diff --git "a/venv/lib/python3.10/site-packages/pandas/core/arrays/categorical.py" "b/venv/lib/python3.10/site-packages/pandas/core/arrays/categorical.py" new file mode 100644--- /dev/null +++ "b/venv/lib/python3.10/site-packages/pandas/core/arrays/categorical.py" @@ -0,0 +1,3070 @@ +from __future__ import annotations + +from csv import QUOTE_NONNUMERIC +from functools import partial +import operator +from shutil import get_terminal_size +from typing import ( + TYPE_CHECKING, + Literal, + cast, + overload, +) +import warnings + +import numpy as np + +from pandas._config import get_option + +from pandas._libs import ( + NaT, + algos as libalgos, + lib, +) +from pandas._libs.arrays import NDArrayBacked +from pandas.compat.numpy import function as nv +from pandas.util._exceptions import find_stack_level +from pandas.util._validators import validate_bool_kwarg + +from pandas.core.dtypes.cast import ( + coerce_indexer_dtype, + find_common_type, +) +from pandas.core.dtypes.common import ( + ensure_int64, + ensure_platform_int, + is_any_real_numeric_dtype, + is_bool_dtype, + is_dict_like, + is_hashable, + is_integer_dtype, + is_list_like, + is_scalar, + needs_i8_conversion, + pandas_dtype, +) +from pandas.core.dtypes.dtypes import ( + ArrowDtype, + CategoricalDtype, + CategoricalDtypeType, + ExtensionDtype, +) +from pandas.core.dtypes.generic import ( + ABCIndex, + ABCSeries, +) +from pandas.core.dtypes.missing import ( + is_valid_na_for_dtype, + isna, +) + +from pandas.core import ( + algorithms, + arraylike, + ops, +) +from pandas.core.accessor import ( + PandasDelegate, + delegate_names, +) +from pandas.core.algorithms import ( + factorize, + take_nd, +) +from pandas.core.arrays._mixins import ( + NDArrayBackedExtensionArray, + ravel_compat, +) +from pandas.core.base import ( + ExtensionArray, + NoNewAttributesMixin, + PandasObject, +) +import pandas.core.common as com +from pandas.core.construction import ( + extract_array, + sanitize_array, +) +from pandas.core.ops.common import unpack_zerodim_and_defer +from pandas.core.sorting import nargsort +from pandas.core.strings.object_array import ObjectStringArrayMixin + +from pandas.io.formats import console + +if TYPE_CHECKING: + from collections.abc import ( + Hashable, + Iterator, + Sequence, + ) + + from pandas._typing import ( + ArrayLike, + AstypeArg, + AxisInt, + Dtype, + DtypeObj, + NpDtype, + Ordered, + Self, + Shape, + SortKind, + npt, + ) + + from pandas import ( + DataFrame, + Index, + Series, + ) + + +def _cat_compare_op(op): + opname = f"__{op.__name__}__" + fill_value = op is operator.ne + + @unpack_zerodim_and_defer(opname) + def func(self, other): + hashable = is_hashable(other) + if is_list_like(other) and len(other) != len(self) and not hashable: + # in hashable case we may have a tuple that is itself a category + raise ValueError("Lengths must match.") + + if not self.ordered: + if opname in ["__lt__", "__gt__", "__le__", "__ge__"]: + raise TypeError( + "Unordered Categoricals can only compare equality or not" + ) + if isinstance(other, Categorical): + # Two Categoricals can only be compared if the categories are + # the same (maybe up to ordering, depending on ordered) + + msg = "Categoricals can only be compared if 'categories' are the same." + if not self._categories_match_up_to_permutation(other): + raise TypeError(msg) + + if not self.ordered and not self.categories.equals(other.categories): + # both unordered and different order + other_codes = recode_for_categories( + other.codes, other.categories, self.categories, copy=False + ) + else: + other_codes = other._codes + + ret = op(self._codes, other_codes) + mask = (self._codes == -1) | (other_codes == -1) + if mask.any(): + ret[mask] = fill_value + return ret + + if hashable: + if other in self.categories: + i = self._unbox_scalar(other) + ret = op(self._codes, i) + + if opname not in {"__eq__", "__ge__", "__gt__"}: + # GH#29820 performance trick; get_loc will always give i>=0, + # so in the cases (__ne__, __le__, __lt__) the setting + # here is a no-op, so can be skipped. + mask = self._codes == -1 + ret[mask] = fill_value + return ret + else: + return ops.invalid_comparison(self, other, op) + else: + # allow categorical vs object dtype array comparisons for equality + # these are only positional comparisons + if opname not in ["__eq__", "__ne__"]: + raise TypeError( + f"Cannot compare a Categorical for op {opname} with " + f"type {type(other)}.\nIf you want to compare values, " + "use 'np.asarray(cat) other'." + ) + + if isinstance(other, ExtensionArray) and needs_i8_conversion(other.dtype): + # We would return NotImplemented here, but that messes up + # ExtensionIndex's wrapped methods + return op(other, self) + return getattr(np.array(self), opname)(np.array(other)) + + func.__name__ = opname + + return func + + +def contains(cat, key, container) -> bool: + """ + Helper for membership check for ``key`` in ``cat``. + + This is a helper method for :method:`__contains__` + and :class:`CategoricalIndex.__contains__`. + + Returns True if ``key`` is in ``cat.categories`` and the + location of ``key`` in ``categories`` is in ``container``. + + Parameters + ---------- + cat : :class:`Categorical`or :class:`categoricalIndex` + key : a hashable object + The key to check membership for. + container : Container (e.g. list-like or mapping) + The container to check for membership in. + + Returns + ------- + is_in : bool + True if ``key`` is in ``self.categories`` and location of + ``key`` in ``categories`` is in ``container``, else False. + + Notes + ----- + This method does not check for NaN values. Do that separately + before calling this method. + """ + hash(key) + + # get location of key in categories. + # If a KeyError, the key isn't in categories, so logically + # can't be in container either. + try: + loc = cat.categories.get_loc(key) + except (KeyError, TypeError): + return False + + # loc is the location of key in categories, but also the *value* + # for key in container. So, `key` may be in categories, + # but still not in `container`. Example ('b' in categories, + # but not in values): + # 'b' in Categorical(['a'], categories=['a', 'b']) # False + if is_scalar(loc): + return loc in container + else: + # if categories is an IntervalIndex, loc is an array. + return any(loc_ in container for loc_ in loc) + + +class Categorical(NDArrayBackedExtensionArray, PandasObject, ObjectStringArrayMixin): + """ + Represent a categorical variable in classic R / S-plus fashion. + + `Categoricals` can only take on a limited, and usually fixed, number + of possible values (`categories`). In contrast to statistical categorical + variables, a `Categorical` might have an order, but numerical operations + (additions, divisions, ...) are not possible. + + All values of the `Categorical` are either in `categories` or `np.nan`. + Assigning values outside of `categories` will raise a `ValueError`. Order + is defined by the order of the `categories`, not lexical order of the + values. + + Parameters + ---------- + values : list-like + The values of the categorical. If categories are given, values not in + categories will be replaced with NaN. + categories : Index-like (unique), optional + The unique categories for this categorical. If not given, the + categories are assumed to be the unique values of `values` (sorted, if + possible, otherwise in the order in which they appear). + ordered : bool, default False + Whether or not this categorical is treated as a ordered categorical. + If True, the resulting categorical will be ordered. + An ordered categorical respects, when sorted, the order of its + `categories` attribute (which in turn is the `categories` argument, if + provided). + dtype : CategoricalDtype + An instance of ``CategoricalDtype`` to use for this categorical. + + Attributes + ---------- + categories : Index + The categories of this categorical. + codes : ndarray + The codes (integer positions, which point to the categories) of this + categorical, read only. + ordered : bool + Whether or not this Categorical is ordered. + dtype : CategoricalDtype + The instance of ``CategoricalDtype`` storing the ``categories`` + and ``ordered``. + + Methods + ------- + from_codes + __array__ + + Raises + ------ + ValueError + If the categories do not validate. + TypeError + If an explicit ``ordered=True`` is given but no `categories` and the + `values` are not sortable. + + See Also + -------- + CategoricalDtype : Type for categorical data. + CategoricalIndex : An Index with an underlying ``Categorical``. + + Notes + ----- + See the `user guide + `__ + for more. + + Examples + -------- + >>> pd.Categorical([1, 2, 3, 1, 2, 3]) + [1, 2, 3, 1, 2, 3] + Categories (3, int64): [1, 2, 3] + + >>> pd.Categorical(['a', 'b', 'c', 'a', 'b', 'c']) + ['a', 'b', 'c', 'a', 'b', 'c'] + Categories (3, object): ['a', 'b', 'c'] + + Missing values are not included as a category. + + >>> c = pd.Categorical([1, 2, 3, 1, 2, 3, np.nan]) + >>> c + [1, 2, 3, 1, 2, 3, NaN] + Categories (3, int64): [1, 2, 3] + + However, their presence is indicated in the `codes` attribute + by code `-1`. + + >>> c.codes + array([ 0, 1, 2, 0, 1, 2, -1], dtype=int8) + + Ordered `Categoricals` can be sorted according to the custom order + of the categories and can have a min and max value. + + >>> c = pd.Categorical(['a', 'b', 'c', 'a', 'b', 'c'], ordered=True, + ... categories=['c', 'b', 'a']) + >>> c + ['a', 'b', 'c', 'a', 'b', 'c'] + Categories (3, object): ['c' < 'b' < 'a'] + >>> c.min() + 'c' + """ + + # For comparisons, so that numpy uses our implementation if the compare + # ops, which raise + __array_priority__ = 1000 + # tolist is not actually deprecated, just suppressed in the __dir__ + _hidden_attrs = PandasObject._hidden_attrs | frozenset(["tolist"]) + _typ = "categorical" + + _dtype: CategoricalDtype + + @classmethod + # error: Argument 2 of "_simple_new" is incompatible with supertype + # "NDArrayBacked"; supertype defines the argument type as + # "Union[dtype[Any], ExtensionDtype]" + def _simple_new( # type: ignore[override] + cls, codes: np.ndarray, dtype: CategoricalDtype + ) -> Self: + # NB: This is not _quite_ as simple as the "usual" _simple_new + codes = coerce_indexer_dtype(codes, dtype.categories) + dtype = CategoricalDtype(ordered=False).update_dtype(dtype) + return super()._simple_new(codes, dtype) + + def __init__( + self, + values, + categories=None, + ordered=None, + dtype: Dtype | None = None, + fastpath: bool | lib.NoDefault = lib.no_default, + copy: bool = True, + ) -> None: + if fastpath is not lib.no_default: + # GH#20110 + warnings.warn( + "The 'fastpath' keyword in Categorical is deprecated and will " + "be removed in a future version. Use Categorical.from_codes instead", + DeprecationWarning, + stacklevel=find_stack_level(), + ) + else: + fastpath = False + + dtype = CategoricalDtype._from_values_or_dtype( + values, categories, ordered, dtype + ) + # At this point, dtype is always a CategoricalDtype, but + # we may have dtype.categories be None, and we need to + # infer categories in a factorization step further below + + if fastpath: + codes = coerce_indexer_dtype(values, dtype.categories) + dtype = CategoricalDtype(ordered=False).update_dtype(dtype) + super().