430 lines
12 KiB
Python
430 lines
12 KiB
Python
"""
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Module responsible for execution of NDFrame.describe() method.
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Method NDFrame.describe() delegates actual execution to function describe_ndframe().
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"""
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from __future__ import annotations
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from abc import (
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ABC,
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abstractmethod,
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)
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from typing import (
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TYPE_CHECKING,
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Any,
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Callable,
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Hashable,
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Sequence,
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cast,
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)
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import warnings
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import numpy as np
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from pandas._libs.tslibs import Timestamp
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from pandas._typing import (
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DtypeObj,
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NDFrameT,
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npt,
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)
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from pandas.util._exceptions import find_stack_level
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from pandas.util._validators import validate_percentile
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from pandas.core.dtypes.common import (
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is_bool_dtype,
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is_complex_dtype,
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is_datetime64_any_dtype,
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is_extension_array_dtype,
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is_numeric_dtype,
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is_timedelta64_dtype,
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)
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import pandas as pd
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from pandas.core.reshape.concat import concat
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from pandas.io.formats.format import format_percentiles
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if TYPE_CHECKING:
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from pandas import (
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DataFrame,
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Series,
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)
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def describe_ndframe(
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*,
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obj: NDFrameT,
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include: str | Sequence[str] | None,
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exclude: str | Sequence[str] | None,
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datetime_is_numeric: bool,
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percentiles: Sequence[float] | np.ndarray | None,
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) -> NDFrameT:
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"""Describe series or dataframe.
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Called from pandas.core.generic.NDFrame.describe()
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Parameters
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----------
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obj: DataFrame or Series
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Either dataframe or series to be described.
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include : 'all', list-like of dtypes or None (default), optional
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A white list of data types to include in the result. Ignored for ``Series``.
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exclude : list-like of dtypes or None (default), optional,
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A black list of data types to omit from the result. Ignored for ``Series``.
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datetime_is_numeric : bool, default False
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Whether to treat datetime dtypes as numeric.
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percentiles : list-like of numbers, optional
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The percentiles to include in the output. All should fall between 0 and 1.
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The default is ``[.25, .5, .75]``, which returns the 25th, 50th, and
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75th percentiles.
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Returns
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-------
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Dataframe or series description.
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"""
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percentiles = refine_percentiles(percentiles)
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describer: NDFrameDescriberAbstract
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if obj.ndim == 1:
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describer = SeriesDescriber(
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obj=cast("Series", obj),
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datetime_is_numeric=datetime_is_numeric,
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)
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else:
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describer = DataFrameDescriber(
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obj=cast("DataFrame", obj),
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include=include,
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exclude=exclude,
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datetime_is_numeric=datetime_is_numeric,
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)
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result = describer.describe(percentiles=percentiles)
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return cast(NDFrameT, result)
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class NDFrameDescriberAbstract(ABC):
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"""Abstract class for describing dataframe or series.
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Parameters
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----------
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obj : Series or DataFrame
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Object to be described.
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datetime_is_numeric : bool
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Whether to treat datetime dtypes as numeric.
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"""
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def __init__(self, obj: DataFrame | Series, datetime_is_numeric: bool) -> None:
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self.obj = obj
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self.datetime_is_numeric = datetime_is_numeric
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@abstractmethod
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def describe(self, percentiles: Sequence[float] | np.ndarray) -> DataFrame | Series:
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"""Do describe either series or dataframe.
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Parameters
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----------
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percentiles : list-like of numbers
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The percentiles to include in the output.
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"""
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class SeriesDescriber(NDFrameDescriberAbstract):
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"""Class responsible for creating series description."""
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obj: Series
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def describe(self, percentiles: Sequence[float] | np.ndarray) -> Series:
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describe_func = select_describe_func(
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self.obj,
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self.datetime_is_numeric,
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)
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return describe_func(self.obj, percentiles)
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class DataFrameDescriber(NDFrameDescriberAbstract):
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"""Class responsible for creating dataobj description.
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Parameters
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----------
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obj : DataFrame
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DataFrame to be described.
