""" An interface for extending pandas with custom arrays. .. warning:: This is an experimental API and subject to breaking changes without warning. """ from __future__ import annotations import operator from typing import ( TYPE_CHECKING, Any, Callable, ClassVar, Iterator, Literal, Sequence, TypeVar, cast, overload, ) import numpy as np from pandas._libs import lib from pandas._typing import ( ArrayLike, AstypeArg, AxisInt, Dtype, FillnaOptions, PositionalIndexer, ScalarIndexer, SequenceIndexer, Shape, SortKind, TakeIndexer, npt, ) from pandas.compat import set_function_name from pandas.compat.numpy import function as nv from pandas.errors import AbstractMethodError from pandas.util._decorators import ( Appender, Substitution, cache_readonly, ) from pandas.util._validators import ( validate_bool_kwarg, validate_fillna_kwargs, validate_insert_loc, ) from pandas.core.dtypes.cast import maybe_cast_to_extension_array from pandas.core.dtypes.common import ( is_datetime64_dtype, is_dtype_equal, is_list_like, is_scalar, is_timedelta64_dtype, pandas_dtype, ) from pandas.core.dtypes.dtypes import ExtensionDtype from pandas.core.dtypes.generic import ( ABCDataFrame, ABCIndex, ABCSeries, ) from pandas.core.dtypes.missing import isna from pandas.core import ( arraylike, missing, roperator, ) from pandas.core.algorithms import ( factorize_array, isin, mode, rank, unique, ) from pandas.core.array_algos.quantile import quantile_with_mask from pandas.core.sorting import ( nargminmax, nargsort, ) if TYPE_CHECKING: from pandas._typing import ( NumpySorter, NumpyValueArrayLike, ) _extension_array_shared_docs: dict[str, str] = {} ExtensionArrayT = TypeVar("ExtensionArrayT", bound="ExtensionArray") class ExtensionArray: """ Abstract base class for custom 1-D array types. pandas will recognize instances of this class as proper arrays with a custom type and will not attempt to coerce them to objects. They may be stored directly inside a :class:`DataFrame` or :class:`Series`. Attributes ---------- dtype nbytes ndim shape Methods ------- argsort astype copy dropna factorize fillna equals insert isin isna ravel repeat searchsorted shift take tolist unique view _accumulate _concat_same_type _formatter _from_factorized _from_sequence _from_sequence_of_strings _reduce _values_for_argsort _values_for_factorize Notes ----- The interface includes the following abstract methods that must be implemented by subclasses: * _from_sequence * _from_factorized * __getitem__ * __len__ * __eq__ * dtype * nbytes * isna * take * copy * _concat_same_type A default repr displaying the type, (truncated) data, length, and dtype is provided. It can be customized or replaced by by overriding: * __repr__ : A default repr for the ExtensionArray. * _formatter : Print scalars inside a Series or DataFrame. Some methods require casting the ExtensionArray to an ndarray of Python objects with ``self.astype(object)``, which may be expensive. When performance is a concern, we highly recommend overriding the following methods: * fillna * dropna * unique * factorize / _values_for_factorize * argsort, argmax, argmin / _values_for_argsort * searchsorted The remaining methods implemented on this class should be performant, as they only compose abstract methods. Still, a more efficient implementation may be available, and these methods can be overridden. One can implement methods to handle array accumulations or reductions. * _accumulate * _reduce One can implement methods to handle parsing from strings that will be used in methods such as ``pandas.io.parsers.read_csv``. * _from_sequence_of_strings This class does not inherit from 'abc.ABCMeta' for performance reasons. Methods and properties required by the interface raise ``pandas.errors.AbstractMethodError`` and no ``register`` method is provided for registering virtual subclasses. ExtensionArrays are limited to 1 dimension. They may be backed by none, one, or many NumPy arrays. For example, ``pandas.Categorical`` is an extension array backed by two arrays, one for codes and one for categories. An array of IPv6 address may be backed by a NumPy structured array with two fields, one for the lower 64 bits and one for the upper 64 bits. Or they may be backed by some other storage type, like Python lists. Pandas makes no assumptions on how the data are stored, just that it can be converted to a NumPy array. The ExtensionArray interface does not impose any rules on how this data is stored. However, currently, the backing data cannot be stored in attributes called ``.values`` or ``._values`` to ensure full compatibility with pandas internals. But other names as ``.data``, ``._data``, ``._items``, ... can be freely used. If implementing NumPy's ``__array_ufunc__`` interface, pandas expects that 1. You defer by returning ``NotImplemented`` when any Series are present in `inputs`. Pandas will extract the arrays and call the ufunc again. 2. You define a ``_HANDLED_TYPES`` tuple as an attribute on the class. Pandas inspect this to determine whether the ufunc is valid for the types present. See :ref:`extending.extension.ufunc` for more. By default, ExtensionArrays are not hashable. Immutable subclasses may override this behavior. """ # '_typ' is for pandas.core.dtypes.generic.ABCExtensionArray. # Don't override this. _typ = "extension" # ------------------------------------------------------------------------ # Constructors # ------------------------------------------------------------------------ @classmethod def _from_sequence(cls, scalars, *, dtype: Dtype | None = None, copy: bool = False): """ Construct a new ExtensionArray from a sequence of scalars. Parameters ---------- scalars : Sequence Each element will be an instance of the scalar type for this array, ``cls.dtype.type`` or be converted into this type in this method. dtype : dtype, optional Construct for this particular dtype. This should be a Dtype compatible with the ExtensionArray. copy : bool, default False If True, copy the underlying data. Returns ------- ExtensionArray """ raise AbstractMethodError(cls) @classmethod def _from_sequence_of_strings( cls, strings, *, dtype: Dtype | None = None, copy: