1, "value": 1}, |
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... {"group": 1, "value": 2}, |
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... {"group": 2, "value": 3}, |
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... {"group": 2, "value": 4}]) |
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>>> ds.groupby("group").map_groups( # doctest: +SKIP |
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... lambda g: {"result": np.array([g["value"][0]])}) |
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>>> # Return multiple records per group (dataframe in, dataframe out). |
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>>> df = pd.DataFrame( |
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... {"A": ["a", "a", "b"], "B": [1, 1, 3], "C": [4, 6, 5]} |
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... ) |
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>>> ds = ray.data.from_pandas(df) # doctest: +SKIP |
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>>> grouped = ds.groupby("A") # doctest: +SKIP |
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>>> grouped.map_groups( # doctest: +SKIP |
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... lambda g: g.apply( |
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... lambda c: c / g[c.name].sum() if c.name in ["B", "C"] else c |
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... ) |
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... ) # doctest: +SKIP |
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Args: |
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fn: The function to apply to each group of records, or a class type |
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that can be instantiated to create such a callable. It takes as |
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input a batch of all records from a single group, and returns a |
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batch of zero or more records, similar to map_batches(). |
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compute: The compute strategy, either "tasks" (default) to use Ray |
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tasks, ``ray.data.ActorPoolStrategy(size=n)`` to use a fixed-size actor |
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pool, or ``ray.data.ActorPoolStrategy(min_size=m, max_size=n)`` for an |
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autoscaling actor pool. |
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batch_format: Specify ``"default"`` to use the default block format |
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(NumPy), ``"pandas"`` to select ``pandas.DataFrame``, "pyarrow" to |
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select ``pyarrow.Table``, or ``"numpy"`` to select |
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``Dict[str, numpy.ndarray]``, or None to return the underlying block |
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exactly as is with no additional formatting. |
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fn_args: Arguments to `fn`. |
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fn_kwargs: Keyword arguments to `fn`. |
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fn_constructor_args: Positional arguments to pass to ``fn``'s constructor. |
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You can only provide this if ``fn`` is a callable class. These arguments |
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are top-level arguments in the underlying Ray actor construction task. |
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fn_constructor_kwargs: Keyword arguments to pass to ``fn``'s constructor. |
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This can only be provided if ``fn`` is a callable class. These arguments |
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are top-level arguments in the underlying Ray actor construction task. |
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num_cpus: The number of CPUs to reserve for each parallel map worker. |
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num_gpus: The number of GPUs to reserve for each parallel map worker. For |
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example, specify `num_gpus=1` to request 1 GPU for each parallel map |
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worker. |
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ray_remote_args: Additional resource requirements to request from |
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ray (e.g., num_gpus=1 to request GPUs for the map tasks). |
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Returns: |
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The return type is determined by the return type of ``fn``, and the return |
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value is combined from results of all groups. |
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""" |
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if self._key is not None: |
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sorted_ds = self._dataset.sort(self._key) |
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else: |
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sorted_ds = self._dataset.repartition(1) |
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def get_key_boundaries(block_accessor: BlockAccessor) -> List[int]: |
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"""Compute block boundaries based on the key(s)""" |
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import numpy as np |
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keys = block_accessor.to_numpy(self._key) |
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if isinstance(keys, dict): |
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convert_to_multi_column_sorted_key = np.vectorize(_MultiColumnSortedKey) |
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keys: np.ndarray = convert_to_multi_column_sorted_key(*keys.values()) |
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boundaries = [] |
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start = 0 |
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while start < keys.size: |
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end = start + np.searchsorted(keys[start:], keys[start], side="right") |
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boundaries.append(end) |
