diff --git "a/hf_env/lib/python3.14/site-packages/numpy/lib/_function_base_impl.py" "b/hf_env/lib/python3.14/site-packages/numpy/lib/_function_base_impl.py" new file mode 100644--- /dev/null +++ "b/hf_env/lib/python3.14/site-packages/numpy/lib/_function_base_impl.py" @@ -0,0 +1,5760 @@ +import builtins +import collections.abc +import functools +import re +import warnings + +import numpy as np +import numpy._core.numeric as _nx +from numpy._core import overrides, transpose +from numpy._core._multiarray_umath import _array_converter +from numpy._core.fromnumeric import any, mean, nonzero, partition, ravel, sum +from numpy._core.multiarray import ( + _monotonicity, + _place, + bincount, + interp as compiled_interp, + interp_complex as compiled_interp_complex, + normalize_axis_index, +) +from numpy._core.numeric import ( + absolute, + arange, + array, + asanyarray, + asarray, + concatenate, + dot, + empty, + integer, + intp, + isscalar, + ndarray, + ones, + take, + where, + zeros_like, +) +from numpy._core.numerictypes import typecodes +from numpy._core.umath import ( + add, + arctan2, + cos, + exp, + floor, + frompyfunc, + less_equal, + minimum, + mod, + not_equal, + pi, + sin, + sqrt, + subtract, +) +from numpy._utils import set_module + +# needed in this module for compatibility +from numpy.lib._histograms_impl import histogram, histogramdd # noqa: F401 +from numpy.lib._twodim_base_impl import diag + +array_function_dispatch = functools.partial( + overrides.array_function_dispatch, module='numpy') + + +__all__ = [ + 'select', 'piecewise', 'trim_zeros', 'copy', 'iterable', 'percentile', + 'diff', 'gradient', 'angle', 'unwrap', 'sort_complex', 'flip', + 'rot90', 'extract', 'place', 'vectorize', 'asarray_chkfinite', 'average', + 'bincount', 'digitize', 'cov', 'corrcoef', + 'median', 'sinc', 'hamming', 'hanning', 'bartlett', + 'blackman', 'kaiser', 'trapezoid', 'i0', + 'meshgrid', 'delete', 'insert', 'append', 'interp', + 'quantile' + ] + +# _QuantileMethods is a dictionary listing all the supported methods to +# compute quantile/percentile. +# +# Below virtual_index refers to the index of the element where the percentile +# would be found in the sorted sample. +# When the sample contains exactly the percentile wanted, the virtual_index is +# an integer to the index of this element. +# When the percentile wanted is in between two elements, the virtual_index +# is made of a integer part (a.k.a 'i' or 'left') and a fractional part +# (a.k.a 'g' or 'gamma') +# +# Each method in _QuantileMethods has two properties +# get_virtual_index : Callable +# The function used to compute the virtual_index. +# fix_gamma : Callable +# A function used for discrete methods to force the index to a specific value. +_QuantileMethods = { + # --- HYNDMAN and FAN METHODS + # Discrete methods + 'inverted_cdf': { + 'get_virtual_index': lambda n, quantiles: _inverted_cdf(n, quantiles), # noqa: PLW0108 + 'fix_gamma': None, # should never be called + }, + 'averaged_inverted_cdf': { + 'get_virtual_index': lambda n, quantiles: (n * quantiles) - 1, + 'fix_gamma': lambda gamma, _: _get_gamma_mask( + shape=gamma.shape, + default_value=1., + conditioned_value=0.5, + where=gamma == 0), + }, + 'closest_observation': { + 'get_virtual_index': lambda n, quantiles: _closest_observation(n, quantiles), # noqa: PLW0108 + 'fix_gamma': None, # should never be called + }, + # Continuous methods + 'interpolated_inverted_cdf': { + 'get_virtual_index': lambda n, quantiles: + _compute_virtual_index(n, quantiles, 0, 1), + 'fix_gamma': lambda gamma, _: gamma, + }, + 'hazen': { + 'get_virtual_index': lambda n, quantiles: + _compute_virtual_index(n, quantiles, 0.5, 0.5), + 'fix_gamma': lambda gamma, _: gamma, + }, + 'weibull': { + 'get_virtual_index': lambda n, quantiles: + _compute_virtual_index(n, quantiles, 0, 0), + 'fix_gamma': lambda gamma, _: gamma, + }, + # Default method. + # To avoid some rounding issues, `(n-1) * quantiles` is preferred to + # `_compute_virtual_index(n, quantiles, 1, 1)`. + # They are mathematically equivalent. + 'linear': { + 'get_virtual_index': lambda n, quantiles: (n - 1) * quantiles, + 'fix_gamma': lambda gamma, _: gamma, + }, + 'median_unbiased': { + 'get_virtual_index': lambda n, quantiles: + _compute_virtual_index(n, quantiles, 1 / 3.0, 1 / 3.0), + 'fix_gamma': lambda gamma, _: gamma, + }, + 'normal_unbiased': { + 'get_virtual_index': lambda n, quantiles: + _compute_virtual_index(n, quantiles, 3 / 8.0, 3 / 8.0), + 'fix_gamma': lambda gamma, _: gamma, + }, + # --- OTHER METHODS + 'lower': { + 'get_virtual_index': lambda n, quantiles: np.floor( + (n - 1) * quantiles).astype(np.intp), + 