bool = False ): """ Construct a new ExtensionArray from a sequence of strings. Parameters ---------- strings : Sequence Each element will be an instance of the scalar type for this array, ``cls.dtype.type``. dtype : dtype, optional Construct for this particular dtype. This should be a Dtype compatible with the ExtensionArray. copy : bool, default False If True, copy the underlying data. Returns ------- ExtensionArray """ raise AbstractMethodError(cls) @classmethod def _from_factorized(cls, values, original): """ Reconstruct an ExtensionArray after factorization. Parameters ---------- values : ndarray An integer ndarray with the factorized values. original : ExtensionArray The original ExtensionArray that factorize was called on. See Also -------- factorize : Top-level factorize method that dispatches here. ExtensionArray.factorize : Encode the extension array as an enumerated type. """ raise AbstractMethodError(cls) # ------------------------------------------------------------------------ # Must be a Sequence # ------------------------------------------------------------------------ @overload def __getitem__(self, item: ScalarIndexer) -> Any: ... @overload def __getitem__(self: ExtensionArrayT, item: SequenceIndexer) -> ExtensionArrayT: ... def __getitem__( self: ExtensionArrayT, item: PositionalIndexer ) -> ExtensionArrayT | Any: """ Select a subset of self. Parameters ---------- item : int, slice, or ndarray * int: The position in 'self' to get. * slice: A slice object, where 'start', 'stop', and 'step' are integers or None * ndarray: A 1-d boolean NumPy ndarray the same length as 'self' * list[int]: A list of int Returns ------- item : scalar or ExtensionArray Notes ----- For scalar ``item``, return a scalar value suitable for the array's type. This should be an instance of ``self.dtype.type``. For slice ``key``, return an instance of ``ExtensionArray``, even if the slice is length 0 or 1. For a boolean mask, return an instance of ``ExtensionArray``, filtered to the values where ``item`` is True. """ raise AbstractMethodError(self) def __setitem__(self, key, value) -> None: """ Set one or more values inplace. This method is not required to satisfy the pandas extension array interface. Parameters ---------- key : int, ndarray, or slice When called from, e.g. ``Series.__setitem__``, ``key`` will be one of * scalar int * ndarray of integers. * boolean ndarray * slice object value : ExtensionDtype.type, Sequence[ExtensionDtype.type], or object value or values to be set of ``key``. Returns ------- None """ # Some notes to the ExtensionArray implementor who may have ended up # here. While this method is not required for the interface, if you # *do* choose to implement __setitem__, then some semantics should be # observed: # # * Setting multiple values : ExtensionArrays should support setting # multiple values at once, 'key' will be a sequence of integers and # 'value' will be a same-length sequence. # # * Broadcasting : For a sequence 'key' and a scalar 'value', # each position in 'key' should be set to 'value'. # # * Coercion : Most users will expect basic coercion to work. For # example, a string like '2018-01-01' is coerced to a datetime # when setting on a datetime64ns array. In general, if the # __init__ method coerces that value, then so should __setitem__ # Note, also, that Series/DataFrame.where internally use __setitem__ # on a copy of the data. raise NotImplementedError(f"{type(self)} does not implement __setitem__.") def __len__(self) -> int: """ Length of this array Returns ------- length : int """ raise AbstractMethodError(self) def __iter__(self) -> Iterator[Any]: """ Iterate over elements of the array. """ # This needs to be implemented so that pandas recognizes extension # arrays as list-like. The default implementation makes successive # calls to ``__getitem__``, which may be slower than necessary. for i in range(len(self)): yield self[i] def __contains__(self, item: object) -> bool | np.bool_: """ Return for `item in self`. """ # GH37867 # comparisons of any item to pd.NA always return pd.NA, so e.g. "a" in [pd.NA] # would raise a TypeError. The implementation below works around that. if is_scalar(item) and isna(item): if not self._can_hold_na: return False elif item is self.dtype.na_value or isinstance(item, self.dtype.type): return self._hasna else: return False else: # error: Item "ExtensionArray" of "Union[ExtensionArray, ndarray]" has no # attribute "any" return (item == self).any() # type: ignore[union-attr] # error: Signature of "__eq__" incompatible with supertype "object" def __eq__(self, other: Any) -> ArrayLike: # type: ignore[override] """ Return for `self == other` (element-wise equality). """ # Implementer note: this should return a boolean numpy ndarray or # a boolean ExtensionArray. # When `other` is one of Series, Index, or DataFrame, this method should # return NotImplemented (to ensure that those objects are responsible for # first unpacking the arrays, and then dispatch the operation to the # underlying arrays) raise AbstractMethodError(self) # error: Signature of "__ne__" incompatible with supertype "object" def __ne__(self, other: Any) -> ArrayLike: # type: ignore[override] """ Return for `self != other` (element-wise in-equality). """ return ~(self == other) def to_numpy( self, dtype: npt.DTypeLike | None = None, copy: bool = False, na_value: object = lib.no_default, ) -> np.ndarray: """ Convert to a NumPy ndarray. This is similar to :meth:`numpy.asarray`, but may provide additional control over how the conversion is done. Parameters ---------- dtype : str or numpy.dtype, optional The dtype to pass to :meth:`numpy.asarray`. copy : bool, default False Whether to ensure that the returned value is a not a view on another array. Note that ``copy=False`` does not *ensure* that ``to_numpy()`` is no-copy. Rather, ``copy=True`` ensure that a copy is made, even if not strictly necessary. na_value : Any, optional The value to use for missing values. The default value depends on `dtype` and the type of the array. Returns ------- numpy.ndarray """ result = np.asarray(self, dtype=dtype) if copy or