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include : 'all', list-like of dtypes or None
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A white list of data types to include in the result.
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exclude : list-like of dtypes or None
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A black list of data types to omit from the result.
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datetime_is_numeric : bool
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Whether to treat datetime dtypes as numeric.
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"""
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def __init__(
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self,
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obj: DataFrame,
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*,
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include: str | Sequence[str] | None,
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exclude: str | Sequence[str] | None,
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datetime_is_numeric: bool,
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) -> None:
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self.include = include
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self.exclude = exclude
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if obj.ndim == 2 and obj.columns.size == 0:
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raise ValueError("Cannot describe a DataFrame without columns")
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super().__init__(obj, datetime_is_numeric=datetime_is_numeric)
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def describe(self, percentiles: Sequence[float] | np.ndarray) -> DataFrame:
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data = self._select_data()
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ldesc: list[Series] = []
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for _, series in data.items():
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describe_func = select_describe_func(series, self.datetime_is_numeric)
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ldesc.append(describe_func(series, percentiles))
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col_names = reorder_columns(ldesc)
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d = concat(
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[x.reindex(col_names, copy=False) for x in ldesc],
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axis=1,
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sort=False,
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)
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d.columns = data.columns.copy()
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return d
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def _select_data(self):
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"""Select columns to be described."""
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if (self.include is None) and (self.exclude is None):
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# when some numerics are found, keep only numerics
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default_include: list[npt.DTypeLike] = [np.number]
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if self.datetime_is_numeric:
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default_include.append("datetime")
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data = self.obj.select_dtypes(include=default_include)
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if len(data.columns) == 0:
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data = self.obj
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elif self.include == "all":
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if self.exclude is not None:
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msg = "exclude must be None when include is 'all'"
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raise ValueError(msg)
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data = self.obj
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else:
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data = self.obj.select_dtypes(
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include=self.include,
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exclude=self.exclude,
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)
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return data
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def reorder_columns(ldesc: Sequence[Series]) -> list[Hashable]:
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"""Set a convenient order for rows for display."""
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names: list[Hashable] = []
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ldesc_indexes = sorted((x.index for x in ldesc), key=len)
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for idxnames in ldesc_indexes:
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for name in idxnames:
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if name not in names:
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names.append(name)
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return names
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def describe_numeric_1d(series: Series, percentiles: Sequence[float]) -> Series:
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"""Describe series containing numerical data.
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Parameters
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----------
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series : Series
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Series to be described.
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percentiles : list-like of numbers
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The percentiles to include in the output.
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"""
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from pandas import Series
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formatted_percentiles = format_percentiles(percentiles)
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stat_index = ["count", "mean", "std", "min"] + formatted_percentiles + ["max"]
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d = (
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[series.count(), series.mean(), series.std(), series.min()]
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+ series.quantile(percentiles).tolist()
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+ [series.max()]
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)
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# GH#48340 - always return float on non-complex numeric data
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dtype: DtypeObj | None
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if is_extension_array_dtype(series):
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dtype = pd.Float64Dtype()
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elif is_numeric_dtype(series) and not is_complex_dtype(series):
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dtype = np.dtype("float")
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else:
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dtype = None
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return Series(d, index=stat_index, name=series.name, dtype=dtype)
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def describe_categorical_1d(
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data: Series,
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percentiles_ignored: Sequence[float],
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) -> Series:
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"""Describe series containing categorical data.
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Parameters
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----------
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data : Series
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Series to be described.
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percentiles_ignored : list-like of numbers
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Ignored, but in place to unify interface.
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"""
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names = ["count", "unique", "top", "freq"]
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objcounts = data.value_counts()
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count_unique = len(objcounts[objcounts != 0])
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if count_unique > 0:
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top, freq = objcounts.index[0], objcounts.iloc[0]
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dtype = None
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else:
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# If the DataFrame is empty, set 'top' and 'freq' to None
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# to maintain output shape consistency
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top, freq = np.nan, np.nan
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dtype = "object"
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result = [data.count(), count_unique, top, freq]
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from pandas import Series
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return Series(result, index=names, name=data.name, dtype=dtype)
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def describe_timestamp_as_categorical_1d(
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data: Series,
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percentiles_ignored: Sequence[float],
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) -> Series:
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"""Describe series containing timestamp data treated as categorical.