'fix_gamma': None, # should never be called, index dtype is int + }, + 'higher': { + 'get_virtual_index': lambda n, quantiles: np.ceil( + (n - 1) * quantiles).astype(np.intp), + 'fix_gamma': None, # should never be called, index dtype is int + }, + 'midpoint': { + 'get_virtual_index': lambda n, quantiles: 0.5 * ( + np.floor((n - 1) * quantiles) + + np.ceil((n - 1) * quantiles)), + 'fix_gamma': lambda gamma, index: _get_gamma_mask( + shape=gamma.shape, + default_value=0.5, + conditioned_value=0., + where=index % 1 == 0), + }, + 'nearest': { + 'get_virtual_index': lambda n, quantiles: np.around( + (n - 1) * quantiles).astype(np.intp), + 'fix_gamma': None, + # should never be called, index dtype is int + }} + + +def _rot90_dispatcher(m, k=None, axes=None): + return (m,) + + +@array_function_dispatch(_rot90_dispatcher) +def rot90(m, k=1, axes=(0, 1)): + """ + Rotate an array by 90 degrees in the plane specified by axes. + + Rotation direction is from the first towards the second axis. + This means for a 2D array with the default `k` and `axes`, the + rotation will be counterclockwise. + + Parameters + ---------- + m : array_like + Array of two or more dimensions. + k : integer + Number of times the array is rotated by 90 degrees. + axes : (2,) array_like + The array is rotated in the plane defined by the axes. + Axes must be different. + + Returns + ------- + y : ndarray + A rotated view of `m`. + + See Also + -------- + flip : Reverse the order of elements in an array along the given axis. + fliplr : Flip an array horizontally. + flipud : Flip an array vertically. + + Notes + ----- + ``rot90(m, k=1, axes=(1,0))`` is the reverse of + ``rot90(m, k=1, axes=(0,1))`` + + ``rot90(m, k=1, axes=(1,0))`` is equivalent to + ``rot90(m, k=-1, axes=(0,1))`` + + Examples + -------- + >>> import numpy as np + >>> m = np.array([[1,2],[3,4]], int) + >>> m + array([[1, 2], + [3, 4]]) + >>> np.rot90(m) + array([[2, 4], + [1, 3]]) + >>> np.rot90(m, 2) + array([[4, 3], + [2, 1]]) + >>> m = np.arange(8).reshape((2,2,2)) + >>> np.rot90(m, 1, (1,2)) + array([[[1, 3], + [0, 2]], + [[5, 7], + [4, 6]]]) + + """ + axes = tuple(axes) + if len(axes) != 2: + raise ValueError("len(axes) must be 2.") + + m = asanyarray(m) + + if axes[0] == axes[1] or absolute(axes[0] - axes[1]) == m.ndim: + raise ValueError("Axes must be different.") + + if (axes[0] >= m.ndim or axes[0] < -m.ndim + or axes[1] >= m.ndim or axes[1] < -m.ndim): + raise ValueError(f"Axes={axes} out of range for array of ndim={m.ndim}.") + + k %= 4 + + if k == 0: + return m[:] + if k == 2: + return flip(flip(m, axes[0]), axes[1]) + + axes_list = arange(0, m.ndim) + (axes_list[axes[0]], axes_list[axes[1]]) = (axes_list[axes[1]], + axes_list[axes[0]]) + + if k == 1: + return transpose(flip(m, axes[1]), axes_list) + else: + # k == 3 + return flip(transpose(m, axes_list), axes[1]) + + +def _flip_dispatcher(m, axis=None): + return (m,) + + +@array_function_dispatch(_flip_dispatcher) +def flip(m, axis=None): + """ + Reverse the order of elements in an array along the given axis. + + The shape of the array is preserved, but the elements are reordered. + + Parameters + ---------- + m : array_like + Input array. + axis : None or int or tuple of ints, optional + Axis or axes along which to flip over. The default, + axis=None, will flip over all of the axes of the input array. + If axis is negative it counts from the last to the first axis. + + If axis is a tuple of ints, flipping is performed on all of the axes + specified in the tuple. + + Returns + ------- + out : array_like + A view of `m` with the entries of axis reversed. Since a view is + returned, this operation is done in constant time. + + See Also + -------- + flipud : Flip an array vertically (axis=0). + fliplr : Flip an array horizontally (axis=1). + + Notes + ----- + flip(m, 0) is equivalent to flipud(m). + + flip(m, 1) is equivalent to fliplr(m). + + flip(m, n) corresponds to ``m[...,::-1,...]`` with ``::-1`` at position n. + + flip(m) corresponds to ``m[::-1,::-1,...,::-1]`` with ``::-1`` at all + positions. + + flip(m, (0, 1)) corresponds to ``m[::-1,::-1,...]