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start = end |
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return boundaries |
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def apply_udf_to_groups(udf, batch, *args, **kwargs): |
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block = BlockAccessor.batch_to_block(batch) |
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block_accessor = BlockAccessor.for_block(block) |
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if self._key: |
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boundaries = get_key_boundaries(block_accessor) |
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else: |
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boundaries = [block_accessor.num_rows()] |
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start = 0 |
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for end in boundaries: |
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group_block = block_accessor.slice(start, end) |
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group_block_accessor = BlockAccessor.for_block(group_block) |
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group_batch = group_block_accessor.to_batch_format(batch_format) |
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applied = udf(group_batch, *args, **kwargs) |
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yield applied |
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start = end |
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if isinstance(fn, CallableClass): |
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class wrapped_fn: |
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def __init__(self, *args, **kwargs): |
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self.fn = fn(*args, **kwargs) |
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def __call__(self, batch, *args, **kwargs): |
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yield from apply_udf_to_groups(self.fn, batch, *args, **kwargs) |
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else: |
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def wrapped_fn(batch, *args, **kwargs): |
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yield from apply_udf_to_groups(fn, batch, *args, **kwargs) |
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wrapped_fn.__name__ = fn.__name__ |
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return sorted_ds._map_batches_without_batch_size_validation( |
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wrapped_fn, |
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batch_size=None, |
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compute=compute, |
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batch_format=batch_format, |
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zero_copy_batch=False, |
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fn_args=fn_args, |
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fn_kwargs=fn_kwargs, |
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fn_constructor_args=fn_constructor_args, |
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fn_constructor_kwargs=fn_constructor_kwargs, |
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num_cpus=num_cpus, |
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num_gpus=num_gpus, |
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concurrency=concurrency, |
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ray_remote_args_fn=None, |
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**ray_remote_args, |
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) |
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@PublicAPI(api_group=CDS_API_GROUP) |
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def count(self) -> Dataset: |
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"""Compute count aggregation. |
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Examples: |
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>>> import ray |
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>>> ray.data.from_items([ # doctest: +SKIP |
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... {"A": x % 3, "B": x} for x in range(100)]).groupby( # doctest: +SKIP |
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... "A").count() # doctest: +SKIP |
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Returns: |
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A dataset of ``[k, v]`` columns where ``k`` is the groupby key and |
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``v`` is the number of rows with that key. |
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If groupby key is ``None`` then the key part of return is omitted. |
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""" |
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return self.aggregate(Count()) |
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@PublicAPI(api_group=CDS_API_GROUP) |
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def sum( |
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self, on: Union[str, List[str]] = None, ignore_nulls: bool = True |
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) -> Dataset: |
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r"""Compute grouped sum aggregation. |
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Examples: |
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>>> import ray |
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>>> ray.data.from_items([ # doctest: +SKIP |
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... (i % 3, i, i**2) # doctest: +SKIP |
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... for i in range(100)]) \ # doctest: +SKIP |
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... .groupby(lambda x: x[0] % 3) \ # doctest: +SKIP |
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... .sum(lambda x: x[2]) # doctest: +SKIP |
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>>> ray.data.range(100).groupby("id").sum() # doctest: +SKIP |
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>>> ray.data.from_items([ # doctest: +SKIP |
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... {"A": i % 3, "B": i, "C": i**2} # doctest: +SKIP |
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... for i in range(100)]) \ # doctest: +SKIP |
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... .groupby("A") \ # doctest: +SKIP |