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Parameters
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----------
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data : Series
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Series to be described.
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percentiles_ignored : list-like of numbers
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Ignored, but in place to unify interface.
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"""
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names = ["count", "unique"]
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objcounts = data.value_counts()
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count_unique = len(objcounts[objcounts != 0])
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result = [data.count(), count_unique]
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dtype = None
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if count_unique > 0:
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top, freq = objcounts.index[0], objcounts.iloc[0]
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tz = data.dt.tz
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asint = data.dropna().values.view("i8")
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top = Timestamp(top)
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if top.tzinfo is not None and tz is not None:
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# Don't tz_localize(None) if key is already tz-aware
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top = top.tz_convert(tz)
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else:
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top = top.tz_localize(tz)
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names += ["top", "freq", "first", "last"]
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result += [
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top,
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freq,
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Timestamp(asint.min(), tz=tz),
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Timestamp(asint.max(), tz=tz),
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]
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# If the DataFrame is empty, set 'top' and 'freq' to None
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# to maintain output shape consistency
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else:
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names += ["top", "freq"]
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result += [np.nan, np.nan]
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dtype = "object"
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from pandas import Series
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return Series(result, index=names, name=data.name, dtype=dtype)
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def describe_timestamp_1d(data: Series, percentiles: Sequence[float]) -> Series:
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"""Describe series containing datetime64 dtype.
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Parameters
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----------
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data : Series
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Series to be described.
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percentiles : list-like of numbers
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The percentiles to include in the output.
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"""
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# GH-30164
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from pandas import Series
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formatted_percentiles = format_percentiles(percentiles)
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stat_index = ["count", "mean", "min"] + formatted_percentiles + ["max"]
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d = (
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[data.count(), data.mean(), data.min()]
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+ data.quantile(percentiles).tolist()
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+ [data.max()]
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)
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return Series(d, index=stat_index, name=data.name)
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def select_describe_func(
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data: Series,
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datetime_is_numeric: bool,
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) -> Callable:
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"""Select proper function for describing series based on data type.
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Parameters
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----------
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data : Series
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Series to be described.
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datetime_is_numeric : bool
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Whether to treat datetime dtypes as numeric.
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"""
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if is_bool_dtype(data.dtype):
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return describe_categorical_1d
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elif is_numeric_dtype(data):
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return describe_numeric_1d
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elif is_datetime64_any_dtype(data.dtype):
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if datetime_is_numeric:
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return describe_timestamp_1d
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else:
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warnings.warn(
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"Treating datetime data as categorical rather than numeric in "
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"`.describe` is deprecated and will be removed in a future "
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"version of pandas. Specify `datetime_is_numeric=True` to "
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"silence this warning and adopt the future behavior now.",
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FutureWarning,
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stacklevel=find_stack_level(),
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)
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return describe_timestamp_as_categorical_1d
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elif is_timedelta64_dtype(data.dtype):
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return describe_numeric_1d
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else:
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return describe_categorical_1d
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def refine_percentiles(
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percentiles: Sequence[float] | np.ndarray | None,
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) -> np.ndarray[Any, np.dtype[np.float64]]:
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"""
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Ensure that percentiles are unique and sorted.
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Parameters
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----------
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percentiles : list-like of numbers, optional
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The percentiles to include in the output.
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"""
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if percentiles is None:
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return np.array([0.25, 0.5, 0.75])
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# explicit conversion of `percentiles` to list
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percentiles = list(percentiles)
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# get them all to be in [0, 1]
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validate_percentile(percentiles)
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# median should always be included
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if 0.5 not in percentiles:
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percentiles.append(0.5)
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percentiles = np.asarray(percentiles)
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# sort and check for duplicates
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unique_pcts = np.unique(percentiles)
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assert percentiles is not None
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if len(unique_pcts) < len(percentiles):
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raise ValueError("percentiles cannot contain duplicates")
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return unique_pcts
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