`` with ``::-1`` at + position 0 and position 1. + + Examples + -------- + >>> import numpy as np + >>> A = np.arange(8).reshape((2,2,2)) + >>> A + array([[[0, 1], + [2, 3]], + [[4, 5], + [6, 7]]]) + >>> np.flip(A, 0) + array([[[4, 5], + [6, 7]], + [[0, 1], + [2, 3]]]) + >>> np.flip(A, 1) + array([[[2, 3], + [0, 1]], + [[6, 7], + [4, 5]]]) + >>> np.flip(A) + array([[[7, 6], + [5, 4]], + [[3, 2], + [1, 0]]]) + >>> np.flip(A, (0, 2)) + array([[[5, 4], + [7, 6]], + [[1, 0], + [3, 2]]]) + >>> rng = np.random.default_rng() + >>> A = rng.normal(size=(3,4,5)) + >>> np.all(np.flip(A,2) == A[:,:,::-1,...]) + True + """ + if not hasattr(m, 'ndim'): + m = asarray(m) + if axis is None: + indexer = (np.s_[::-1],) * m.ndim + else: + axis = _nx.normalize_axis_tuple(axis, m.ndim) + indexer = [np.s_[:]] * m.ndim + for ax in axis: + indexer[ax] = np.s_[::-1] + indexer = tuple(indexer) + return m[indexer] + + +@set_module('numpy') +def iterable(y): + """ + Check whether or not an object can be iterated over. + + Parameters + ---------- + y : object + Input object. + + Returns + ------- + b : bool + Return ``True`` if the object has an iterator method or is a + sequence and ``False`` otherwise. + + + Examples + -------- + >>> import numpy as np + >>> np.iterable([1, 2, 3]) + True + >>> np.iterable(2) + False + + Notes + ----- + In most cases, the results of ``np.iterable(obj)`` are consistent with + ``isinstance(obj, collections.abc.Iterable)``. One notable exception is + the treatment of 0-dimensional arrays:: + + >>> from collections.abc import Iterable + >>> a = np.array(1.0) # 0-dimensional numpy array + >>> isinstance(a, Iterable) + True + >>> np.iterable(a) + False + + """ + try: + iter(y) + except TypeError: + return False + return True + + +def _weights_are_valid(weights, a, axis): + """Validate weights array. + + We assume, weights is not None. + """ + wgt = np.asanyarray(weights) + + # Sanity checks + if a.shape != wgt.shape: + if axis is None: + raise TypeError( + "Axis must be specified when shapes of a and weights " + "differ.") + if wgt.shape != tuple(a.shape[ax] for ax in axis): + raise ValueError( + "Shape of weights must be consistent with " + "shape of a along specified axis.") + + # setup wgt to broadcast along axis + wgt = wgt.transpose(np.argsort(axis)) + wgt = wgt.reshape(tuple((s if ax in axis else 1) + for ax, s in enumerate(a.shape))) + return wgt + + +def _average_dispatcher(a, axis=None, weights=None, returned=None, *, + keepdims=None): + return (a, weights) + + +@array_function_dispatch(_average_dispatcher) +def average(a, axis=None, weights=None, returned=False, *, + keepdims=np._NoValue): + """ + Compute the weighted average along the specified axis. + + Parameters + ---------- + a : array_like + Array containing data to be averaged. If `a` is not an array, a + conversion is attempted. + axis : None or int or tuple of ints, optional + Axis or axes along which to average `a`. The default, + `axis=None`, will average over all of the elements of the input array. + If axis is negative it counts from the last to the first axis. + If axis is a tuple of ints, averaging is performed on all of the axes + specified in the tuple instead of a single axis or all the axes as + before. + weights : array_like, optional + An array of weights associated with the values in `a`. Each value in + `a` contributes to the average according to its associated weight. + The array of weights must be the same shape as `a` if no axis is + specified, otherwise the weights must have dimensions and shape + consistent with `a` along the specified axis. + If `weights=None`, then all data in `a` are assumed to have a + weight equal to one. + The calculation is:: + + avg = sum(a * weights) / sum(weights) + + where the sum is over all included elements. + The only constraint on the values of `weights` is that `sum(weights)` + must not be 0. + returned : bool, optional + Default is `False`. If `True`, the tuple (`average`, `sum_of_weights`) + is returned, otherwise only the average is returned. + If `weights=None`, `sum_of_weights` is equivalent to the number of + elements over which the average is taken. + keepdims : bool, optional + If this is set to True, the axes which are reduced are left + in the result as dimensions with size one. With this option, + the result will broadcast correctly against the original `a`. + *Note:* `keepdims` will not work with instances of `numpy.matrix` + or other classes whose methods do not support `keepdims`. + + .. versionadded:: 1.23.0 + + Returns + ------- + retval, [sum_of_weights] : array_type or double + Return the average along the specified axis. When `returned` is `True`, + return a tuple with the average as the first element and the sum + of the weights as the second element. `sum_of_weights` is of the + same type as `retval`. The result dtype follows a general pattern. + If `weights` is None, the result dtype will be that of `a` , or ``float64`` + if `a` is integral. Otherwise, if `weights` is not None and `a` is non- + integral, the result type will be the type of lowest precision capable of + representing values of both `a` and `weights`. If `a` happens to be + integral, the previous rules still applies but the result dtype will + at least be ``float64``. + + Raises + ------ + ZeroDivisionError + When all weights along axis are zero. See `numpy.ma.average` for a + version robust to this type of error. + TypeError + When `weights` does not have the same shape as `a`, and `axis=None`. + ValueError + When `weights` does not have dimensions and shape consistent with `a` + along specified `axis`. + + See Also + -------- + mean + + ma.average : average for masked arrays -- useful if your data contains + "missing" values + numpy.result_type : Returns the type that results from applying the + numpy type promotion rules to the arguments. + + Examples + -------- + >>> import numpy as np + >>> data = np.arange(1, 5) + >>> data + array([1, 2, 3, 4]) + >>> np.average(data) + 2.5 + >>> np.average(np.arange(1, 11), weights=np.arange(10, 0, -1)) + 4.0 + + >>> data = np.arange(6).reshape((3, 2)) + >>> data + array([[0, 1], + [2, 3], + [4, 5]]) + >>> np.average(data, axis=1, weights=[1./4, 3./4]) + array([0.75, 2.75, 4.75]) + >>> np.average(data, weights=[1./4, 3./4]) + Traceback (most recent call last): + ... + TypeError: Axis must be specified when shapes of a and weights differ. + + With ``keepdims=True``, the following result has shape (3, 1). + + >>> np.average(data, axis=1, keepdims=True) + array([[0.5], + [2.5], + [4.5]]) + + >>> data = np.arange(8).reshape((2, 2, 2)) + >>> data + array([[[0, 1], + [2, 3]], + [[4, 5], + [6, 7]]]) + >>> np.average(data, axis=(0, 1), weights=[[1./4, 3./4], [1., 1./2]]) + array([3.4, 4.4]) + >>> np.average(data, axis=0, weights=[[1./4, 3./4], [1., 1./2]]) + Traceback (most recent call last): + ... + ValueError: Shape of weights must be consistent + with shape of a along specified axis. + """ + a = np.asanyarray(a) + + if axis is not None: + axis = _nx.normalize_axis_tuple(axis, a.ndim, argname="axis") + + if keepdims is np._NoValue: + # Don't pass on the keepdims argument if one wasn't given. + keepdims_kw = {} + else: + keepdims_kw = {'keepdims': keepdims} + + if weights is None: + avg = a.mean(axis, **keepdims_kw) + avg_as_array = np.asanyarray(avg) + scl = avg_as_array.dtype.type(a.size / avg_as_array.size) + else: + wgt = _weights_are_valid(weights=weights, a=a, axis=axis) + + if issubclass(a.dtype.type, (np.integer, np.bool)): + result_dtype = np.result_type(a.dtype, wgt.dtype, 'f8') + else: + result_dtype = np.result_type(a.dtype, wgt.dtype) + + scl = wgt.sum(axis=axis, dtype=result_dtype, **keepdims_kw) + if np.any(scl == 0.0): + raise ZeroDivisionError( + "Weights sum to zero, can't be normalized") + + avg = avg_as_array = np.multiply(a, wgt, + dtype=result_dtype).sum(axis, **keepdims_kw) / scl + + if returned: + if scl.shape != avg_as_array.shape: + scl = np.broadcast_to(scl, avg_as_array.shape, subok=True).copy() + return avg, scl + else: + return avg + + +@set_module('numpy') +def asarray_chkfinite(a, dtype=None, order=None): + """Convert the input to an array, checking for NaNs or Infs. + + Parameters + ---------- + a : array_like + Input data, in any form that can be converted to an array. This + includes lists, lists of tuples, tuples, tuples of tuples, tuples + of lists and ndarrays. Success requires no NaNs or Infs. + dtype : data-type, optional + By default, the data-type is inferred from the input data. + order : {'C', 'F', 'A', 'K'}, optional + The memory layout of the output. + 'C' gives a row-major layout (C-style), + 'F' gives a column-major layout (Fortran-style). + 'C' and 'F' will copy if needed to ensure the output format. + 'A' (any) is equivalent to 'F' if input a is non-contiguous or + Fortran-contiguous, otherwise, it is equivalent to 'C'. + Unlike 'C' or 'F', 'A' does not ensure that the result is contiguous. + 'K' (keep) preserves the input order for the output. + 'C' is the default. + + Returns + ------- + out : ndarray + Array interpretation of `a`. No copy is performed if the input + is already an ndarray. If `a` is a subclass of ndarray, a base + class ndarray is returned. + + Raises + ------ + ValueError + Raises ValueError if `a` contains NaN (Not a Number) or Inf (Infinity). + + See Also + -------- + asarray : Create and array. + asanyarray : Similar function which passes through subclasses. + ascontiguousarray : Convert input to a contiguous array. + asfortranarray : Convert input to an ndarray with column-major + memory order. + fromiter : Create an array from an iterator. + fromfunction : Construct an array by executing a function on grid + positions. + + Examples + -------- + >>> import numpy as np + + Convert a list into an array. If all elements are