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... .sum(["B", "C"]) # doctest: +SKIP |
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Args: |
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on: a column name or a list of column names to aggregate. |
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ignore_nulls: Whether to ignore null values. If ``True``, null |
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values will be ignored when computing the sum; if ``False``, |
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if a null value is encountered, the output will be null. |
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We consider np.nan, None, and pd.NaT to be null values. |
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Default is ``True``. |
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Returns: |
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The sum result. |
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For different values of ``on``, the return varies: |
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- ``on=None``: a dataset containing a groupby key column, |
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``"k"``, and a column-wise sum column for each original column |
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in the dataset. |
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- ``on=["col_1", ..., "col_n"]``: a dataset of ``n + 1`` |
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columns where the first column is the groupby key and the second |
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through ``n + 1`` columns are the results of the aggregations. |
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If groupby key is ``None`` then the key part of return is omitted. |
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""" |
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return self._aggregate_on(Sum, on, ignore_nulls) |
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@PublicAPI(api_group=CDS_API_GROUP) |
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def min( |
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self, on: Union[str, List[str]] = None, ignore_nulls: bool = True |
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) -> Dataset: |
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"""Compute grouped min aggregation. |
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Examples: |
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>>> import ray |
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>>> ray.data.le(100).groupby("value").min() # doctest: +SKIP |
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>>> ray.data.from_items([ # doctest: +SKIP |
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... {"A": i % 3, "B": i, "C": i**2} # doctest: +SKIP |
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... for i in range(100)]) \ # doctest: +SKIP |
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... .groupby("A") \ # doctest: +SKIP |
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... .min(["B", "C"]) # doctest: +SKIP |
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Args: |
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on: a column name or a list of column names to aggregate. |
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ignore_nulls: Whether to ignore null values. If ``True``, null |
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values will be ignored when computing the min; if ``False``, |
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if a null value is encountered, the output will be null. |
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We consider np.nan, None, and pd.NaT to be null values. |
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Default is ``True``. |
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Returns: |
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The min result. |
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For different values of ``on``, the return varies: |
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- ``on=None``: a dataset containing a groupby key column, |
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``"k"``, and a column-wise min column for each original column in |
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the dataset. |
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- ``on=["col_1", ..., "col_n"]``: a dataset of ``n + 1`` |
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columns where the first column is the groupby key and the second |
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through ``n + 1`` columns are the results of the aggregations. |
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If groupby key is ``None`` then the key part of return is omitted. |
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""" |
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return self._aggregate_on(Min, on, ignore_nulls) |
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@PublicAPI(api_group=CDS_API_GROUP) |
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def max( |
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self, on: Union[str, List[str]] = None, ignore_nulls: bool = True |
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) -> Dataset: |
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"""Compute grouped max aggregation. |
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Examples: |
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>>> import ray |
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>>> ray.data.le(100).groupby("value").max() # doctest: +SKIP |
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>>> ray.data.from_items([ # doctest: +SKIP |
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... {"A": i % 3, "B": i, "C": i**2} # doctest: +SKIP |
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... for i in range(100)]) \ # doctest: +SKIP |
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... .groupby("A") \ # doctest: +SKIP |
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... .max(["B", "C"]) # doctest: +SKIP |
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Args: |
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on: a column name or a list of column names to aggregate. |
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ignore_nulls: Whether to ignore null values. If ``True``, null |