na_value is not lib.no_default: result = result.copy() if na_value is not lib.no_default: result[self.isna()] = na_value return result # ------------------------------------------------------------------------ # Required attributes # ------------------------------------------------------------------------ @property def dtype(self) -> ExtensionDtype: """ An instance of 'ExtensionDtype'. """ raise AbstractMethodError(self) @property def shape(self) -> Shape: """ Return a tuple of the array dimensions. """ return (len(self),) @property def size(self) -> int: """ The number of elements in the array. """ # error: Incompatible return value type (got "signedinteger[_64Bit]", # expected "int") [return-value] return np.prod(self.shape) # type: ignore[return-value] @property def ndim(self) -> int: """ Extension Arrays are only allowed to be 1-dimensional. """ return 1 @property def nbytes(self) -> int: """ The number of bytes needed to store this object in memory. """ # If this is expensive to compute, return an approximate lower bound # on the number of bytes needed. raise AbstractMethodError(self) # ------------------------------------------------------------------------ # Additional Methods # ------------------------------------------------------------------------ @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: """ Cast to a NumPy array or ExtensionArray with 'dtype'. Parameters ---------- dtype : str or dtype Typecode or data-type to which the array is cast. copy : bool, default True Whether to copy the data, even if not necessary. If False, a copy is made only if the old dtype does not match the new dtype. Returns ------- np.ndarray or pandas.api.extensions.ExtensionArray An ExtensionArray if dtype is ExtensionDtype, Otherwise a NumPy ndarray with 'dtype' for its dtype. """ dtype = pandas_dtype(dtype) if is_dtype_equal(dtype, self.dtype): if not copy: return self else: return self.copy() if isinstance(dtype, ExtensionDtype): cls = dtype.construct_array_type() return cls._from_sequence(self, dtype=dtype, copy=copy) elif is_datetime64_dtype(dtype): from pandas.core.arrays import DatetimeArray return DatetimeArray._from_sequence(self, dtype=dtype, copy=copy) elif is_timedelta64_dtype(dtype): from pandas.core.arrays import TimedeltaArray return TimedeltaArray._from_sequence(self, dtype=dtype, copy=copy) return np.array(self, dtype=dtype, copy=copy) def isna(self) -> np.ndarray | ExtensionArraySupportsAnyAll: """ A 1-D array indicating if each value is missing. Returns ------- numpy.ndarray or pandas.api.extensions.ExtensionArray In most cases, this should return a NumPy ndarray. For exceptional cases like ``SparseArray``, where returning an ndarray would be expensive, an ExtensionArray may be returned. Notes ----- If returning an ExtensionArray, then * ``na_values._is_boolean`` should be True * `na_values` should implement :func:`ExtensionArray._reduce` * ``na_values.any`` and ``na_values.all`` should be implemented """ raise AbstractMethodError(self) @property def _hasna(self) -> bool: # GH#22680 """ Equivalent to `self.isna().any()`. Some ExtensionArray subclasses may be able to optimize this check. """ return bool(self.isna().any()) def _values_for_argsort(self) -> np.ndarray: """ Return values for sorting. Returns ------- ndarray The transformed values should maintain the ordering between values within the array. See Also -------- ExtensionArray.argsort : Return the indices that would sort this array. Notes ----- The caller is responsible for *not* modifying these values in-place, so it is safe for implementors to give views on `self`. Functions that use this (e.g. ExtensionArray.argsort) should ignore entries with missing values in the original array (according to `self.isna()`). This means that the corresponding entries in the returned array don't need to be modified to sort correctly. """ # Note: this is used in `ExtensionArray.argsort/argmin/argmax`. return np.array(self) def argsort( self, *, ascending: bool = True, kind: SortKind = "quicksort", na_position: str = "last", **kwargs, ) -> np.ndarray: """ Return the indices that would sort this array. Parameters ---------- ascending : bool, default True Whether the indices should result in an ascending or descending sort. kind : {'quicksort', 'mergesort', 'heapsort', 'stable'}, optional Sorting algorithm. *args, **kwargs: Passed through to :func:`numpy.argsort`. Returns ------- np.ndarray[np.intp] Array of indices that sort ``self``. If NaN values are contained, NaN values are placed at the end. See Also -------- numpy.argsort : Sorting implementation used internally. """ # Implementor note: You have two places to override the behavior of # argsort. # 1. _values_for_argsort : construct the values passed to np.argsort # 2. argsort : total control over sorting. In case of overriding this, # it is recommended to also override argmax/argmin ascending = nv.validate_argsort_with_ascending(ascending, (), kwargs) values = self._values_for_argsort() return nargsort( values, kind=kind, ascending=ascending, na_position=na_position, mask=np.asarray(self.isna()), ) def argmin(self, skipna: bool = True) -> int: """ Return the index of minimum value. In case of multiple occurrences of the minimum value, the index corresponding to the first occurrence is returned. Parameters ---------- skipna : bool, default True Returns ------- int See Also -------- ExtensionArray.argmax """ # Implementor note: You have two places to override the behavior of # argmin. # 1. _values_for_argsort : construct the values used in nargminmax # 2. argmin itself : total control over sorting. validate_bool_kwarg(skipna, "skipna") if not skipna and self._hasna: raise NotImplementedError return nargminmax(self, "argmin") def argmax(self, skipna: bool = True) -> int: """ Return the index of maximum value. In case of multiple occurrences of the maximum value, the index corresponding to the first occurrence is returned. Parameters ---------- skipna : bool, default True Returns ------- int See Also -------- ExtensionArray.argmin """ # Implementor note: You have two places to override the behavior of # argmax. # 1. _values_for_argsort : construct the values used in nargminmax # 2. argmax itself : total control over sorting. validate_bool_kwarg(skipna, "skipna") if not skipna and self._hasna: raise NotImplementedError return nargminmax(self, "argmax") def fillna( self: ExtensionArrayT, value: object | ArrayLike | None = None, method: FillnaOptions | None = None, limit: int | None = None, ) -> ExtensionArrayT: """ Fill NA/NaN values using the specified method. Parameters ---------- value : scalar, array-like If a scalar value is passed it is used to fill all missing values. Alternatively, an array-like 'value' can be given. It's expected that the array-like have the same length as 'self'. method : {'backfill', 'bfill', 'pad', 'ffill', None}, default None Method to use for filling holes in reindexed Series: * pad / ffill: propagate last valid observation forward to next valid. * backfill / bfill: use NEXT valid observation to fill gap. limit : int, default None If method is specified, this is the maximum number of consecutive NaN values to forward/backward fill. In other words, if there is a gap with more than this number of consecutive NaNs, it will only be partially filled. If method is not specified, this is the maximum number of entries along the entire axis where NaNs will be filled. Returns ------- ExtensionArray With NA/NaN filled. """ value, method = validate_fillna_kwargs(value, method) mask = self.isna() # error: Argument 2 to "check_value_size" has incompatible type # "ExtensionArray"; expected "ndarray" value = missing.check_value_size( value, mask, len(self) # type: ignore[arg-type] ) if mask.any(): if method is not None: func = missing.get_fill_func(method) npvalues = self.astype(object) func(npvalues, limit=limit, mask=mask) new_values = self._from_sequence(npvalues, dtype=self.dtype) else: # fill with value new_values = self.copy() new_values[mask] = value else: new_values = self.copy() return new_values def dropna(self: ExtensionArrayT) -> ExtensionArrayT: """ Return ExtensionArray without NA values. Returns ------- pandas.api.extensions.ExtensionArray """ # error: Unsupported operand type for ~ ("ExtensionArray") return self[~self.isna()] # type: ignore[operator] def shift(self, periods: int = 1, fill_value: object = None) -> ExtensionArray: """ Shift values by desired number. Newly introduced missing values are filled with ``self.dtype.na_value``. Parameters ---------- periods : int, default 1 The number of periods to shift. Negative values are allowed for shifting backwards. fill_value : object, optional The scalar value to use for newly introduced missing values. The default is ``self.dtype.na_value``. Returns ------- ExtensionArray Shifted. Notes ----- If ``self`` is empty or ``periods`` is 0, a copy of ``self`` is returned. If ``periods > len(self)``, then an array of size len(self) is returned, with all values filled with ``self.dtype.na_value``. """ # Note: this implementation assumes that `self.dtype.na_value` can be # stored in an instance of your ExtensionArray with `self.dtype`. if not len(self) or periods == 0: return self.copy() if isna(fill_value): fill_value = self.dtype.na_value empty = self._from_sequence( [fill_value] * min(abs(periods), len(self)), dtype=self.dtype ) if periods > 0: a = empty b = self[:-periods] else: a = self[abs(periods) :] b = empty return self._concat_same_type([a, b]) def unique(self: ExtensionArrayT) -> ExtensionArrayT: """ Compute the ExtensionArray of unique values. Returns ------- pandas.api.extensions.ExtensionArray """ uniques = unique(self.astype(object)) return self._from_sequence(uniques, dtype=self.dtype) def searchsorted( self, value: NumpyValueArrayLike | ExtensionArray, side: Literal["left", "right"] = "left", sorter: NumpySorter = None, ) -> npt.NDArray[np.intp] | np.intp: """ Find indices where elements should be inserted to maintain order. Find the indices into a sorted array `self` (a) such that, if the corresponding elements in `value` were inserted before the indices, the order of `self` would be preserved. Assuming that `self` is sorted: ====== ================================ `side` returned index `i` satisfies ====== ================================ left ``self[i-1] < value <= self[i]`` right ``self[i-1] <= value < self[i]`` ====== ================================ Parameters ---------- value : array-like, list or scalar Value(s) to insert into `self`. side : {'left', 'right'}, optional If 'left', the index of the first suitable location found is given. If 'right', return the last such index. If there is no suitable index, return either 0 or N (where N is the length of `self`). sorter : 1-D array-like, optional Optional array of integer indices that sort array a into ascending order. They are typically the result of argsort. Returns ------- array of ints or int If value is array-like, array of insertion points. If value is scalar, a single integer. See Also -------- numpy.searchsorted : Similar method from NumPy. """ # Note: the base tests provided by pandas only test the basics. # We do not test # 1. Values outside the range of the `data_for_sorting` fixture # 2. Values between the values in the `data_for_sorting` fixture # 3. Missing values. arr = self.astype(object) if isinstance(value, ExtensionArray): value = value.astype(object) return arr.searchsorted(value, side=side, sorter=sorter) def equals(self, other: object) -> bool: """ Return if another array is equivalent to this array. Equivalent means that both arrays have the same shape and dtype, and all values compare equal. Missing values in the same location are considered equal (in contrast with normal equality). Parameters ---------- other : ExtensionArray Array to compare to this Array. Returns ------- boolean Whether the arrays are equivalent. """ if type(self) != type(other): return False other = cast(ExtensionArray, other) if not is_dtype_equal(self.dtype, other.dtype): return False elif len(self) != len(other): return False else: equal_values = self == other if isinstance(equal_values, ExtensionArray): # boolean array with NA -> fill with False equal_values = equal_values.fillna(False) # error: Unsupported left operand