finite, then + ``asarray_chkfinite`` is identical to ``asarray``. + + >>> a = [1, 2] + >>> np.asarray_chkfinite(a, dtype=float) + array([1., 2.]) + + Raises ValueError if array_like contains Nans or Infs. + + >>> a = [1, 2, np.inf] + >>> try: + ... np.asarray_chkfinite(a) + ... except ValueError: + ... print('ValueError') + ... + ValueError + + """ + a = asarray(a, dtype=dtype, order=order) + if a.dtype.char in typecodes['AllFloat'] and not np.isfinite(a).all(): + raise ValueError( + "array must not contain infs or NaNs") + return a + + +def _piecewise_dispatcher(x, condlist, funclist, *args, **kw): + yield x + # support the undocumented behavior of allowing scalars + if np.iterable(condlist): + yield from condlist + + +@array_function_dispatch(_piecewise_dispatcher) +def piecewise(x, condlist, funclist, *args, **kw): + """ + Evaluate a piecewise-defined function. + + Given a set of conditions and corresponding functions, evaluate each + function on the input data wherever its condition is true. + + Parameters + ---------- + x : ndarray or scalar + The input domain. + condlist : list of bool arrays or bool scalars + Each boolean array corresponds to a function in `funclist`. Wherever + `condlist[i]` is True, `funclist[i](x)` is used as the output value. + + Each boolean array in `condlist` selects a piece of `x`, + and should therefore be of the same shape as `x`. + + The length of `condlist` must correspond to that of `funclist`. + If one extra function is given, i.e. if + ``len(funclist) == len(condlist) + 1``, then that extra function + is the default value, used wherever all conditions are false. + funclist : list of callables, f(x,*args,**kw), or scalars + Each function is evaluated over `x` wherever its corresponding + condition is True. It should take a 1d array as input and give a 1d + array or a scalar value as output. If, instead of a callable, + a scalar is provided then a constant function (``lambda x: scalar``) is + assumed. + args : tuple, optional + Any further arguments given to `piecewise` are passed to the functions + upon execution, i.e., if called ``piecewise(..., ..., 1, 'a')``, then + each function is called as ``f(x, 1, 'a')``. + kw : dict, optional + Keyword arguments used in calling `piecewise` are passed to the + functions upon execution, i.e., if called + ``piecewise(..., ..., alpha=1)``, then each function is called as + ``f(x, alpha=1)``. + + Returns + ------- + out : ndarray + The output is the same shape and type as x and is found by + calling the functions in `funclist` on the appropriate portions of `x`, + as defined by the boolean arrays in `condlist`. Portions not covered + by any condition have a default value of 0. + + + See Also + -------- + choose, select, where + + Notes + ----- + This is similar to choose or select, except that functions are + evaluated on elements of `x` that satisfy the corresponding condition from + `condlist`. + + The result is:: + + |-- + |funclist[0](x[condlist[0]]) + out = |funclist[1](x[condlist[1]]) + |... + |funclist[n2](x[condlist[n2]]) + |-- + + Examples + -------- + >>> import numpy as np + + Define the signum function, which is -1 for ``x < 0`` and +1 for ``x >= 0``. + + >>> x = np.linspace(-2.5, 2.5, 6) + >>> np.piecewise(x, [x < 0, x >= 0], [-1, 1]) + array([-1., -1., -1., 1., 1., 1.]) + + Define the absolute value, which is ``-x`` for ``x <0`` and ``x`` for + ``x >= 0``. + + >>> np.piecewise(x, [x < 0, x >= 0], [lambda x: -x, lambda x: x]) + array([2.5, 1.5, 0.5, 0.5, 1.5, 2.5]) + + Apply the same function to a scalar value. + + >>> y = -2 + >>> np.piecewise(y, [y < 0, y >= 0], [lambda x: -x, lambda x: x]) + array(2) + + """ + x = asanyarray(x) + n2 = len(funclist) + + # undocumented: single condition is promoted to a list of one condition + if isscalar(condlist) or ( + not isinstance(condlist[0], (list, ndarray)) and x.ndim != 0): + condlist = [condlist] + + condlist = asarray(condlist, dtype=bool) + n = len(condlist) + + if n == n2 - 1: # compute the "otherwise" condition. + condelse = ~np.any(condlist, axis=0, keepdims=True) + condlist = np.concatenate([condlist, condelse], axis=0) + n += 1 + elif n != n2: + raise ValueError( + f"with {n} condition(s), either {n} or {n + 1} functions are expected" + ) + + y = zeros_like(x) + for cond, func in zip(condlist, funclist): + if not isinstance(func, collections.abc.Callable): + y[cond] = func + else: + vals = x[cond] + if vals.size > 0: + y[cond] = func(vals, *args, **kw) + + return y + + +def _select_dispatcher(condlist, choicelist, default=None): + yield from condlist + yield from choicelist + + +@array_function_dispatch(_select_dispatcher) +def