__init__(codes, dtype) + return + + if not is_list_like(values): + # GH#38433 + raise TypeError("Categorical input must be list-like") + + # null_mask indicates missing values we want to exclude from inference. + # This means: only missing values in list-likes (not arrays/ndframes). + null_mask = np.array(False) + + # sanitize input + vdtype = getattr(values, "dtype", None) + if isinstance(vdtype, CategoricalDtype): + if dtype.categories is None: + dtype = CategoricalDtype(values.categories, dtype.ordered) + elif not isinstance(values, (ABCIndex, ABCSeries, ExtensionArray)): + values = com.convert_to_list_like(values) + if isinstance(values, list) and len(values) == 0: + # By convention, empty lists result in object dtype: + values = np.array([], dtype=object) + elif isinstance(values, np.ndarray): + if values.ndim > 1: + # preempt sanitize_array from raising ValueError + raise NotImplementedError( + "> 1 ndim Categorical are not supported at this time" + ) + values = sanitize_array(values, None) + else: + # i.e. must be a list + arr = sanitize_array(values, None) + null_mask = isna(arr) + if null_mask.any(): + # We remove null values here, then below will re-insert + # them, grep "full_codes" + arr_list = [values[idx] for idx in np.where(~null_mask)[0]] + + # GH#44900 Do not cast to float if we have only missing values + if arr_list or arr.dtype == "object": + sanitize_dtype = None + else: + sanitize_dtype = arr.dtype + + arr = sanitize_array(arr_list, None, dtype=sanitize_dtype) + values = arr + + if dtype.categories is None: + if isinstance(values.dtype, ArrowDtype) and issubclass( + values.dtype.type, CategoricalDtypeType + ): + arr = values._pa_array.combine_chunks() + categories = arr.dictionary.to_pandas(types_mapper=ArrowDtype) + codes = arr.indices.to_numpy() + dtype = CategoricalDtype(categories, values.dtype.pyarrow_dtype.ordered) + else: + if not isinstance(values, ABCIndex): + # in particular RangeIndex xref test_index_equal_range_categories + values = sanitize_array(values, None) + try: + codes, categories = factorize(values, sort=True) + except TypeError as err: + codes, categories = factorize(values, sort=False) + if dtype.ordered: + # raise, as we don't have a sortable data structure and so + # the user should give us one by specifying categories + raise TypeError( + "'values' is not ordered, please " + "explicitly specify the categories order " + "by passing in a categories argument." + ) from err + + # we're inferring from values + dtype = CategoricalDtype(categories, dtype.ordered) + + elif isinstance(values.dtype, CategoricalDtype): + old_codes = extract_array(values)._codes + codes = recode_for_categories( + old_codes, values.dtype.categories, dtype.categories, copy=copy + ) + + else: + codes = _get_codes_for_values(values, dtype.categories) + + if null_mask.any(): + # Reinsert -1 placeholders for previously removed missing values + full_codes = -np.ones(null_mask.shape, dtype=codes.dtype) + full_codes[~null_mask] = codes + codes = full_codes + + dtype = CategoricalDtype(ordered=False).update_dtype(dtype) + arr = coerce_indexer_dtype(codes, dtype.categories) + super().__init__(arr, dtype) + + @property + def dtype(self) -> CategoricalDtype: + """ + The :class:`~pandas.api.types.CategoricalDtype` for this instance. + + Examples + -------- + >>> cat = pd.Categorical(['a', 'b'], ordered=True) + >>> cat + ['a', 'b'] + Categories (2, object): ['a' < 'b'] + >>> cat.dtype + CategoricalDtype(categories=['a', 'b'], ordered=True, categories_dtype=object) + """ + return self._dtype + + @property + def _internal_fill_value(self) -> int: + # using the specific numpy integer instead of python int to get + # the correct dtype back from _quantile in the all-NA case + dtype = self._ndarray.dtype + return dtype.type(-1) + + @classmethod + def _from_sequence( + cls, scalars, *, dtype: Dtype | None = None, copy: bool = False + ) -> Self: + return cls(scalars, dtype=dtype, copy=copy) + + @classmethod + def _from_scalars(cls, scalars, *, dtype: DtypeObj) -> Self: + if dtype is None: + # The _from_scalars strictness doesn't make much sense in this case. + raise NotImplementedError + + res = cls._from_sequence(scalars, dtype=dtype) + + # if there are any non-category elements in scalars, these will be + # converted to NAs in res. + mask = isna(scalars) + if not (mask == res.isna()).all(): + # Some non-category element in scalars got converted to NA in res. + raise ValueError + return res + + @overload + def astype(self, dtype: npt.DTypeLike, copy: bool = ...) -> np.ndarray: + ... + + @overload + def astype(self, dtype: ExtensionDtype, copy: bool = ...) -> ExtensionArray: + ... + + @overload + def astype(self, dtype: AstypeArg, copy: bool = ...) -> ArrayLike: + ... + + def astype(self, dtype: AstypeArg, copy: bool = True) -> ArrayLike: + """ + Coerce this type to another dtype + + Parameters + ---------- + dtype : numpy dtype or pandas type + copy : bool, default True + By default, astype always returns a newly allocated object. + If copy is set to False and dtype is categorical, the original + object is returned. + """ + dtype = pandas_dtype(dtype) + if self.dtype is dtype: + result = self.copy() if copy else self + + elif isinstance(dtype, CategoricalDtype): + # GH 10696/18593/18630 + dtype = self.dtype.update_dtype(dtype) + self = self.copy() if copy else self + result = self._set_dtype(dtype) + + elif isinstance(dtype, ExtensionDtype): + return super().astype(dtype, copy=copy) + + elif dtype.kind in "iu" and self.isna().any(): + raise ValueError("Cannot convert float NaN to integer") + + elif len(self.codes) == 0 or len(self.categories) == 0: + result = np.array( + self, + dtype=dtype, + copy=copy, + ) + + else: + # GH8628 (PERF): astype category codes instead of astyping array + new_cats = self.categories._values + + try: + new_cats = new_cats.astype(dtype=dtype, copy=copy) + fill_value = self.categories._na_value + if not is_valid_na_for_dtype(fill_value, dtype): + fill_value = lib.item_from_zerodim( + np.array(self.categories._na_value).astype(dtype) + ) + except ( + TypeError, # downstream error msg for CategoricalIndex is misleading + ValueError, + ): + msg = f"Cannot cast {self.categories.dtype} dtype to {dtype}" + raise ValueError(msg) + + result = take_nd( + new_cats, ensure_platform_int(self._codes), fill_value=fill_value + ) + + return result + + def to_list(self): + """ + Alias for tolist. + """ + # GH#51254 + warnings.warn( + "Categorical.to_list is deprecated and will be removed in a future " + "version. Use obj.tolist() instead", + FutureWarning, + stacklevel=find_stack_level(), + ) + return self.tolist() + + @classmethod + def _from_inferred_categories( + cls, inferred_categories, inferred_codes, dtype, true_values=None + ) -> Self: + """ + Construct a Categorical from inferred values. + + For inferred categories (`dtype` is None) the categories are sorted. + For explicit `dtype`, the `inferred_categories` are cast to the + appropriate type. + + Parameters + ---------- + inferred_categories : Index + inferred_codes : Index + dtype : CategoricalDtype or 'category' + true_values : list, optional + If none are provided, the default ones are + "True", "TRUE", and "true." + + Returns + ------- + Categorical + """ + from pandas import ( + Index, + to_datetime, + to_numeric, + to_timedelta, + ) + + cats = Index(inferred_categories) + known_categories = ( + isinstance(dtype, CategoricalDtype) and dtype.categories is not None + ) + + if known_categories: + # Convert to a specialized type with `dtype` if specified. + if is_any_real_numeric_dtype(dtype.categories.dtype): + cats = to_numeric(inferred_categories, errors="coerce") + elif lib.is_np_dtype(dtype.categories.dtype, "M"): + cats = to_datetime(inferred_categories, errors="coerce") + elif lib.is_np_dtype(dtype.categories.dtype, "m"): + cats = to_timedelta(inferred_categories, errors="coerce") + elif is_bool_dtype(dtype.categories.dtype): + if true_values is None: + true_values = ["True", "TRUE", "true"] + + # error: Incompatible types in assignment (expression has type + # "ndarray", variable has type "Index") + cats = cats.isin(true_values) # type: ignore[assignment] + + if known_categories: + # Recode from observation order to dtype.categories order. + categories = dtype.categories + codes = recode_for_categories(inferred_codes, cats, categories) + elif not cats.is_monotonic_increasing: + # Sort categories and recode for unknown categories. + unsorted = cats.copy() + categories = cats.sort_values() + + codes = recode_for_categories(inferred_codes, unsorted, categories) + dtype = CategoricalDtype(categories, ordered=False) + else: + dtype = CategoricalDtype(cats, ordered=False) + codes = inferred_codes + + return cls._simple_new(codes, dtype=dtype) + + @classmethod + def from_codes( + cls, + codes, + categories=None, + ordered=None, + dtype: Dtype | None = None, + validate: bool = True, + ) -> Self: + """ + Make a Categorical type from codes and categories or dtype. + + This constructor is useful if you already have codes and + categories/dtype and so do not need the (computation intensive) + factorization step, which is usually done on the constructor. + + If your data does not follow this convention, please use the normal + constructor. + + Parameters + ---------- + codes : array-like of int + An integer array, where each integer points to a category in + categories or dtype.categories, or else is -1 for NaN. + categories : index-like, optional + The categories for the