type for & ("ExtensionArray") equal_na = self.isna() & other.isna() # type: ignore[operator] return bool((equal_values | equal_na).all()) def isin(self, values) -> npt.NDArray[np.bool_]: """ Pointwise comparison for set containment in the given values. Roughly equivalent to `np.array([x in values for x in self])` Parameters ---------- values : Sequence Returns ------- np.ndarray[bool] """ return isin(np.asarray(self), values) def _values_for_factorize(self) -> tuple[np.ndarray, Any]: """ Return an array and missing value suitable for factorization. Returns ------- values : ndarray An array suitable for factorization. This should maintain order and be a supported dtype (Float64, Int64, UInt64, String, Object). By default, the extension array is cast to object dtype. na_value : object The value in `values` to consider missing. This will be treated as NA in the factorization routines, so it will be coded as `-1` and not included in `uniques`. By default, ``np.nan`` is used. Notes ----- The values returned by this method are also used in :func:`pandas.util.hash_pandas_object`. """ return self.astype(object), np.nan def factorize( self, use_na_sentinel: bool = True, ) -> tuple[np.ndarray, ExtensionArray]: """ Encode the extension array as an enumerated type. Parameters ---------- use_na_sentinel : bool, default True If True, the sentinel -1 will be used for NaN values. If False, NaN values will be encoded as non-negative integers and will not drop the NaN from the uniques of the values. .. versionadded:: 1.5.0 Returns ------- codes : ndarray An integer NumPy array that's an indexer into the original ExtensionArray. uniques : ExtensionArray An ExtensionArray containing the unique values of `self`. .. note:: uniques will *not* contain an entry for the NA value of the ExtensionArray if there are any missing values present in `self`. See Also -------- factorize : Top-level factorize method that dispatches here. Notes ----- :meth:`pandas.factorize` offers a `sort` keyword as well. """ # Implementer note: There are two ways to override the behavior of # pandas.factorize # 1. _values_for_factorize and _from_factorize. # Specify the values passed to pandas' internal factorization # routines, and how to convert from those values back to the # original ExtensionArray. # 2. ExtensionArray.factorize. # Complete control over factorization. arr, na_value = self._values_for_factorize() codes, uniques = factorize_array( arr, use_na_sentinel=use_na_sentinel, na_value=na_value ) uniques_ea = self._from_factorized(uniques, self) return codes, uniques_ea _extension_array_shared_docs[ "repeat" ] = """ Repeat elements of a %(klass)s. Returns a new %(klass)s where each element of the current %(klass)s is repeated consecutively a given number of times. Parameters ---------- repeats : int or array of ints The number of repetitions for each element. This should be a non-negative integer. Repeating 0 times will return an empty %(klass)s. axis : None Must be ``None``. Has no effect but is accepted for compatibility with numpy. Returns ------- %(klass)s Newly created %(klass)s with repeated elements. See Also -------- Series.repeat : Equivalent function for Series. Index.repeat : Equivalent function for Index. numpy.repeat : Similar method for :class:`numpy.ndarray`. ExtensionArray.take : Take arbitrary positions. Examples -------- >>> cat = pd.Categorical(['a', 'b', 'c']) >>> cat ['a', 'b', 'c'] Categories (3, object): ['a', 'b', 'c'] >>> cat.repeat(2) ['a', 'a', 'b', 'b', 'c', 'c'] Categories (3, object): ['a', 'b', 'c'] >>> cat.repeat([1, 2, 3]) ['a', 'b', 'b', 'c', 'c', 'c'] Categories (3, object): ['a', 'b', 'c'] """ @Substitution(klass="ExtensionArray") @Appender(_extension_array_shared_docs["repeat"]) def repeat( self: ExtensionArrayT, repeats: int | Sequence[int], axis: AxisInt | None = None ) -> ExtensionArrayT: nv.validate_repeat((), {"axis": axis}) ind = np.arange(len(self)).repeat(repeats) return self.take(ind) # ------------------------------------------------------------------------ # Indexing methods # ------------------------------------------------------------------------ def take( self: ExtensionArrayT, indices: TakeIndexer, *, allow_fill: bool = False, fill_value: Any = None, ) -> ExtensionArrayT: """ Take elements from an array. Parameters ---------- indices : sequence of int or one-dimensional np.ndarray of int Indices to be taken. allow_fill : bool, default False How to handle negative values in `indices`. * False: negative values in `indices` indicate positional indices from the right (the default). This is similar to :func:`numpy.take`. * True: negative values in `indices` indicate missing values. These values are set to `fill_value`. Any other other negative values raise a ``ValueError``. fill_value : any, optional Fill value to use for NA-indices when `allow_fill` is True. This may be ``None``, in which case the default NA value for the type, ``self.dtype.na_value``, is used. For many ExtensionArrays, there will be two representations of `fill_value`: a user-facing "boxed" scalar, and a low-level physical NA value. `fill_value` should be the user-facing version, and the implementation should handle translating that to the physical version for processing the take if necessary. Returns ------- ExtensionArray Raises ------ IndexError When the indices are out of bounds for the array. ValueError When `indices` contains negative values other than ``-1`` and `allow_fill` is True. See Also -------- numpy.take : Take elements from an array along an axis. api.extensions.take : Take elements from an array. Notes ----- ExtensionArray.take is called by ``Series.