select(condlist, choicelist, default=0): + """ + Return an array drawn from elements in choicelist, depending on conditions. + + Parameters + ---------- + condlist : list of bool ndarrays + The list of conditions which determine from which array in `choicelist` + the output elements are taken. When multiple conditions are satisfied, + the first one encountered in `condlist` is used. + choicelist : list of ndarrays + The list of arrays from which the output elements are taken. It has + to be of the same length as `condlist`. + default : array_like, optional + The element inserted in `output` when all conditions evaluate to False. + + Returns + ------- + output : ndarray + The output at position m is the m-th element of the array in + `choicelist` where the m-th element of the corresponding array in + `condlist` is True. + + See Also + -------- + where : Return elements from one of two arrays depending on condition. + take, choose, compress, diag, diagonal + + Examples + -------- + >>> import numpy as np + + Beginning with an array of integers from 0 to 5 (inclusive), + elements less than ``3`` are negated, elements greater than ``3`` + are squared, and elements not meeting either of these conditions + (exactly ``3``) are replaced with a `default` value of ``42``. + + >>> x = np.arange(6) + >>> condlist = [x<3, x>3] + >>> choicelist = [-x, x**2] + >>> np.select(condlist, choicelist, 42) + array([ 0, -1, -2, 42, 16, 25]) + + When multiple conditions are satisfied, the first one encountered in + `condlist` is used. + + >>> condlist = [x<=4, x>3] + >>> choicelist = [x, x**2] + >>> np.select(condlist, choicelist, 55) + array([ 0, 1, 2, 3, 4, 25]) + + """ + # Check the size of condlist and choicelist are the same, or abort. + if len(condlist) != len(choicelist): + raise ValueError( + 'list of cases must be same length as list of conditions') + + # Now that the dtype is known, handle the deprecated select([], []) case + if len(condlist) == 0: + raise ValueError("select with an empty condition list is not possible") + + # TODO: This preserves the Python int, float, complex manually to get the + # right `result_type` with NEP 50. Most likely we will grow a better + # way to spell this (and this can be replaced). + choicelist = [ + choice if type(choice) in (int, float, complex) else np.asarray(choice) + for choice in choicelist] + choicelist.append(default if type(default) in (int, float, complex) + else np.asarray(default)) + + try: + dtype = np.result_type(*choicelist) + except TypeError as e: + msg = f'Choicelist and default value do not have a common dtype: {e}' + raise TypeError(msg) from None + + # Convert conditions to arrays and broadcast conditions and choices + # as the shape is needed for the result. Doing it separately optimizes + # for example when all choices are scalars. + condlist = np.broadcast_arrays(*condlist) + choicelist = np.broadcast_arrays(*choicelist) + + # If cond array is not an ndarray in boolean format or scalar bool, abort. + for i, cond in enumerate(condlist): + if cond.dtype.type is not np.bool: + raise TypeError( + f'invalid entry {i} in condlist: should be boolean ndarray') + + if choicelist[0].ndim == 0: + # This may be common, so avoid the call. + result_shape = condlist[0].shape + else: + result_shape = np.broadcast_arrays(condlist[0], choicelist[0])[0].shape + + result = np.full(result_shape, choicelist[-1], dtype) + + # Use np.copyto to burn each choicelist array onto result, using the + # corresponding condlist as a boolean mask. This is done in reverse + # order since the first choice should take precedence. + choicelist = choicelist[-2::-1] + condlist = condlist[::-1] + for choice, cond in zip(choicelist, condlist): + np.copyto(result, choice, where=cond) + + return result + + +def _copy_dispatcher(a, order=None, subok=None): + return (a,) + + +@array_function_dispatch(_copy_dispatcher) +def copy(a, order='K', subok=False): + """ + Return an array copy of the given object. + + Parameters + ---------- + a : array_like + Input data. + order : {'C', 'F', 'A', 'K'}, optional + Controls the memory layout of the copy. 'C' means C-order, + 'F' means F-order, 'A' means 'F' if `a` is Fortran contiguous, + 'C' otherwise. 