categorical. Items need to be unique. + If the categories are not given here, then they must be provided + in `dtype`. + ordered : bool, optional + Whether or not this categorical is treated as an ordered + categorical. If not given here or in `dtype`, the resulting + categorical will be unordered. + dtype : CategoricalDtype or "category", optional + If :class:`CategoricalDtype`, cannot be used together with + `categories` or `ordered`. + validate : bool, default True + If True, validate that the codes are valid for the dtype. + If False, don't validate that the codes are valid. Be careful about skipping + validation, as invalid codes can lead to severe problems, such as segfaults. + + .. versionadded:: 2.1.0 + + Returns + ------- + Categorical + + Examples + -------- + >>> dtype = pd.CategoricalDtype(['a', 'b'], ordered=True) + >>> pd.Categorical.from_codes(codes=[0, 1, 0, 1], dtype=dtype) + ['a', 'b', 'a', 'b'] + Categories (2, object): ['a' < 'b'] + """ + dtype = CategoricalDtype._from_values_or_dtype( + categories=categories, ordered=ordered, dtype=dtype + ) + if dtype.categories is None: + msg = ( + "The categories must be provided in 'categories' or " + "'dtype'. Both were None." + ) + raise ValueError(msg) + + if validate: + # beware: non-valid codes may segfault + codes = cls._validate_codes_for_dtype(codes, dtype=dtype) + + return cls._simple_new(codes, dtype=dtype) + + # ------------------------------------------------------------------ + # Categories/Codes/Ordered + + @property + def categories(self) -> Index: + """ + The categories of this categorical. + + Setting assigns new values to each category (effectively a rename of + each individual category). + + The assigned value has to be a list-like object. All items must be + unique and the number of items in the new categories must be the same + as the number of items in the old categories. + + Raises + ------ + ValueError + If the new categories do not validate as categories or if the + number of new categories is unequal the number of old categories + + See Also + -------- + rename_categories : Rename categories. + reorder_categories : Reorder categories. + add_categories : Add new categories. + remove_categories : Remove the specified categories. + remove_unused_categories : Remove categories which are not used. + set_categories : Set the categories to the specified ones. + + Examples + -------- + For :class:`pandas.Series`: + + >>> ser = pd.Series(['a', 'b', 'c', 'a'], dtype='category') + >>> ser.cat.categories + Index(['a', 'b', 'c'], dtype='object') + + >>> raw_cat = pd.Categorical(['a', 'b', 'c', 'a'], categories=['b', 'c', 'd']) + >>> ser = pd.Series(raw_cat) + >>> ser.cat.categories + Index(['b', 'c', 'd'], dtype='object') + + For :class:`pandas.Categorical`: + + >>> cat = pd.Categorical(['a', 'b'], ordered=True) + >>> cat.categories + Index(['a', 'b'], dtype='object') + + For :class:`pandas.CategoricalIndex`: + + >>> ci = pd.CategoricalIndex(['a', 'c', 'b', 'a', 'c', 'b']) + >>> ci.categories + Index(['a', 'b', 'c'], dtype='object') + + >>> ci = pd.CategoricalIndex(['a', 'c'], categories=['c', 'b', 'a']) + >>> ci.categories + Index(['c', 'b', 'a'], dtype='object') + """ + return self.dtype.categories + + @property + def ordered(self) -> Ordered: + """ + Whether the categories have an ordered relationship. + + Examples + -------- + For :class:`pandas.Series`: + + >>> ser = pd.Series(['a', 'b', 'c', 'a'], dtype='category') + >>> ser.cat.ordered + False + + >>> raw_cat = pd.Categorical(['a', 'b', 'c', 'a'], ordered=True) + >>> ser = pd.Series(raw_cat) + >>> ser.cat.ordered + True + + For :class:`pandas.Categorical`: + + >>> cat = pd.Categorical(['a', 'b'], ordered=True) + >>> cat.ordered + True + + >>> cat = pd.Categorical(['a', 'b'], ordered=False) + >>> cat.ordered + False + + For :class:`pandas.CategoricalIndex`: + + >>> ci = pd.CategoricalIndex(['a', 'b'], ordered=True) + >>> ci.ordered + True + + >>> ci = pd.CategoricalIndex(['a', 'b'], ordered=False) + >>> ci.ordered + False + """ + return self.dtype.ordered + + @property + def codes(self) -> np.ndarray: + """ + The category codes of this categorical index. + + Codes are an array of integers which are the positions of the actual + values in the categories array. + + There is no setter, use the other categorical methods and the normal item + setter to change values in the categorical. + + Returns + ------- + ndarray[int] + A non-writable view of the ``codes`` array. + + Examples + -------- + For :class:`pandas.Categorical`: + + >>> cat = pd.Categorical(['a', 'b'], ordered=True) + >>> cat.codes + array([0, 1], dtype=int8) + + For :class:`pandas.CategoricalIndex`: + + >>> ci = pd.CategoricalIndex(['a', 'b', 'c', 'a', 'b', 'c']) + >>> ci.codes + array([0, 1, 2, 0, 1, 2], dtype=int8) + + >>> ci = pd.CategoricalIndex(['a', 'c'], categories=['c', 'b', 'a']) + >>> ci.codes + array([2, 0], dtype=int8) + """ + v = self._codes.view() + v.flags.writeable = False + return v + + def _set_categories(self, categories, fastpath: bool = False) -> None: + """ + Sets new categories inplace + + Parameters + ---------- + fastpath : bool, default False + Don't perform validation of the categories for uniqueness or nulls + + Examples + -------- + >>> c = pd.Categorical(['a', 'b']) + >>> c + ['a', 'b'] + Categories (2, object): ['a', 'b'] + + >>> c._set_categories(pd.Index(['a', 'c'])) + >>> c + ['a', 'c'] + Categories (2, object): ['a', 'c'] + """ + if fastpath: + new_dtype = CategoricalDtype._from_fastpath(categories, self.ordered) + else: + new_dtype = CategoricalDtype(categories, ordered=self.ordered) + if ( + not fastpath + and self.dtype.categories is not None + and len(new_dtype.categories) != len(self.dtype.categories) + ): + raise ValueError( + "new categories need to have the same number of " + "items as the old categories!" + ) + + super().__init__(self._ndarray, new_dtype) + + def _set_dtype(self, dtype: CategoricalDtype) -> Self: + """ + Internal method for directly updating the CategoricalDtype + + Parameters + ---------- + dtype : CategoricalDtype + + Notes + ----- + We don't do any validation here. It's assumed that the dtype is + a (valid) instance of `CategoricalDtype`. + """ + codes = recode_for_categories(self.codes, self.categories, dtype.categories) + return type(self)._simple_new(codes, dtype=dtype) + + def set_ordered(self, value: bool) -> Self: + """ + Set the ordered attribute to the boolean value. + + Parameters + ---------- + value : bool + Set whether this categorical is ordered (True) or not (False). + """ + new_dtype = CategoricalDtype(self.categories, ordered=value) + cat = self.copy() + NDArrayBacked.__init__(cat, cat._ndarray, new_dtype) + return cat + + def as_ordered(self) -> Self: + """ + Set the Categorical to be ordered. + + Returns + ------- + Categorical + Ordered Categorical. + + Examples + -------- + For :class:`pandas.Series`: + + >>> ser = pd.Series(['a', 'b', 'c', 'a'], dtype='category') + >>> ser.cat.ordered + False + >>> ser = ser.cat.as_ordered() + >>> ser.cat.ordered + True + + For :class:`pandas.CategoricalIndex`: + + >>> ci = pd.CategoricalIndex(['a', 'b', 'c', 'a']) + >>> ci.ordered + False + >>> ci = ci.as_ordered() + >>> ci.ordered + True + """ + return self.set_ordered(True) + + def as_unordered(self) -> Self: + """ + Set the Categorical to be unordered. + + Returns + ------- + Categorical + Unordered Categorical. + + Examples + -------- + For :class:`pandas.Series`: + + >>> raw_cat = pd.Categorical(['a', 'b', 'c', 'a'], ordered=True) + >>> ser = pd.Series(raw_cat) + >>> ser.cat.ordered + True + >>> ser = ser.cat.as_unordered() + >>> ser.cat.ordered + False + + For :class:`pandas.CategoricalIndex`: + + >>> ci = pd.CategoricalIndex(['a', 'b', 'c', 'a'], ordered=True) + >>> ci.ordered + True + >>> ci = ci.as_unordered() + >>> ci.ordered + False + """ + return self.set_ordered(False) + + def set_categories(self, new_categories, ordered=None, rename: bool = False): + """ + Set the categories to the specified new categories. + + ``new_categories`` can include new categories (which will result in + unused categories) or remove old categories (which results in values + set to ``NaN``). If ``rename=True``, the categories will simply be renamed + (less or more items than in old categories will result in values set to + ``NaN`` or in unused categories respectively). + + This method can be used to perform more than one action of adding, + removing, and reordering simultaneously and is therefore faster than + performing the individual steps via the more specialised methods. + + On the other hand this methods does not do checks (e.g., whether the + old categories are included in the new categories on a reorder), which + can result in surprising changes, for example when using special string + dtypes, which does not considers a S1 string equal to a single char + python string. + + Parameters + ---------- + new_categories : Index-like + The categories in new order. + ordered : bool, default False + Whether or not the categorical is treated as a ordered categorical. + If not given, do not change the ordered information. + rename : bool, default False + Whether or not the new_categories should be considered as a rename + of the old categories or as reordered categories. + + Returns + ------- + Categorical with reordered categories. + + Raises + ------ + ValueError + If new_categories does not validate as categories + + See Also + -------- + rename_categories : Rename categories. + reorder_categories : Reorder categories. + add_categories : Add new categories. + remove_categories : Remove the specified categories. + remove_unused_categories : Remove categories which are not used. + + Examples + -------- + For :class:`pandas.Series`: + + >>> raw_cat = pd.Categorical(['a', 'b', 'c', 'A'], + ... categories=['a', 'b', 'c'], ordered=True) + >>> ser = pd.Series(raw_cat) + >>> ser + 0 a + 1 b + 2 c + 3 NaN + dtype: category + Categories (3, object): ['a' < 'b' < 'c'] + + >>> ser.cat.set_categories(['A', 'B', 'C'], rename=True) + 0 A + 1 B + 2 C + 3 NaN + dtype: category + Categories (3, object): ['A' < 'B' < 'C'] + + For :class:`pandas.CategoricalIndex`: + + >>> ci = pd.CategoricalIndex(['a', 'b', 'c', 'A'], + ... categories=['a', 'b', 'c'], ordered=True) + >>> ci + CategoricalIndex(['a', 'b', 'c', nan], categories=['a', 'b', 'c'], + ordered=True, dtype='category') + + >>> ci.set_categories(['A', 'b', 'c']) + CategoricalIndex([nan, 'b', 'c', nan], categories=['A', 'b', 'c'], + ordered=True, dtype='category') + >>> ci.set_categories(['A', 'b', 'c'], rename=True) + CategoricalIndex(['A', 'b', 'c', nan], categories=['A', 'b', 'c'], + ordered=True, dtype='category') + """ + + if ordered is None: + ordered = self.dtype.ordered + new_dtype = CategoricalDtype(new_categories, ordered=ordered) + + cat = self.copy() + if rename: + if cat.dtype.categories is not None and len(new_dtype.categories) < len( + cat.dtype.categories + ): + # remove all _codes which are larger and set to -1/NaN + cat._codes[cat._codes >= len(new_dtype.categories)] = -1 + codes = cat._codes + else: + codes = recode_for_categories( + cat.codes, cat.categories, new_dtype.categories + ) + NDArrayBacked.