__getitem__``, ``.loc``, ``iloc``, when `indices` is a sequence of values. Additionally, it's called by :meth:`Series.reindex`, or any other method that causes realignment, with a `fill_value`. Examples -------- Here's an example implementation, which relies on casting the extension array to object dtype. This uses the helper method :func:`pandas.api.extensions.take`. .. code-block:: python def take(self, indices, allow_fill=False, fill_value=None): from pandas.core.algorithms import take # If the ExtensionArray is backed by an ndarray, then # just pass that here instead of coercing to object. data = self.astype(object) if allow_fill and fill_value is None: fill_value = self.dtype.na_value # fill value should always be translated from the scalar # type for the array, to the physical storage type for # the data, before passing to take. result = take(data, indices, fill_value=fill_value, allow_fill=allow_fill) return self._from_sequence(result, dtype=self.dtype) """ # Implementer note: The `fill_value` parameter should be a user-facing # value, an instance of self.dtype.type. When passed `fill_value=None`, # the default of `self.dtype.na_value` should be used. # This may differ from the physical storage type your ExtensionArray # uses. In this case, your implementation is responsible for casting # the user-facing type to the storage type, before using # pandas.api.extensions.take raise AbstractMethodError(self) def copy(self: ExtensionArrayT) -> ExtensionArrayT: """ Return a copy of the array. Returns ------- ExtensionArray """ raise AbstractMethodError(self) def view(self, dtype: Dtype | None = None) -> ArrayLike: """ Return a view on the array. Parameters ---------- dtype : str, np.dtype, or ExtensionDtype, optional Default None. Returns ------- ExtensionArray or np.ndarray A view on the :class:`ExtensionArray`'s data. """ # NB: # - This must return a *new* object referencing the same data, not self. # - The only case that *must* be implemented is with dtype=None, # giving a view with the same dtype as self. if dtype is not None: raise NotImplementedError(dtype) return self[:] # ------------------------------------------------------------------------ # Printing # ------------------------------------------------------------------------ def __repr__(self) -> str: if self.ndim > 1: return self._repr_2d() from pandas.io.formats.printing import format_object_summary # the short repr has no trailing newline, while the truncated # repr does. So we include a newline in our template, and strip # any trailing newlines from format_object_summary data = format_object_summary( self, self._formatter(), indent_for_name=False ).rstrip(", \n") class_name = f"<{type(self).__name__}>\n" return f"{class_name}{data}\nLength: {len(self)}, dtype: {self.dtype}" def _repr_2d(self) -> str: from pandas.io.formats.printing import format_object_summary # the short repr has no trailing newline, while the truncated # repr does. So we include a newline in our template, and strip # any trailing newlines from format_object_summary lines = [ format_object_summary(x, self._formatter(), indent_for_name=False).rstrip( ", \n" ) for x in self ] data = ",\n".join(lines) class_name = f"<{type(self).__name__}>" return f"{class_name}\n[\n{data}\n]\nShape: {self.shape}, dtype: {self.dtype}" def _formatter(self, boxed: bool = False) -> Callable[[Any], str | None]: """ Formatting function for scalar values. This is used in the default '__repr__'. The returned formatting function receives instances of your scalar type. Parameters ---------- boxed : bool, default False An indicated for whether or not your array is being printed within a Series, DataFrame, or Index (True), or just by itself (False). This may be useful if you want scalar values to appear differently within a Series versus on its own (e.g. quoted or not). Returns ------- Callable[[Any], str] A callable that gets instances of the scalar type and returns a string. By default, :func:`repr` is used when ``boxed=False`` and :func:`str` is used when ``boxed=True``. """ if boxed: return str return repr # ------------------------------------------------------------------------ # Reshaping # ------------------------------------------------------------------------ def transpose(self, *axes: int) -> ExtensionArray: """ Return a transposed view on this array. Because ExtensionArrays are always 1D, this is a no-op. It is included for compatibility with np.ndarray. """ return self[:] @property def T(self) -> ExtensionArray: return self.transpose() def ravel(self, order: Literal["C", "F", "A", "K"] | None = "C") -> ExtensionArray: """ Return a flattened view on this array. Parameters ---------- order : {None, 'C', 'F', 'A', 'K'}, default 'C' Returns ------- ExtensionArray Notes ----- - Because ExtensionArrays are 1D-only, this is a no-op. - The "order" argument is ignored, is for compatibility with NumPy. """ return self @classmethod def _concat_same_type( cls: type[ExtensionArrayT], to_concat: Sequence[ExtensionArrayT] ) -> ExtensionArrayT: """ Concatenate multiple array of this dtype. Parameters ---------- to_concat : sequence of this type Returns ------- ExtensionArray """ # Implementer note: this method will only be called with a sequence of # ExtensionArrays of this class and with the same dtype as self. This # should allow "easy" concatenation (no upcasting needed), and result # in a new ExtensionArray of the same dtype. # Note: this strict behaviour is only guaranteed starting with pandas 1.1 raise AbstractMethodError(cls) # The _can_hold_na attribute is set to True so that pandas internals # will use the ExtensionDtype.na_value as the NA value in operations # such as take(), reindex(), shift(), etc. In addition, those results # will then be of the ExtensionArray subclass rather than an array # of objects @cache_readonly def _can_hold_na(self) -> bool: return self.dtype._can_hold_na def _accumulate( self, name: str, *, skipna: bool = True, **kwargs ) -> ExtensionArray: """ Return an ExtensionArray performing an accumulation operation. The underlying data type might change. Parameters ---------- name : str Name of the function, supported values are: - cummin - cummax - cumsum - cumprod skipna : bool, default True If True, skip NA values. **kwargs Additional keyword arguments passed to the accumulation function. Currently, there is no supported kwarg. Returns ------- array Raises ------ NotImplementedError : subclass does not define accumulations """ raise NotImplementedError(f"cannot perform {name} with type {self.dtype}") def _reduce(self, name: str, *, skipna: bool = True, **kwargs): """ Return a scalar result of performing the reduction operation. Parameters ---------- name : str Name of the function, supported values are: { any, all, min, max, sum, mean, median, prod, std, var, sem, kurt, skew }. skipna : bool, default True If True, skip NaN values. **kwargs Additional keyword arguments passed to the reduction function. Currently, `ddof` is the only supported kwarg. Returns ------- scalar Raises ------ TypeError : subclass does not define reductions """ meth = getattr(self, name, None) if meth is None: raise TypeError( f"'{type(self).