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values will be ignored when computing the max; if ``False``, |
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if a null value is encountered, the output will be null. |
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We consider np.nan, None, and pd.NaT to be null values. |
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Default is ``True``. |
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Returns: |
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The max result. |
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For different values of ``on``, the return varies: |
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- ``on=None``: a dataset containing a groupby key column, |
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``"k"``, and a column-wise max column for each original column in |
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the dataset. |
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- ``on=["col_1", ..., "col_n"]``: a dataset of ``n + 1`` |
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columns where the first column is the groupby key and the second |
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through ``n + 1`` columns are the results of the aggregations. |
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If groupby key is ``None`` then the key part of return is omitted. |
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""" |
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return self._aggregate_on(Max, on, ignore_nulls) |
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@PublicAPI(api_group=CDS_API_GROUP) |
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def mean( |
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self, on: Union[str, List[str]] = None, ignore_nulls: bool = True |
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) -> Dataset: |
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"""Compute grouped mean aggregation. |
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Examples: |
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>>> import ray |
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>>> ray.data.le(100).groupby("value").mean() # doctest: +SKIP |
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>>> ray.data.from_items([ # doctest: +SKIP |
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... {"A": i % 3, "B": i, "C": i**2} # doctest: +SKIP |
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... for i in range(100)]) \ # doctest: +SKIP |
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... .groupby("A") \ # doctest: +SKIP |
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... .mean(["B", "C"]) # doctest: +SKIP |
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Args: |
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on: a column name or a list of column names to aggregate. |
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ignore_nulls: Whether to ignore null values. If ``True``, null |
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values will be ignored when computing the mean; if ``False``, |
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if a null value is encountered, the output will be null. |
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|
We consider np.nan, None, and pd.NaT to be null values. |
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|
Default is ``True``. |
|
|
|
|
|
Returns: |
|
|
The mean result. |
|
|
|
|
|
For different values of ``on``, the return varies: |
|
|
|
|
|
- ``on=None``: a dataset containing a groupby key column, |
|
|
``"k"``, and a column-wise mean column for each original column |
|
|
in the dataset. |
|
|
- ``on=["col_1", ..., "col_n"]``: a dataset of ``n + 1`` |
|
|
columns where the first column is the groupby key and the second |
|
|
through ``n + 1`` columns are the results of the aggregations. |
|
|
|
|
|
If groupby key is ``None`` then the key part of return is omitted. |
|
|
""" |
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|
return self._aggregate_on(Mean, on, ignore_nulls) |
|
|
|
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|
@PublicAPI(api_group=CDS_API_GROUP) |
|
|
def std( |
|
|
self, |
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|
on: Union[str, List[str]] = None, |
|
|
ddof: int = 1, |
|
|
ignore_nulls: bool = True, |
|
|
) -> Dataset: |
|
|
"""Compute grouped standard deviation aggregation. |
|
|
|
|
|
Examples: |
|
|
>>> import ray |
|
|
>>> ray.data.range(100).groupby("id").std(ddof=0) # doctest: +SKIP |
|
|
>>> ray.data.from_items([ # doctest: +SKIP |
|
|
... {"A": i % 3, "B": i, "C": i**2} # doctest: +SKIP |
|
|
... for i in range(100)]) \ # doctest: +SKIP |
|
|
... .groupby("A") \ # doctest: +SKIP |
|
|
... .std(["B", "C"]) # doctest: +SKIP |
|
|
|
|
|
NOTE: This uses Welford's online method for an accumulator-style |
|
|
computation of the standard deviation. This method was chosen due to |
|
|
it's numerical stability, and it being computable in a single pass. |
|
|
This may give different (but more accurate) results than NumPy, Pandas, |
|
|
and sklearn, which use a less numerically stable two-pass algorithm. |
|
|
See |
|
|
https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Welford's_online_algorithm |
|
|
|
|
|
Args: |
|
|
on: a column name or a list of column names to aggregate. |
|
|
ddof: Delta Degrees of Freedom. The divisor used in calculations |
|
|
is ``N - ddof``, where ``N`` represents the number of elements. |
|
|
ignore_nulls: Whether to ignore null values. If ``True``, null |
|
|
values will be ignored when computing the std; if ``False``, |
|
|
if a null value is encountered, the output will be null. |
|
|
We consider np.nan, None, and pd.NaT to be null values. |
|
|
Default is ``True``. |
|
|
|
|
|
Returns: |
|
|
The standard deviation result. |
|
|
|
|
|
For different values of ``on``, the return varies: |
|
|
|
|
|
- ``on=None``: a dataset containing a groupby key column, |
|
|
``"k"``, and a column-wise std column for each original column in |
|
|
the dataset. |
|
|
- ``on=["col_1", ..., "col_n"]``: a dataset of ``n + 1`` |
|
|
columns where the first column is the groupby key and the second |
|
|
through ``n + 1`` columns are the results of the aggregations. |
|
|
|
|
|
If groupby key is ``None`` then the key part of return is omitted. |
|
|
""" |
|
|
return self._aggregate_on(Std, on, ignore_nulls, ddof=ddof) |
|
|
|
|
|
|
|
|
|
|
|
GroupedDataset = GroupedData |
|
|
|