__init__(cat, codes, new_dtype) + return cat + + def rename_categories(self, new_categories) -> Self: + """ + Rename categories. + + Parameters + ---------- + new_categories : list-like, dict-like or callable + + New categories which will replace old categories. + + * list-like: all items must be unique and the number of items in + the new categories must match the existing number of categories. + + * dict-like: specifies a mapping from + old categories to new. Categories not contained in the mapping + are passed through and extra categories in the mapping are + ignored. + + * callable : a callable that is called on all items in the old + categories and whose return values comprise the new categories. + + Returns + ------- + Categorical + Categorical with renamed categories. + + Raises + ------ + ValueError + If new categories are list-like and do not have the same number of + items than the current categories or do not validate as categories + + See Also + -------- + reorder_categories : Reorder categories. + add_categories : Add new categories. + remove_categories : Remove the specified categories. + remove_unused_categories : Remove categories which are not used. + set_categories : Set the categories to the specified ones. + + Examples + -------- + >>> c = pd.Categorical(['a', 'a', 'b']) + >>> c.rename_categories([0, 1]) + [0, 0, 1] + Categories (2, int64): [0, 1] + + For dict-like ``new_categories``, extra keys are ignored and + categories not in the dictionary are passed through + + >>> c.rename_categories({'a': 'A', 'c': 'C'}) + ['A', 'A', 'b'] + Categories (2, object): ['A', 'b'] + + You may also provide a callable to create the new categories + + >>> c.rename_categories(lambda x: x.upper()) + ['A', 'A', 'B'] + Categories (2, object): ['A', 'B'] + """ + + if is_dict_like(new_categories): + new_categories = [ + new_categories.get(item, item) for item in self.categories + ] + elif callable(new_categories): + new_categories = [new_categories(item) for item in self.categories] + + cat = self.copy() + cat._set_categories(new_categories) + return cat + + def reorder_categories(self, new_categories, ordered=None) -> Self: + """ + Reorder categories as specified in new_categories. + + ``new_categories`` need to include all old categories and no new category + items. + + Parameters + ---------- + new_categories : Index-like + The categories in new order. + ordered : bool, optional + Whether or not the categorical is treated as a ordered categorical. + If not given, do not change the ordered information. + + Returns + ------- + Categorical + Categorical with reordered categories. + + Raises + ------ + ValueError + If the new categories do not contain all old category items or any + new ones + + See Also + -------- + rename_categories : Rename categories. + add_categories : Add new categories. + remove_categories : Remove the specified categories. + remove_unused_categories : Remove categories which are not used. + set_categories : Set the categories to the specified ones. + + Examples + -------- + For :class:`pandas.Series`: + + >>> ser = pd.Series(['a', 'b', 'c', 'a'], dtype='category') + >>> ser = ser.cat.reorder_categories(['c', 'b', 'a'], ordered=True) + >>> ser + 0 a + 1 b + 2 c + 3 a + dtype: category + Categories (3, object): ['c' < 'b' < 'a'] + + >>> ser.sort_values() + 2 c + 1 b + 0 a + 3 a + dtype: category + Categories (3, object): ['c' < 'b' < 'a'] + + For :class:`pandas.CategoricalIndex`: + + >>> ci = pd.CategoricalIndex(['a', 'b', 'c', 'a']) + >>> ci + CategoricalIndex(['a', 'b', 'c', 'a'], categories=['a', 'b', 'c'], + ordered=False, dtype='category') + >>> ci.reorder_categories(['c', 'b', 'a'], ordered=True) + CategoricalIndex(['a', 'b', 'c', 'a'], categories=['c', 'b', 'a'], + ordered=True, dtype='category') + """ + if ( + len(self.categories) != len(new_categories) + or not self.categories.difference(new_categories).empty + ): + raise ValueError( + "items in new_categories are not the same as in old categories" + ) + return self.set_categories(new_categories, ordered=ordered) + + def add_categories(self, new_categories) -> Self: + """ + Add new categories. + + `new_categories` will be included at the last/highest place in the + categories and will be unused directly after this call. + + Parameters + ---------- + new_categories : category or list-like of category + The new categories to be included. + + Returns + ------- + Categorical + Categorical with new categories added. + + Raises + ------ + ValueError + If the new categories include old categories or do not validate as + categories + + See Also + -------- + rename_categories : Rename categories. + reorder_categories : Reorder categories. + remove_categories : Remove the specified categories. + remove_unused_categories : Remove categories which are not used. + set_categories : Set the categories to the specified ones. + + Examples + -------- + >>> c = pd.Categorical(['c', 'b', 'c']) + >>> c + ['c', 'b', 'c'] + Categories (2, object): ['b', 'c'] + + >>> c.add_categories(['d', 'a']) + ['c', 'b', 'c'] + Categories (4, object): ['b', 'c', 'd', 'a'] + """ + + if not is_list_like(new_categories): + new_categories = [new_categories] + already_included = set(new_categories) & set(self.dtype.categories) + if len(already_included) != 0: + raise ValueError( + f"new categories must not include old categories: {already_included}" + ) + + if hasattr(new_categories, "dtype"): + from pandas import Series + + dtype = find_common_type( + [self.dtype.categories.dtype, new_categories.dtype] + ) + new_categories = Series( + list(self.dtype.categories) + list(new_categories), dtype=dtype + ) + else: + new_categories = list(self.dtype.categories) + list(new_categories) + + new_dtype = CategoricalDtype(new_categories, self.ordered) + cat = self.copy() + codes = coerce_indexer_dtype(cat._ndarray, new_dtype.categories) + NDArrayBacked.__init__(cat, codes, new_dtype) + return cat + + def remove_categories(self, removals) -> Self: + """ + Remove the specified categories. + + `removals` must be included in the old categories. Values which were in + the removed categories will be set to NaN + + Parameters + ---------- + removals : category or list of categories + The categories which should be removed. + + Returns + ------- + Categorical + Categorical with removed categories. + + Raises + ------ + ValueError + If the removals are not contained in the categories + + See Also + -------- + rename_categories : Rename categories. + reorder_categories : Reorder categories. + add_categories : Add new categories. + remove_unused_categories : Remove categories which are not used. + set_categories : Set the categories to the specified ones. + + Examples + -------- + >>> c = pd.Categorical(['a', 'c', 'b', 'c', 'd']) + >>> c + ['a', 'c', 'b', 'c', 'd'] + Categories (4, object): ['a', 'b', 'c', 'd'] + + >>> c.remove_categories(['d', 'a']) + [NaN, 'c', 'b', 'c', NaN] + Categories (2, object): ['b', 'c'] + """ + from pandas import Index + + if not is_list_like(removals): + removals = [removals] + + removals = Index(removals).unique().dropna() + new_categories = ( + self.dtype.categories.difference(removals, sort=False) + if self.dtype.ordered is True + else self.dtype.categories.difference(removals) + ) + not_included = removals.difference(self.dtype.categories) + + if len(not_included) != 0: + not_included = set(not_included) + raise ValueError(f"removals must all be in old categories: {not_included}") + + return self.set_categories(new_categories, ordered=self.ordered, rename=False) + + def remove_unused_categories(self) -> Self: + """ + Remove categories which are not used. + + Returns + ------- + Categorical + Categorical with unused categories dropped. + + See Also + -------- + rename_categories : Rename categories. + reorder_categories : Reorder categories. + add_categories : Add new categories. + remove_categories : Remove the specified categories. + set_categories : Set the categories to the specified ones. + + Examples + -------- + >>> c = pd.Categorical(['a', 'c', 'b', 'c', 'd']) + >>> c + ['a', 'c', 'b', 'c', 'd'] + Categories (4, object): ['a', 'b', 'c', 'd'] + + >>> c[2] = 'a' + >>> c[4] = 'c' + >>> c + ['a', 'c', 'a', 'c', 'c'] + Categories (4, object): ['a', 'b', 'c', 'd'] + + >>> c.remove_unused_categories() + ['a', 'c', 'a', 'c', 'c'] + Categories (2, object): ['a', 'c'] + """ + idx, inv = np.unique(self._codes, return_inverse=True) + + if idx.size != 0 and idx[0] == -1: # na sentinel + idx, inv = idx[1:], inv - 1 + + new_categories = self.dtype.categories.take(idx) + new_dtype = CategoricalDtype._from_fastpath( + new_categories, ordered=self.ordered + ) + new_codes = coerce_indexer_dtype(inv, new_dtype.categories) + + cat = self.copy() + NDArrayBacked.