__name__}' with dtype {self.dtype} " f"does not support reduction '{name}'" ) return meth(skipna=skipna, **kwargs) # https://github.com/python/typeshed/issues/2148#issuecomment-520783318 # Incompatible types in assignment (expression has type "None", base class # "object" defined the type as "Callable[[object], int]") __hash__: ClassVar[None] # type: ignore[assignment] # ------------------------------------------------------------------------ # Non-Optimized Default Methods; in the case of the private methods here, # these are not guaranteed to be stable across pandas versions. def tolist(self) -> list: """ Return a list of the values. These are each a scalar type, which is a Python scalar (for str, int, float) or a pandas scalar (for Timestamp/Timedelta/Interval/Period) Returns ------- list """ if self.ndim > 1: return [x.tolist() for x in self] return list(self) def delete(self: ExtensionArrayT, loc: PositionalIndexer) -> ExtensionArrayT: indexer = np.delete(np.arange(len(self)), loc) return self.take(indexer) def insert(self: ExtensionArrayT, loc: int, item) -> ExtensionArrayT: """ Insert an item at the given position. Parameters ---------- loc : int item : scalar-like Returns ------- same type as self Notes ----- This method should be both type and dtype-preserving. If the item cannot be held in an array of this type/dtype, either ValueError or TypeError should be raised. The default implementation relies on _from_sequence to raise on invalid items. """ loc = validate_insert_loc(loc, len(self)) item_arr = type(self)._from_sequence([item], dtype=self.dtype) return type(self)._concat_same_type([self[:loc], item_arr, self[loc:]]) def _putmask(self, mask: npt.NDArray[np.bool_], value) -> None: """ Analogue to np.putmask(self, mask, value) Parameters ---------- mask : np.ndarray[bool] value : scalar or listlike If listlike, must be arraylike with same length as self. Returns ------- None Notes ----- Unlike np.putmask, we do not repeat listlike values with mismatched length. 'value' should either be a scalar or an arraylike with the same length as self. """ if is_list_like(value): val = value[mask] else: val = value self[mask] = val def _where( self: ExtensionArrayT, mask: npt.NDArray[np.bool_], value ) -> ExtensionArrayT: """ Analogue to np.where(mask, self, value) Parameters ---------- mask : np.ndarray[bool] value : scalar or listlike Returns ------- same type as self """ result = self.copy() if is_list_like(value): val = value[~mask] else: val = value result[~mask] = val return result def _fill_mask_inplace( self, method: str, limit, mask: npt.NDArray[np.bool_] ) -> None: """ Replace values in locations specified by 'mask' using pad or backfill. See also -------- ExtensionArray.fillna """ func = missing.get_fill_func(method) npvalues = self.astype(object) # NB: if we don't copy mask here, it may be altered inplace, which # would mess up the `self[mask] = ...` below. func(npvalues, limit=limit, mask=mask.copy()) new_values = self._from_sequence(npvalues, dtype=self.dtype) self[mask] = new_values[mask] 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 return rank( self, axis=axis, method=method, na_option=na_option, ascending=ascending, pct=pct, ) @classmethod def _empty(cls, shape: Shape, dtype: ExtensionDtype): """ Create an ExtensionArray with the given shape and dtype. See also -------- ExtensionDtype.empty ExtensionDtype.empty is the 'official' public version of this API. """ # Implementer note: while ExtensionDtype.empty is the public way to # call this method, it is still required to implement this `_empty` # method as well (it is called internally in pandas) obj = cls._from_sequence([], dtype=dtype) taker = np.broadcast_to(np.intp(-1), shape) result = obj.take(taker, allow_fill=True) if not isinstance(result, cls) or dtype != result.dtype: raise NotImplementedError( f"Default 'empty' implementation is invalid for dtype='{dtype}'" ) return result def _quantile( self: ExtensionArrayT, qs: npt.NDArray[np.float64], interpolation: str ) -> ExtensionArrayT: """ Compute the quantiles of self for each quantile in `qs`. Parameters ---------- qs : np.ndarray[float64] interpolation: str Returns ------- same type as self """ mask = np.asarray(self.isna()) arr = np.asarray(self) fill_value = np.nan res_values = quantile_with_mask(arr, mask, fill_value, qs, interpolation) return type(self)._from_sequence(res_values) def _mode(self: ExtensionArrayT, dropna: bool = True) -> ExtensionArrayT: """ Returns the mode(s) of the ExtensionArray. Always returns `ExtensionArray` even if only one value. Parameters ---------- dropna : bool, default True Don't consider counts of NA values. Returns ------- same type as self Sorted, if possible. """ # error: Incompatible return value type (got "Union[ExtensionArray, # ndarray[Any, Any]]", expected "ExtensionArrayT") return mode(self, dropna=dropna) # type: ignore[return-value] def __array_ufunc__(self, ufunc: np.ufunc, method: str, *inputs, **kwargs): if any( isinstance(other, (ABCSeries, ABCIndex, ABCDataFrame)) for other in inputs ): return NotImplemented result = arraylike.maybe_dispatch_ufunc_to_dunder_op( self, ufunc, method, *inputs, **kwargs ) if result is not NotImplemented: return result if "out" in kwargs: return arraylike.dispatch_ufunc_with_out( self, ufunc, method, *inputs, **kwargs ) if method == "reduce": result = arraylike.dispatch_reduction_ufunc( self, ufunc, method, *inputs, **kwargs ) if result is not NotImplemented: return result return arraylike.default_array_ufunc(self, ufunc, method, *inputs, **kwargs) class ExtensionArraySupportsAnyAll(ExtensionArray): def