'K' means match the layout of `a` as closely + as possible. (Note that this function and :meth:`ndarray.copy` are very + similar, but have different default values for their order= + arguments.) + subok : bool, optional + If True, then sub-classes will be passed-through, otherwise the + returned array will be forced to be a base-class array (defaults to False). + + Returns + ------- + arr : ndarray + Array interpretation of `a`. + + See Also + -------- + ndarray.copy : Preferred method for creating an array copy + + Notes + ----- + This is equivalent to: + + >>> np.array(a, copy=True) #doctest: +SKIP + + The copy made of the data is shallow, i.e., for arrays with object dtype, + the new array will point to the same objects. + See Examples from `ndarray.copy`. + + Examples + -------- + >>> import numpy as np + + Create an array x, with a reference y and a copy z: + + >>> x = np.array([1, 2, 3]) + >>> y = x + >>> z = np.copy(x) + + Note that, when we modify x, y changes, but not z: + + >>> x[0] = 10 + >>> x[0] == y[0] + True + >>> x[0] == z[0] + False + + Note that, np.copy clears previously set WRITEABLE=False flag. + + >>> a = np.array([1, 2, 3]) + >>> a.flags["WRITEABLE"] = False + >>> b = np.copy(a) + >>> b.flags["WRITEABLE"] + True + >>> b[0] = 3 + >>> b + array([3, 2, 3]) + """ + return array(a, order=order, subok=subok, copy=True) + +# Basic operations + + +def _gradient_dispatcher(f, *varargs, axis=None, edge_order=None): + yield f + yield from varargs + + +@array_function_dispatch(_gradient_dispatcher) +def gradient(f, *varargs, axis=None, edge_order=1): + """ + Return the gradient of an N-dimensional array. + + The gradient is computed using second order accurate central differences + in the interior points and either first or second order accurate one-sides + (forward or backwards) differences at the boundaries. + The returned gradient hence has the same shape as the input array. + + Parameters + ---------- + f : array_like + An N-dimensional array containing samples of a scalar function. + varargs : list of scalar or array, optional + Spacing between f values. Default unitary spacing for all dimensions. + Spacing can be specified using: + + 1. single scalar to specify a sample distance for all dimensions. + 2. N scalars to specify a constant sample distance for each dimension. + i.e. `dx`, `dy`, `dz`, ... + 3. N arrays to specify the coordinates of the values along each + dimension of F. The length of the array must match the size of + the corresponding dimension + 4. Any combination of N scalars/arrays with the meaning of 2. and 3. + + If `axis` is given, the number of varargs must equal the number of axes + specified in the axis parameter. + Default: 1. (see Examples below). + + edge_order : {1, 2}, optional + Gradient is calculated using N-th order accurate differences + at the boundaries. Default: 1. + axis : None or int or tuple of ints, optional + Gradient is calculated only along the given axis or axes + The default (axis = None) is to calculate the gradient for all the axes + of the input array. axis may be negative, in which case it counts from + the last to the first axis. + + Returns + ------- + gradient : ndarray or tuple of ndarray + A tuple of ndarrays (or a single ndarray if there is only one + dimension) corresponding to the derivatives of f with respect + to each dimension. Each derivative has the same shape as f. + + Examples + -------- + >>> import numpy as np + >>> f = np.array([1, 2, 4, 7, 11, 16]) + >>> np.gradient(f) + array([1. , 1.5, 2.5, 3.5, 4.5, 5. ]) + >>> np.gradient(f, 2) + array([0.5 , 0.75, 1.25, 1.75, 2.25, 2.5 ]) + + Spacing can be also specified with an array that represents the coordinates + of the values F along the dimensions. + For instance a uniform spacing: + + >>> x = np.arange(f.size) + >>> np.gradient(f, x) + array([1. , 1.5, 2.5, 3.5, 4.5, 5. ]) + + Or a non uniform one: + + >>> x = np.array([0., 1., 1.5, 3.5, 4., 6.]) + >>> np.gradient(f, x) + array([1. , 3. , 3.5, 6.7, 6.9, 2.5]) + + For two dimensional arrays, the return will be two arrays ordered by + axis. In this example the first array stands for the gradient in + rows and the second one in columns direction: + + >>> np.gradient(np.array([[1, 2, 6], [3, 4, 5]])) + (array([[ 2., 2., -1.], + [ 2., 2., -1.]]), + array([[1. , 2.5, 4. ], + [1. , 1. , 1. ]])) + + In this example the spacing is also specified: + uniform for axis=0 and non uniform for axis=1 + + >>> dx = 2. + >>> y = [1., 1.5, 3.5] + >>> np.gradient(np.array([[1, 2, 6], [3, 4, 5]]), dx, y) + (array([[ 1. , 1. , -0.5], + [ 1. , 1. , -0.5]]), + array([[2. , 2. , 2. ], + [2. , 1.7, 0.5]])) + + It is possible to specify how boundaries are treated using `edge_order` + + >>> x = np.array([0, 1, 2, 3, 4]) + >>> f = x**2 + >>> np.gradient(f, edge_order=1) + array([1., 2., 4., 6., 7.]) + >>> np.gradient(f, edge_order=2) + array([0., 2., 4., 6., 8.]) + + The `axis` keyword can be used to specify a subset of axes of which the + gradient is calculated + + >>> np.gradient(np.array([[1, 2, 6], [3, 4, 