__init__(cat, new_codes, new_dtype) + return cat + + # ------------------------------------------------------------------ + + def map( + self, + mapper, + na_action: Literal["ignore"] | None | lib.NoDefault = lib.no_default, + ): + """ + Map categories using an input mapping or function. + + Maps the categories to new categories. If the mapping correspondence is + one-to-one the result is a :class:`~pandas.Categorical` which has the + same order property as the original, otherwise a :class:`~pandas.Index` + is returned. NaN values are unaffected. + + If a `dict` or :class:`~pandas.Series` is used any unmapped category is + mapped to `NaN`. Note that if this happens an :class:`~pandas.Index` + will be returned. + + Parameters + ---------- + mapper : function, dict, or Series + Mapping correspondence. + na_action : {None, 'ignore'}, default 'ignore' + If 'ignore', propagate NaN values, without passing them to the + mapping correspondence. + + .. deprecated:: 2.1.0 + + The default value of 'ignore' has been deprecated and will be changed to + None in the future. + + Returns + ------- + pandas.Categorical or pandas.Index + Mapped categorical. + + See Also + -------- + CategoricalIndex.map : Apply a mapping correspondence on a + :class:`~pandas.CategoricalIndex`. + Index.map : Apply a mapping correspondence on an + :class:`~pandas.Index`. + Series.map : Apply a mapping correspondence on a + :class:`~pandas.Series`. + Series.apply : Apply more complex functions on a + :class:`~pandas.Series`. + + Examples + -------- + >>> cat = pd.Categorical(['a', 'b', 'c']) + >>> cat + ['a', 'b', 'c'] + Categories (3, object): ['a', 'b', 'c'] + >>> cat.map(lambda x: x.upper(), na_action=None) + ['A', 'B', 'C'] + Categories (3, object): ['A', 'B', 'C'] + >>> cat.map({'a': 'first', 'b': 'second', 'c': 'third'}, na_action=None) + ['first', 'second', 'third'] + Categories (3, object): ['first', 'second', 'third'] + + If the mapping is one-to-one the ordering of the categories is + preserved: + + >>> cat = pd.Categorical(['a', 'b', 'c'], ordered=True) + >>> cat + ['a', 'b', 'c'] + Categories (3, object): ['a' < 'b' < 'c'] + >>> cat.map({'a': 3, 'b': 2, 'c': 1}, na_action=None) + [3, 2, 1] + Categories (3, int64): [3 < 2 < 1] + + If the mapping is not one-to-one an :class:`~pandas.Index` is returned: + + >>> cat.map({'a': 'first', 'b': 'second', 'c': 'first'}, na_action=None) + Index(['first', 'second', 'first'], dtype='object') + + If a `dict` is used, all unmapped categories are mapped to `NaN` and + the result is an :class:`~pandas.Index`: + + >>> cat.map({'a': 'first', 'b': 'second'}, na_action=None) + Index(['first', 'second', nan], dtype='object') + """ + if na_action is lib.no_default: + warnings.warn( + "The default value of 'ignore' for the `na_action` parameter in " + "pandas.Categorical.map is deprecated and will be " + "changed to 'None' in a future version. Please set na_action to the " + "desired value to avoid seeing this warning", + FutureWarning, + stacklevel=find_stack_level(), + ) + na_action = "ignore" + + assert callable(mapper) or is_dict_like(mapper) + + new_categories = self.categories.map(mapper) + + has_nans = np.any(self._codes == -1) + + na_val = np.nan + if na_action is None and has_nans: + na_val = mapper(np.nan) if callable(mapper) else mapper.get(np.nan, np.nan) + + if new_categories.is_unique and not new_categories.hasnans and na_val is np.nan: + new_dtype = CategoricalDtype(new_categories, ordered=self.ordered) + return self.from_codes(self._codes.copy(), dtype=new_dtype, validate=False) + + if has_nans: + new_categories = new_categories.insert(len(new_categories), na_val) + + return np.take(new_categories, self._codes) + + __eq__ = _cat_compare_op(operator.eq) + __ne__ = _cat_compare_op(operator.ne) + __lt__ = _cat_compare_op(operator.lt) + __gt__ = _cat_compare_op(operator.gt) + __le__ = _cat_compare_op(operator.le) + __ge__ = _cat_compare_op(operator.ge) + + # ------------------------------------------------------------- + # Validators; ideally these can be de-duplicated + + def _validate_setitem_value(self, value): + if not is_hashable(value): + # wrap scalars and hashable-listlikes in list + return self._validate_listlike(value) + else: + return self._validate_scalar(value) + + def _validate_scalar(self, fill_value): + """ + Convert a user-facing fill_value to a representation to use with our + underlying ndarray, raising TypeError if this is not possible. + + Parameters + ---------- + fill_value : object + + Returns + ------- + fill_value : int + + Raises + ------ + TypeError + """ + + if is_valid_na_for_dtype(fill_value, self.categories.dtype): + fill_value = -1 + elif fill_value in self.categories: + fill_value = self._unbox_scalar(fill_value) + else: + raise TypeError( + "Cannot setitem on a Categorical with a new " + f"category ({fill_value}), set the categories first" + ) from None + return fill_value + + @classmethod + def _validate_codes_for_dtype(cls, codes, *, dtype: CategoricalDtype) -> np.ndarray: + if isinstance(codes, ExtensionArray) and is_integer_dtype(codes.dtype): + # Avoid the implicit conversion of Int to object + if isna(codes).any(): + raise ValueError("codes cannot contain NA values") + codes = codes.to_numpy(dtype=np.int64) + else: + codes = np.asarray(codes) + if len(codes) and codes.dtype.kind not in "iu": + raise ValueError("codes need to be array-like integers") + + if len(codes) and (codes.max() >= len(dtype.categories) or codes.min() < -1): + raise ValueError("codes need to be between -1 and len(categories)-1") + return codes + + # ------------------------------------------------------------- + + @ravel_compat + def __array__( + self, dtype: NpDtype | None = None, copy: bool | None = None + ) -> np.ndarray: + """ + The numpy array interface. + + Returns + ------- + numpy.array + A numpy array of either the specified dtype or, + if dtype==None (default), the same dtype as + categorical.categories.dtype. + + Examples + -------- + + >>> cat = pd.Categorical(['a', 'b'], ordered=True) + + The following calls ``cat.__array__`` + + >>> np.asarray(cat) + array(['a', 'b'], dtype=object) + """ + ret = take_nd(self.categories._values, self._codes) + if dtype and np.dtype(dtype) != self.categories.dtype: + return np.asarray(ret, dtype) + # When we're a Categorical[ExtensionArray], like Interval, + # we need to ensure __array__ gets all the way to an + # ndarray. + return np.asarray(ret) + + def __array_ufunc__(self, ufunc: np.ufunc, method: str, *inputs, **kwargs): + # for binary ops, use our custom dunder methods + result = arraylike.maybe_dispatch_ufunc_to_dunder_op( + self, ufunc, method, *inputs, **kwargs + ) + if result is not NotImplemented: + return result + + if "out" in kwargs: + # e.g. test_numpy_ufuncs_out + return arraylike.dispatch_ufunc_with_out( + self, ufunc, method, *inputs, **kwargs + ) + + if method == "reduce": + # e.g. TestCategoricalAnalytics::test_min_max_ordered + result = arraylike.dispatch_reduction_ufunc( + self, ufunc, method, *inputs, **kwargs + ) + if result is not NotImplemented: + return result + + # for all other cases, raise for now (similarly as what happens in + # Series.__array_prepare__) + raise TypeError( + f"Object with dtype {self.dtype} cannot perform " + f"the numpy op {ufunc.__name__}" + ) + + def __setstate__(self, state) -> None: + """Necessary for making this object picklable""" + if not isinstance(state, dict): + return super().__setstate__(state) + + if "_dtype" not in state: + state["_dtype"] = CategoricalDtype(state["_categories"], state["_ordered"]) + + if "_codes" in state and "_ndarray" not in state: + # backward compat, changed what is property vs attribute + state["_ndarray"] = state.pop("_codes") + + super().__setstate__(state) + + @property + def nbytes(self) -> int: + return self._codes.nbytes + self.dtype.categories.values.nbytes + + def memory_usage(self, deep: bool = False) -> int: + """ + Memory usage of my values + + Parameters + ---------- + deep : bool + Introspect the data deeply, interrogate + `object` dtypes for system-level memory consumption + + Returns + ------- + bytes used + + Notes + ----- + Memory usage does not include memory consumed by elements that + are not components of the array if deep=False + + See Also + -------- + numpy.ndarray.nbytes + """ + return self._codes.nbytes + self.dtype.categories.memory_usage(deep=deep) + + def isna(self) -> npt.NDArray[np.bool_]: + """ + Detect missing values + + Missing values (-1 in .codes) are detected. + + Returns + ------- + np.ndarray[bool] of whether my values are null + + See Also + -------- + isna : Top-level isna. + isnull : Alias of isna. + Categorical.notna : Boolean inverse of Categorical.isna. + + """ + return self._codes == -1 + + isnull = isna + + def notna(self) -> npt.NDArray[np.bool_]: + """ + Inverse of isna + + Both missing values (-1 in .codes) and NA as a category are detected as + null. + + Returns + ------- + np.ndarray[bool] of whether my values are not null + + See Also + -------- + notna : Top-level notna. + notnull : Alias of notna. + Categorical.isna : Boolean inverse of Categorical.notna. + + """ + return ~self.isna() + + notnull = notna + + def value_counts(self, dropna: bool = True) -> Series: + """ + Return a Series containing counts of each category. + + Every category will have an entry, even those with a count of 0. + + Parameters + ---------- + dropna : bool, default True + Don't include counts of NaN. + + Returns + ------- + counts : Series + + See Also + -------- + Series.value_counts + """ + from pandas import ( + CategoricalIndex, + Series, + ) + + code, cat = self._codes, self.categories + ncat, mask = (len(cat), code >= 0) + ix, clean = np.arange(ncat), mask.all() + + if dropna or clean: + obs = code if clean else code[mask] + count = np.bincount(obs, minlength=ncat or 0) + else: + count = np.bincount(np.where(mask, code, ncat)) + ix = np.append(ix, -1) + + ix = coerce_indexer_dtype(ix, self.dtype.categories) + ix = self._from_backing_data(ix) + + return Series( + count, index=CategoricalIndex(ix), dtype="int64", name="count", copy=False + ) + + # error: Argument 2 of "_empty" is incompatible with supertype + # "NDArrayBackedExtensionArray"; supertype defines the argument type as + # "ExtensionDtype" + @classmethod + def _empty( # type: ignore[override] + cls, shape: Shape, dtype: CategoricalDtype + ) -> Self: + """ + Analogous to np.empty(shape, dtype=dtype) + + Parameters + ---------- + shape : tuple[int] + dtype : CategoricalDtype + """ + arr = cls._from_sequence([], dtype=dtype) + + # We have to use np.zeros instead of np.empty otherwise the resulting + # ndarray may contain codes not supported by this dtype, in which + # case repr(result) could segfault. + backing = np.zeros(shape, dtype=arr._ndarray.dtype) + + return arr._from_backing_data(backing) + + def _internal_get_values(self) -> ArrayLike: + """ + Return the values. + + For internal compatibility with pandas formatting. + + Returns + ------- + np.ndarray or ExtensionArray + A numpy array or ExtensionArray of the same dtype as + categorical.categories.dtype. + """ + # if we are a datetime and period index, return Index to