any(self, *, skipna: bool = True) -> bool: raise AbstractMethodError(self) def all(self, *, skipna: bool = True) -> bool: raise AbstractMethodError(self) class ExtensionOpsMixin: """ A base class for linking the operators to their dunder names. .. note:: You may want to set ``__array_priority__`` if you want your implementation to be called when involved in binary operations with NumPy arrays. """ @classmethod def _create_arithmetic_method(cls, op): raise AbstractMethodError(cls) @classmethod def _add_arithmetic_ops(cls) -> None: setattr(cls, "__add__", cls._create_arithmetic_method(operator.add)) setattr(cls, "__radd__", cls._create_arithmetic_method(roperator.radd)) setattr(cls, "__sub__", cls._create_arithmetic_method(operator.sub)) setattr(cls, "__rsub__", cls._create_arithmetic_method(roperator.rsub)) setattr(cls, "__mul__", cls._create_arithmetic_method(operator.mul)) setattr(cls, "__rmul__", cls._create_arithmetic_method(roperator.rmul)) setattr(cls, "__pow__", cls._create_arithmetic_method(operator.pow)) setattr(cls, "__rpow__", cls._create_arithmetic_method(roperator.rpow)) setattr(cls, "__mod__", cls._create_arithmetic_method(operator.mod)) setattr(cls, "__rmod__", cls._create_arithmetic_method(roperator.rmod)) setattr(cls, "__floordiv__", cls._create_arithmetic_method(operator.floordiv)) setattr( cls, "__rfloordiv__", cls._create_arithmetic_method(roperator.rfloordiv) ) setattr(cls, "__truediv__", cls._create_arithmetic_method(operator.truediv)) setattr(cls, "__rtruediv__", cls._create_arithmetic_method(roperator.rtruediv)) setattr(cls, "__divmod__", cls._create_arithmetic_method(divmod)) setattr(cls, "__rdivmod__", cls._create_arithmetic_method(roperator.rdivmod)) @classmethod def _create_comparison_method(cls, op): raise AbstractMethodError(cls) @classmethod def _add_comparison_ops(cls) -> None: setattr(cls, "__eq__", cls._create_comparison_method(operator.eq)) setattr(cls, "__ne__", cls._create_comparison_method(operator.ne)) setattr(cls, "__lt__", cls._create_comparison_method(operator.lt)) setattr(cls, "__gt__", cls._create_comparison_method(operator.gt)) setattr(cls, "__le__", cls._create_comparison_method(operator.le)) setattr(cls, "__ge__", cls._create_comparison_method(operator.ge)) @classmethod def _create_logical_method(cls, op): raise AbstractMethodError(cls) @classmethod def _add_logical_ops(cls) -> None: setattr(cls, "__and__", cls._create_logical_method(operator.and_)) setattr(cls, "__rand__", cls._create_logical_method(roperator.rand_)) setattr(cls, "__or__", cls._create_logical_method(operator.or_)) setattr(cls, "__ror__", cls._create_logical_method(roperator.ror_)) setattr(cls, "__xor__", cls._create_logical_method(operator.xor)) setattr(cls, "__rxor__", cls._create_logical_method(roperator.rxor)) class ExtensionScalarOpsMixin(ExtensionOpsMixin): """ A mixin for defining ops on an ExtensionArray. It is assumed that the underlying scalar objects have the operators already defined. Notes ----- If you have defined a subclass MyExtensionArray(ExtensionArray), then use MyExtensionArray(ExtensionArray, ExtensionScalarOpsMixin) to get the arithmetic operators. After the definition of MyExtensionArray, insert the lines MyExtensionArray._add_arithmetic_ops() MyExtensionArray._add_comparison_ops() to link the operators to your class. .. note:: You may want to set ``__array_priority__`` if you want your implementation to be called when involved in binary operations with NumPy arrays. """ @classmethod def _create_method(cls, op, coerce_to_dtype: bool = True, result_dtype=None): """ A class method that returns a method that will correspond to an operator for an ExtensionArray subclass, by dispatching to the relevant operator defined on the individual elements of the ExtensionArray. Parameters ---------- op : function An operator that takes arguments op(a, b) coerce_to_dtype : bool, default True boolean indicating whether to attempt to convert the result to the underlying ExtensionArray dtype. If it's not possible to create a new ExtensionArray with the values, an ndarray is returned instead. Returns ------- Callable[[Any, Any], Union[ndarray, ExtensionArray]] A method that can be bound to a class. When used, the method receives the two arguments, one of which is the instance of this class, and should return an ExtensionArray or an ndarray. Returning an ndarray may be necessary when the result of the `op` cannot be stored in the ExtensionArray. The dtype of the ndarray uses NumPy's normal inference rules. Examples -------- Given an ExtensionArray subclass called MyExtensionArray, use __add__ = cls._create_method(operator.add) in the class definition of MyExtensionArray to create the operator for addition, that will be based on the operator implementation of the underlying elements of the ExtensionArray """ def _binop(self, other): def convert_values(param): if isinstance(param, ExtensionArray) or is_list_like(param): ovalues = param else: # Assume its an object ovalues = [param] * len(self) return ovalues if isinstance(other, (ABCSeries, ABCIndex, ABCDataFrame)): # rely on pandas to unbox and dispatch to us return NotImplemented lvalues = self rvalues = convert_values(other) # If the operator is not defined for the underlying objects, # a TypeError should be raised res = [op(a, b) for (a, b) in zip(lvalues, rvalues)] def _maybe_convert(arr): if coerce_to_dtype: # https://github.com/pandas-dev/pandas/issues/22850 # We catch all regular exceptions here, and fall back # to an ndarray. res = maybe_cast_to_extension_array(type(self), arr) if not isinstance(res, type(self)): # exception raised in _from_sequence; ensure we have ndarray res = np.asarray(arr) else: res = np.asarray(arr, dtype=result_dtype) return res if op.__name__ in {"divmod", "rdivmod"}: a, b = zip(*res) return _maybe_convert(a), _maybe_convert(b) return _maybe_convert(res) op_name = f"__{op.__name__}__" return set_function_name(_binop, op_name, cls) @classmethod def _create_arithmetic_method(cls, op): return cls._create_method(op) @classmethod def _create_comparison_method(cls, op): return cls._create_method(op, coerce_to_dtype=False, result_dtype=bool)