keep metadata + if needs_i8_conversion(self.categories.dtype): + return self.categories.take(self._codes, fill_value=NaT)._values + elif is_integer_dtype(self.categories.dtype) and -1 in self._codes: + return ( + self.categories.astype("object") + .take(self._codes, fill_value=np.nan) + ._values + ) + return np.array(self) + + def check_for_ordered(self, op) -> None: + """assert that we are ordered""" + if not self.ordered: + raise TypeError( + f"Categorical is not ordered for operation {op}\n" + "you can use .as_ordered() to change the " + "Categorical to an ordered one\n" + ) + + def argsort( + self, *, ascending: bool = True, kind: SortKind = "quicksort", **kwargs + ): + """ + Return the indices that would sort the Categorical. + + Missing values are sorted at the end. + + Parameters + ---------- + ascending : bool, default True + Whether the indices should result in an ascending + or descending sort. + kind : {'quicksort', 'mergesort', 'heapsort', 'stable'}, optional + Sorting algorithm. + **kwargs: + passed through to :func:`numpy.argsort`. + + Returns + ------- + np.ndarray[np.intp] + + See Also + -------- + numpy.ndarray.argsort + + Notes + ----- + While an ordering is applied to the category values, arg-sorting + in this context refers more to organizing and grouping together + based on matching category values. Thus, this function can be + called on an unordered Categorical instance unlike the functions + 'Categorical.min' and 'Categorical.max'. + + Examples + -------- + >>> pd.Categorical(['b', 'b', 'a', 'c']).argsort() + array([2, 0, 1, 3]) + + >>> cat = pd.Categorical(['b', 'b', 'a', 'c'], + ... categories=['c', 'b', 'a'], + ... ordered=True) + >>> cat.argsort() + array([3, 0, 1, 2]) + + Missing values are placed at the end + + >>> cat = pd.Categorical([2, None, 1]) + >>> cat.argsort() + array([2, 0, 1]) + """ + return super().argsort(ascending=ascending, kind=kind, **kwargs) + + @overload + def sort_values( + self, + *, + inplace: Literal[False] = ..., + ascending: bool = ..., + na_position: str = ..., + ) -> Self: + ... + + @overload + def sort_values( + self, *, inplace: Literal[True], ascending: bool = ..., na_position: str = ... + ) -> None: + ... + + def sort_values( + self, + *, + inplace: bool = False, + ascending: bool = True, + na_position: str = "last", + ) -> Self | None: + """ + Sort the Categorical by category value returning a new + Categorical by default. + + While an ordering is applied to the category values, sorting in this + context refers more to organizing and grouping together based on + matching category values. Thus, this function can be called on an + unordered Categorical instance unlike the functions 'Categorical.min' + and 'Categorical.max'. + + Parameters + ---------- + inplace : bool, default False + Do operation in place. + ascending : bool, default True + Order ascending. Passing False orders descending. The + ordering parameter provides the method by which the + category values are organized. + na_position : {'first', 'last'} (optional, default='last') + 'first' puts NaNs at the beginning + 'last' puts NaNs at the end + + Returns + ------- + Categorical or None + + See Also + -------- + Categorical.sort + Series.sort_values + + Examples + -------- + >>> c = pd.Categorical([1, 2, 2, 1, 5]) + >>> c + [1, 2, 2, 1, 5] + Categories (3, int64): [1, 2, 5] + >>> c.sort_values() + [1, 1, 2, 2, 5] + Categories (3, int64): [1, 2, 5] + >>> c.sort_values(ascending=False) + [5, 2, 2, 1, 1] + Categories (3, int64): [1, 2, 5] + + >>> c = pd.Categorical([1, 2, 2, 1, 5]) + + 'sort_values' behaviour with NaNs. Note that 'na_position' + is independent of the 'ascending' parameter: + + >>> c = pd.Categorical([np.nan, 2, 2, np.nan, 5]) + >>> c + [NaN, 2, 2, NaN, 5] + Categories (2, int64): [2, 5] + >>> c.sort_values() + [2, 2, 5, NaN, NaN] + Categories (2, int64): [2, 5] + >>> c.sort_values(ascending=False) + [5, 2, 2, NaN, NaN] + Categories (2, int64): [2, 5] + >>> c.sort_values(na_position='first') + [NaN, NaN, 2, 2, 5] + Categories (2, int64): [2, 5] + >>> c.sort_values(ascending=False, na_position='first') + [NaN, NaN, 5, 2, 2] + Categories (2, int64): [2, 5] + """ + inplace = validate_bool_kwarg(inplace, "inplace") + if na_position not in ["last", "first"]: + raise ValueError(f"invalid na_position: {repr(na_position)}") + + sorted_idx = nargsort(self, ascending=ascending, na_position=na_position) + + if not inplace: + codes = self._codes[sorted_idx] + return self._from_backing_data(codes) + self._codes[:] = self._codes[sorted_idx] + return None + + def _rank( + self, + *, + axis: AxisInt = 0, + method: str = "average", + na_option: str = "keep", + ascending: bool = True, + pct: bool = False, + ): + """ + See Series.rank.__doc__. + """ + if axis != 0: + raise NotImplementedError + vff = self._values_for_rank() + return algorithms.rank( + vff, + axis=axis, + method=method, + na_option=na_option, + ascending=ascending, + pct=pct, + ) + + def _values_for_rank(self) -> np.ndarray: + """ + For correctly ranking ordered categorical data. See GH#15420 + + Ordered categorical data should be ranked on the basis of + codes with -1 translated to NaN. + + Returns + ------- + numpy.array + + """ + from pandas import Series + + if self.ordered: + values = self.codes + mask = values == -1 + if mask.any(): + values = values.astype("float64") + values[mask] = np.nan + elif is_any_real_numeric_dtype(self.categories.dtype): + values = np.array(self) + else: + # reorder the categories (so rank can use the float codes) + # instead of passing an object array to rank + values = np.array( + self.rename_categories( + Series(self.categories, copy=False).rank().values + ) + ) + return values + + def _hash_pandas_object( + self, *, encoding: str, hash_key: str, categorize: bool + ) -> npt.NDArray[np.uint64]: + """ + Hash a Categorical by hashing its categories, and then mapping the codes + to the hashes. + + Parameters + ---------- + encoding : str + hash_key : str + categorize : bool + Ignored for Categorical. + + Returns + ------- + np.ndarray[uint64] + """ + # Note we ignore categorize, as we are already Categorical. + from pandas.core.util.hashing import hash_array + + # Convert ExtensionArrays to ndarrays + values = np.asarray(self.categories._values) + hashed = hash_array(values, encoding, hash_key, categorize=False) + + # we have uint64, as we don't directly support missing values + # we don't want to use take_nd which will coerce to float + # instead, directly construct the result with a + # max(np.uint64) as the missing value indicator + # + # TODO: GH#15362 + + mask = self.isna() + if len(hashed): + result = hashed.take(self._codes) + else: + result = np.zeros(len(mask), dtype="uint64") + + if mask.any(): + result[mask] = lib.u8max + + return result + + # ------------------------------------------------------------------ + # NDArrayBackedExtensionArray compat + + @property + def _codes(self) -> np.ndarray: + return self._ndarray + + def _box_func(self, i: int): + if i == -1: + return np.nan + return self.categories[i] + + def _unbox_scalar(self, key) -> int: + # searchsorted is very performance sensitive. By converting codes + # to same dtype as self.codes, we get much faster performance. + code = self.categories.get_loc(key) + code = self._ndarray.dtype.type(code) + return code + + # ------------------------------------------------------------------ + + def __iter__(self) -> Iterator: + """ + Returns an Iterator over the values of this Categorical. + """ + if self.ndim == 1: + return iter(self._internal_get_values().tolist()) + else: + return (self[n] for n in range(len(self))) + + def __contains__(self, key) -> bool: + """ + Returns True if `key` is in this Categorical. + """ + # if key is a NaN, check if any NaN is in self. + if is_valid_na_for_dtype(key, self.categories.dtype): + return bool(self.isna().any()) + + return contains(self, key, container=self._codes) + + # ------------------------------------------------------------------ + # Rendering Methods + + def _formatter(self, boxed: bool = False): + # Returning None here will cause format_array to do inference. + return None + + def _repr_categories(self) -> list[str]: + """ + return the base repr for the categories + """ + max_categories = ( + 10 + if get_option("display.max_categories") == 0 + else get_option("display.max_categories") + ) + from pandas.io.formats import format as fmt + + format_array = partial( + fmt.format_array, formatter=None, quoting=QUOTE_NONNUMERIC + ) + if len(self.categories) > max_categories: + num = max_categories // 2 + head = format_array(self.categories[:num]._values) + tail = format_array(self.categories[-num:]._values) + category_strs = head + ["..."] + tail + else: + category_strs = format_array(self.categories._values) + + # Strip all leading spaces, which format_array adds for columns... + category_strs = [x.strip() for x in category_strs] + return category_strs + + def _get_repr_footer(self) -> str: + """ + Returns a string representation of the footer. + """ + category_strs = self._repr_categories() + dtype = str(self.categories.dtype) + levheader = f"Categories ({len(self.categories)}, {dtype}): " + width, _ = get_terminal_size() + max_width = get_option("display.width") or width + if console.in_ipython_frontend(): + # 0 = no breaks + max_width = 0 + levstring = "" + start = True + cur_col_len = len(levheader) # header + sep_len, sep = (3, " < ") if self.ordered else (2, ", ") + linesep = f"{sep.rstrip()}\n" # remove whitespace + for val in category_strs: + if max_width != 0 and cur_col_len + sep_len + len(val) > max_width: + levstring += linesep + (" " * (len(levheader) + 1)) + cur_col_len = len(levheader) + 1 # header + a whitespace + elif not start: + levstring += sep + cur_col_len += len(val) + levstring += val + start = False + # replace to simple save space by + return f"{levheader}[{levstring.replace(' < ... < ', ' ... ')}]" + + def _get_values_repr(self) -> str: + from pandas.io.formats import format as fmt + + assert len(self) > 0 + + vals = self._internal_get_values() + fmt_values = fmt.format_array( + vals, + None, + float_format=None, + na_rep="NaN", + quoting=QUOTE_NONNUMERIC, + ) + + fmt_values = [i.strip() for i in fmt_values] + joined = ", ".join(fmt_values) + result = "[" + joined + "]" + return result + + def __repr__(self) -> str: + """ + String representation. + """ + footer = self._get_repr_footer() + length = len(self) + max_len = 10 + if length > max_len: + # In long cases we do not display all entries, so we add Length + # information to the __repr__. + num = max_len // 2 + head = self[:num]._get_values_repr() + tail = self[-(max_len - num) :]._get_values_repr() + body = f"{head[:-1]}, ..., {tail[1:]}" + length_info = f"Length: {len(self)}" + result = f"{body}\n{length_info}\n{footer}" + elif length > 0: + body = self._get_values_repr() + result = f"{body}\n{footer}" + else: + # In the empty case we use a comma instead of newline to get + # a more compact __repr__ + body = "[]" + result = f"{body}, {footer}" + + return result + + # ------------------------------------------------------------------ + + def _validate_listlike(self, value): + # NB: here we assume scalar-like tuples have already been excluded + value = extract_array(value, extract_numpy=True) + + # require identical categories set + if isinstance(value, Categorical): + if self.dtype != value.dtype: + raise TypeError( + "Cannot set a Categorical with another, " + "without identical categories" + ) + # dtype equality implies categories_match_up_to_permutation + value = self._encode_with_my_categories(value) + return value._codes + + from pandas import Index + + # tupleize_cols=False for e.g. test_fillna_iterable_category GH#41914 + to_add = Index._with_infer(value, tupleize_cols=False).difference( + self.categories + ) + + # no assignments of values not in categories, but it's always ok to set + # something to np.nan + if len(to_add) and not isna(to_add).all(): + raise TypeError( + "Cannot setitem on a Categorical with a new " + "category, set the categories first" + ) + + codes = self.categories.get_indexer(value) + return codes.astype(self._ndarray.dtype, copy=False) + + def _reverse_indexer(self) -> dict[Hashable, npt.NDArray[np.intp]]: + """ + Compute the inverse of a categorical, returning + a dict of categories -> indexers. + + *This is an internal function* + + Returns + ------- + Dict[Hashable, np.ndarray[np.intp]] + dict of categories -> indexers + + Examples + -------- + >>> c = pd.Categorical(list('aabca')) + >>> c + ['a', 'a', 'b', 'c', 'a'] + Categories (3, object): ['a', 'b', 'c'] + >>> c.categories + Index(['a', 'b', 'c'], dtype='object') + >>> c.codes + array([0, 0, 1, 2, 0], dtype=int8) + >>> c._reverse_indexer() + {'a': array([0, 1, 4]), 'b': array([2]), 'c': array([3])} + + """ + categories = self.categories + r, counts = libalgos.groupsort_indexer( + ensure_platform_int(self.codes), categories.size + ) + counts = ensure_int64(counts).cumsum() + _result = (r[start:end] for start, end in zip(counts, counts[1:])) + return dict(zip(categories, _result)) + + # ------------------------------------------------------------------ + # Reductions + + def _reduce( + self, name: str, *, skipna: bool = True, keepdims: bool = False, **kwargs + ): + result = super()._reduce(name, skipna=skipna, keepdims=keepdims, **kwargs) + if name in ["argmax", "argmin"]: + # don't wrap in Categorical! + return result + if keepdims: + return type(self)(result, dtype=self.dtype) + else: + return result + + def min(self, *, skipna: bool = True, **kwargs): + """ + The minimum value of the object. + + Only ordered `Categoricals` have a minimum! + + Raises + ------ + TypeError + If the `Categorical` is not `ordered`. + + Returns + ------- + min : the minimum of this `Categorical`, NA value if empty + """ + nv.validate_minmax_axis(kwargs.get("axis", 0)) + nv.validate_min((), kwargs) + self.check_for_ordered("min") + + if not len(self._codes): + return self.dtype.na_value + + good = self._codes != -1 + if not good.all(): + if skipna and good.any(): + pointer = self._codes[good].min() + else: + return np.nan + else: + pointer = self._codes.min() + return self._wrap_reduction_result(None, pointer) + + def max(self, *, skipna: bool = True, **kwargs): + """ + The maximum value of the object. + + Only ordered `Categoricals` have a maximum! + + Raises + ------ + TypeError + If the `Categorical` is not `ordered`. + + Returns + ------- + max : the maximum of this `Categorical`, NA if array is empty + """ + nv.validate_minmax_axis(kwargs.get("axis", 0)) + nv.validate_max((), kwargs) + self.check_for_ordered("max") + + if not len(self._codes): + return self.dtype.na_value + + good = self._codes != -1 + if not good.all(): + if skipna and good.any(): + pointer = self._codes[good].max() + else: + return np.nan + else: + pointer = self._codes.max() + return self._wrap_reduction_result(None, pointer) + + def _mode(self, dropna: bool = True) -> Categorical: + codes = self._codes + mask = None + if dropna: + mask = self.isna() + + res_codes = algorithms.mode(codes, mask=mask) + res_codes = cast(np.ndarray, res_codes) + assert res_codes.dtype == codes.dtype + res = self._from_backing_data(res_codes) + return res + + # ------------------------------------------------------------------ + # ExtensionArray Interface + + def unique(self) -> Self: + """ + Return the ``Categorical`` which ``categories`` and ``codes`` are + unique. + + .. versionchanged:: 1.3.0 + + Previously, unused categories were dropped from the new categories. + + Returns + ------- + Categorical + + See Also + -------- + pandas.unique + CategoricalIndex.unique + Series.unique : Return unique values of Series object. + + Examples + -------- + >>> pd.Categorical(list("baabc")).unique() + ['b', 'a', 'c'] + Categories (3, object): ['a', 'b', 'c'] + >>> pd.Categorical(list("baab"), categories=list("abc"), ordered=True).unique() + ['b', 'a'] + Categories (3, object): ['a' < 'b' < 'c'] + """ + # pylint: disable=useless-parent-delegation + return super().unique() + + def _cast_quantile_result(self, res_values: np.ndarray) -> np.ndarray: + # make sure we have correct itemsize for resulting codes + assert res_values.dtype == self._ndarray.dtype + return res_values + + def equals(self, other: object) -> bool: + """ + Returns True if categorical arrays are equal. + + Parameters + ---------- + other : `Categorical` + + Returns + ------- + bool + """ + if not isinstance(other, Categorical): + return False + elif self._categories_match_up_to_permutation(other): + other = self._encode_with_my_categories(other) + return np.array_equal(self._codes, other._codes) + return False + + @classmethod + def _concat_same_type(cls, to_concat: Sequence[Self], axis: AxisInt = 0) -> Self: + from pandas.core.dtypes.concat import union_categoricals + + first = to_concat[0] + if axis >= first.ndim: + raise ValueError( + f"axis {axis} is out of bounds for array of dimension {first.ndim}" + ) + + if axis == 1: + # Flatten, concatenate then reshape + if not all(x.ndim == 2 for x in to_concat): + raise ValueError + + # pass correctly-shaped to union_categoricals + tc_flat = [] + for obj in to_concat: + tc_flat.extend([obj[:, i] for i in range(obj.shape[1])]) + + res_flat = cls._concat_same_type(tc_flat, axis=0) + + result = res_flat.reshape(len(first), -1, order="F") + return result + + result = union_categoricals(to_concat) + return result + + # ------------------------------------------------------------------ + + def _encode_with_my_categories(self, other: Categorical) -> Categorical: + """ + Re-encode another categorical using this Categorical's categories. + + Notes + ----- + This assumes we have already checked + self._categories_match_up_to_permutation(other). + """ + # Indexing on codes is more efficient if categories are the same, + # so we can apply some optimizations based on the degree of + # dtype-matching. + codes = recode_for_categories( + other.codes, other.categories, self.categories, copy=False + ) + return self._from_backing_data(codes) + + def _categories_match_up_to_permutation(self, other: Categorical) -> bool: + """ + Returns True if categoricals are the same dtype + same categories, and same ordered + + Parameters + ---------- + other : Categorical + + Returns + ------- + bool + """ + return hash(self.dtype) == hash(other.dtype) + + def describe(self) -> DataFrame: + """ + Describes this Categorical + + Returns + ------- + description: `DataFrame` + A dataframe with frequency and counts by category. + """ + counts = self.value_counts(dropna=False) + freqs = counts / counts.sum() + + from pandas import Index + from pandas.core.reshape.concat import concat + + result = concat([counts, freqs], axis=1) + result.columns = Index(["counts", "freqs"]) + result.index.name = "categories" + + return result + + def isin(self, values: ArrayLike) -> npt.NDArray[np.bool_]: + """ + Check whether `values` are contained in Categorical. + + Return a boolean NumPy Array showing whether each element in + the Categorical matches an element in the passed sequence of + `values` exactly. + + Parameters + ---------- + values : np.ndarray or ExtensionArray + The sequence of values to test. Passing in a single string will + raise a ``TypeError``. Instead, turn a single string into a + list of one element. + + Returns + ------- + np.ndarray[bool] + + Raises + ------ + TypeError + * If `values` is not a set or list-like + + See Also + -------- + pandas.Series.isin : Equivalent method on Series. + + Examples + -------- + >>> s = pd.Categorical(['lama', 'cow', 'lama', 'beetle', 'lama', + ... 'hippo']) + >>> s.isin(['cow', 'lama']) + array([ True, True, True, False, True, False]) + + Passing a single string as ``s.isin('lama')`` will raise an error. Use + a list of one element instead: + + >>> s.isin(['lama']) + array([ True, False, True, False, True, False]) + """ + null_mask = np.asarray(isna(values)) + code_values = self.categories.get_indexer_for(values) + code_values = code_values[null_mask | (code_values >= 0)] + return algorithms.isin(self.codes, code_values) + + def _replace(self, *, to_replace, value, inplace: bool = False): + from pandas import Index + + orig_dtype = self.dtype + + inplace = validate_bool_kwarg(inplace, "inplace") + cat = self if inplace else self.copy() + + mask = isna(np.asarray(value)) + if mask.any(): + removals = np.asarray(to_replace)[mask] + removals = cat.categories[cat.categories.isin(removals)] + new_cat = cat.remove_categories(removals) + NDArrayBacked.__init__(cat, new_cat.codes, new_cat.dtype) + + ser = cat.categories.to_series() + ser = ser.replace(to_replace=to_replace, value=value) + + all_values = Index(ser) + + # GH51016: maintain order of existing categories + idxr = cat.categories.get_indexer_for(all_values) + locs = np.arange(len(ser)) + locs = np.where(idxr == -1, locs, idxr) + locs = locs.argsort() + + new_categories = ser.take(locs) + new_categories = new_categories.drop_duplicates(keep="first") + new_categories = Index(new_categories) + new_codes = recode_for_categories( + cat._codes, all_values, new_categories, copy=False + ) + new_dtype = CategoricalDtype(new_categories, ordered=self.dtype.ordered) + NDArrayBacked.__init__(cat, new_codes, new_dtype) + + if new_dtype != orig_dtype: + warnings.warn( + # GH#55147 + "The behavior of Series.replace (and DataFrame.replace) with " + "CategoricalDtype is deprecated. In a future version, replace " + "will only be used for cases that preserve the categories. " + "To change the categories, use ser.cat.rename_categories " + "instead.", + FutureWarning, + stacklevel=find_stack_level(), + ) + if not inplace: + return cat + + # ------------------------------------------------------------------------ + # String methods interface + def _str_map( + self, f, na_value=np.nan, dtype=np.dtype("object"), convert: bool = True + ): + # Optimization to apply the callable `f` to the categories once + # and rebuild the result by `take`ing from the result with the codes. + # Returns the same type as the object-dtype implementation though. + from pandas.core.arrays import NumpyExtensionArray + + categories = self.categories + codes = self.codes + result = NumpyExtensionArray(categories.to_numpy())._str_map(f, na_value, dtype) + return take_nd(result, codes, fill_value=na_value) + + def _str_get_dummies(self, sep: str = "|"): + # sep may not be in categories. Just bail on this. + from pandas.core.arrays import NumpyExtensionArray + + return NumpyExtensionArray(self.astype(str))._str_get_dummies(sep) + + # ------------------------------------------------------------------------ + # GroupBy Methods + + def _groupby_op( + self, + *, + how: str, + has_dropped_na: bool, + min_count: int, + ngroups: int, + ids: npt.NDArray[np.intp], + **kwargs, + ): + from pandas.core.groupby.ops import WrappedCythonOp + + kind = WrappedCythonOp.get_kind_from_how(how) + op = WrappedCythonOp(how=how, kind=kind, has_dropped_na=has_dropped_na) + + dtype = self.dtype + if how in ["sum", "prod", "cumsum", "cumprod", "skew"]: + raise TypeError(f"{dtype} type does not support {how} operations") + if how in ["min", "max", "rank", "idxmin", "idxmax"] and not dtype.ordered: + # raise TypeError instead of NotImplementedError to ensure we + # don't go down a group-by-group path, since in the empty-groups + # case that would fail to raise + raise TypeError(f"Cannot perform {how} with non-ordered Categorical") + if how not in [ + "rank", + "any", + "all", + "first", + "last", + "min", + "max", + "idxmin", + "idxmax", + ]: + if kind == "transform": + raise TypeError(f"{dtype} type does not support {how} operations") + raise TypeError(f"{dtype} dtype does not support aggregation '{how}'") + + result_mask = None + mask = self.isna() + if how == "rank": + assert self.ordered # checked earlier + npvalues = self._ndarray + elif how in ["first", "last", "min", "max", "idxmin", "idxmax"]: + npvalues = self._ndarray + result_mask = np.zeros(ngroups, dtype=bool) + else: + # any/all + npvalues = self.astype(bool) + + res_values = op._cython_op_ndim_compat( + npvalues, + min_count=min_count, + ngroups=ngroups, + comp_ids=ids, + mask=mask, + result_mask=result_mask, + **kwargs, + ) + + if how in op.cast_blocklist: + return res_values + elif how in ["first", "last", "min", "max"]: + res_values[result_mask == 1] = -1 + return self._from_backing_data(res_values) + + +# The Series.cat accessor + + +@delegate_names( + delegate=Categorical, accessors=["categories", "ordered"], typ="property" +) +@delegate_names( + delegate=Categorical, + accessors=[ + "rename_categories", + "reorder_categories", + "add_categories", + "remove_categories", + "remove_unused_categories", + "set_categories", + "as_ordered", + "as_unordered", + ], + typ="method", +) +class CategoricalAccessor(PandasDelegate, PandasObject, NoNewAttributesMixin): + """ + Accessor object for categorical properties of the Series values. + + Parameters + ---------- + data : Series or CategoricalIndex + + Examples + -------- + >>> s = pd.Series(list("abbccc")).astype("category") + >>> s + 0 a + 1 b + 2 b + 3 c + 4 c + 5 c + dtype: category + Categories (3, object): ['a', 'b', 'c'] + + >>> s.cat.categories + Index(['a', 'b', 'c'], dtype='object') + + >>> s.cat.rename_categories(list("cba")) + 0 c + 1 b + 2 b + 3 a + 4 a + 5 a + dtype: category + Categories (3, object): ['c', 'b', 'a'] + + >>> s.cat.reorder_categories(list("cba")) + 0 a + 1 b + 2 b + 3 c + 4 c + 5 c + dtype: category + Categories (3, object): ['c', 'b', 'a'] + + >>> s.cat.add_categories(["d", "e"]) + 0 a + 1 b + 2 b + 3 c + 4 c + 5 c + dtype: category + Categories (5, object): ['a', 'b', 'c', 'd', 'e'] + + >>> s.cat.remove_categories(["a", "c"]) + 0 NaN + 1 b + 2 b + 3 NaN + 4 NaN + 5 NaN + dtype: category + Categories (1, object): ['b'] + + >>> s1 = s.cat.add_categories(["d", "e"]) + >>> s1.cat.remove_unused_categories() + 0 a + 1 b + 2 b + 3 c + 4 c + 5 c + dtype: category + Categories (3, object): ['a', 'b', 'c'] + + >>> s.cat.set_categories(list("abcde")) + 0 a + 1 b + 2 b + 3 c + 4 c + 5 c + dtype: category + Categories (5, object): ['a', 'b', 'c', 'd', 'e'] + + >>> s.cat.as_ordered() + 0 a + 1 b + 2 b + 3 c + 4 c + 5 c + dtype: category + Categories (3, object): ['a' < 'b' < 'c'] + + >>> s.cat.as_unordered() + 0 a + 1 b + 2 b + 3 c + 4 c + 5 c + dtype: category + Categories (3, object): ['a', 'b', 'c'] + """ + + def __init__(self, data) -> None: + self._validate(data) + self._parent = data.values + self._index = data.index + self._name = data.name + self._freeze() + + @staticmethod + def _validate(data): + if not isinstance(data.dtype, CategoricalDtype): + raise AttributeError("Can only use .cat accessor with a 'category' dtype") + + def _delegate_property_get(self, name: str): + return getattr(self._parent, name) + + # error: Signature of "_delegate_property_set" incompatible with supertype + # "PandasDelegate" + def _delegate_property_set(self, name: str, new_values): # type: ignore[override] + return setattr(self._parent, name, new_values) + + @property + def codes(self) -> Series: + """ + Return Series of codes as well as the index. + + Examples + -------- + >>> raw_cate = pd.Categorical(["a", "b", "c", "a"], categories=["a", "b"]) + >>> ser = pd.Series(raw_cate) + >>> ser.cat.codes + 0 0 + 1 1 + 2 -1 + 3 0 + dtype: int8 + """ + from pandas import Series + + return Series(self._parent.codes, index=self._index) + + def _delegate_method(self, name: str, *args, **kwargs): + from pandas import Series + + method = getattr(self._parent, name) + res = method(*args, **kwargs) + if res is not None: + return Series(res, index=self._index, name=self._name) + + +# utility routines + + +def _get_codes_for_values( + values: Index | Series | ExtensionArray | np.ndarray, + categories: Index, +) -> np.ndarray: + """ + utility routine to turn values into codes given the specified categories + + If `values` is known to be a Categorical, use recode_for_categories instead. + """ + codes = categories.get_indexer_for(values) + return coerce_indexer_dtype(codes, categories) + + +def recode_for_categories( + codes: np.ndarray, old_categories, new_categories, copy: bool = True +) -> np.ndarray: + """ + Convert a set of codes for to a new set of categories + + Parameters + ---------- + codes : np.ndarray + old_categories, new_categories : Index + copy: bool, default True + Whether to copy if the codes are unchanged. + + Returns + ------- + new_codes : np.ndarray[np.int64] + + Examples + -------- + >>> old_cat = pd.Index(['b', 'a', 'c']) + >>> new_cat = pd.Index(['a', 'b']) + >>> codes = np.array([0, 1, 1, 2]) + >>> recode_for_categories(codes, old_cat, new_cat) + array([ 1, 0, 0, -1], dtype=int8) + """ + if len(old_categories) == 0: + # All null anyway, so just retain the nulls + if copy: + return codes.copy() + return codes + elif new_categories.equals(old_categories): + # Same categories, so no need to actually recode + if copy: + return codes.copy() + return codes + + indexer = coerce_indexer_dtype( + new_categories.get_indexer_for(old_categories), new_categories + ) + new_codes = take_nd(indexer, codes, fill_value=-1) + return new_codes + + +def factorize_from_iterable(values) -> tuple[np.ndarray, Index]: + """ + Factorize an input `values` into `categories` and `codes`. Preserves + categorical dtype in `categories`. + + Parameters + ---------- + values : list-like + + Returns + ------- + codes : ndarray + categories : Index + If `values` has a categorical dtype, then `categories` is + a CategoricalIndex keeping the categories and order of `values`. + """ + from pandas import CategoricalIndex + + if not is_list_like(values): + raise TypeError("Input must be list-like") + + categories: Index + + vdtype = getattr(values, "dtype", None) + if isinstance(vdtype, CategoricalDtype): + values = extract_array(values) + # The Categorical we want to build has the same categories + # as values but its codes are by def [0, ..., len(n_categories) - 1] + cat_codes = np.arange(len(values.categories), dtype=values.codes.dtype) + cat = Categorical.from_codes(cat_codes, dtype=values.dtype, validate=False) + + categories = CategoricalIndex(cat) + codes = values.codes + else: + # The value of ordered is irrelevant since we don't use cat as such, + # but only the resulting categories, the order of which is independent + # from ordered. Set ordered to False as default. See GH #15457 + cat = Categorical(values, ordered=False) + categories = cat.categories + codes = cat.codes + return codes, categories + + +def factorize_from_iterables(iterables) -> tuple[list[np.ndarray], list[Index]]: + """ + A higher-level wrapper over `factorize_from_iterable`. + + Parameters + ---------- + iterables : list-like of list-likes + + Returns + ------- + codes : list of ndarrays + categories : list of Indexes + + Notes + ----- + See `factorize_from_iterable` for more info. + """ + if len(iterables) == 0: + # For consistency, it should return two empty lists. + return [], [] + + codes, categories = zip(*(factorize_from_iterable(it) for it in iterables)) + return list(codes), list(categories)