5]]), axis=0) + array([[ 2., 2., -1.], + [ 2., 2., -1.]]) + + The `varargs` argument defines the spacing between sample points in the + input array. It can take two forms: + + 1. An array, specifying coordinates, which may be unevenly spaced: + + >>> x = np.array([0., 2., 3., 6., 8.]) + >>> y = x ** 2 + >>> np.gradient(y, x, edge_order=2) + array([ 0., 4., 6., 12., 16.]) + + 2. A scalar, representing the fixed sample distance: + + >>> dx = 2 + >>> x = np.array([0., 2., 4., 6., 8.]) + >>> y = x ** 2 + >>> np.gradient(y, dx, edge_order=2) + array([ 0., 4., 8., 12., 16.]) + + It's possible to provide different data for spacing along each dimension. + The number of arguments must match the number of dimensions in the input + data. + + >>> dx = 2 + >>> dy = 3 + >>> x = np.arange(0, 6, dx) + >>> y = np.arange(0, 9, dy) + >>> xs, ys = np.meshgrid(x, y) + >>> zs = xs + 2 * ys + >>> np.gradient(zs, dy, dx) # Passing two scalars + (array([[2., 2., 2.], + [2., 2., 2.], + [2., 2., 2.]]), + array([[1., 1., 1.], + [1., 1., 1.], + [1., 1., 1.]])) + + Mixing scalars and arrays is also allowed: + + >>> np.gradient(zs, y, dx) # Passing one array and one scalar + (array([[2., 2., 2.], + [2., 2., 2.], + [2., 2., 2.]]), + array([[1., 1., 1.], + [1., 1., 1.], + [1., 1., 1.]])) + + Notes + ----- + Assuming that :math:`f\\in C^{3}` (i.e., :math:`f` has at least 3 continuous + derivatives) and let :math:`h_{*}` be a non-homogeneous stepsize, we + minimize the "consistency error" :math:`\\eta_{i}` between the true gradient + and its estimate from a linear combination of the neighboring grid-points: + + .. math:: + + \\eta_{i} = f_{i}^{\\left(1\\right)} - + \\left[ \\alpha f\\left(x_{i}\\right) + + \\beta f\\left(x_{i} + h_{d}\\right) + + \\gamma f\\left(x_{i}-h_{s}\\right) + \\right] + + By substituting :math:`f(x_{i} + h_{d})` and :math:`f(x_{i} - h_{s})` + with their Taylor series expansion, this translates into solving + the following the linear system: + + .. math:: + + \\left\\{ + \\begin{array}{r} + \\alpha+\\beta+\\gamma=0 \\\\ + \\beta h_{d}-\\gamma h_{s}=1 \\\\ + \\beta h_{d}^{2}+\\gamma h_{s}^{2}=0 + \\end{array} + \\right. + + The resulting approximation of :math:`f_{i}^{(1)}` is the following: + + .. math:: + + \\hat f_{i}^{(1)} = + \\frac{ + h_{s}^{2}f\\left(x_{i} + h_{d}\\right) + + \\left(h_{d}^{2} - h_{s}^{2}\\right)f\\left(x_{i}\\right) + - h_{d}^{2}f\\left(x_{i}-h_{s}\\right)} + { h_{s}h_{d}\\left(h_{d} + h_{s}\\right)} + + \\mathcal{O}\\left(\\frac{h_{d}h_{s}^{2} + + h_{s}h_{d}^{2}}{h_{d} + + h_{s}}\\right) + + It is worth noting that if :math:`h_{s}=h_{d}` + (i.e., data are evenly spaced) + we find the standard second order approximation: + + .. math:: + + \\hat f_{i}^{(1)}= + \\frac{f\\left(x_{i+1}\\right) - f\\left(x_{i-1}\\right)}{2h} + + \\mathcal{O}\\left(h^{2}\\right) + + With a similar procedure the forward/backward approximations used for + boundaries can be derived. + + References + ---------- + .. [1] Quarteroni A., Sacco R., Saleri F. (2007) Numerical Mathematics + (Texts in Applied Mathematics). New York: Springer. + .. [2] Durran D. R. (1999) Numerical Methods for Wave Equations + in Geophysical Fluid Dynamics. New York: Springer. + .. [3] Fornberg B. (1988) Generation of Finite Difference Formulas on + Arbitrarily Spaced Grids, + Mathematics of Computation 51, no. 184 : 699-706. + `PDF `_. + """ + f = np.asanyarray(f) + N = f.ndim # number of dimensions + + if axis is None: + axes = tuple(range(N)) + else: + axes = _nx.normalize_axis_tuple(axis, N) + + len_axes = len(axes) + n = len(varargs) + if n == 0: + # no spacing argument - use 1 in all axes + dx = [1.0] * len_axes + elif n == 1 and np.ndim(varargs[0]) == 0: + # single scalar for all axes + dx = varargs * len_axes + elif n == len_axes: + # scalar or 1d array for each axis + dx = list(varargs) + for i, distances in enumerate(dx): + distances = np.asanyarray(distances) + if distances.ndim == 0: + continue + elif distances.ndim != 1: + raise ValueError("distances must be either scalars or 1d") + if len(distances) != f.shape[axes[i]]: + raise ValueError("when 1d, distances must match " + "the length of the corresponding dimension") + if np.issubdtype(distances.dtype, np.integer): + # Convert numpy integer types to float64 to avoid modular + # arithmetic in np.diff(distances). + distances = distances.astype(np.float64) + diffx = np.diff(distances) + # if distances are constant reduce to the scalar case + # since it brings a consistent speedup + if (diffx == diffx[0]).all(): + diffx = diffx[0] + dx[i] = diffx + else: + raise TypeError("invalid number of arguments") + + if edge_order > 2: + raise ValueError("'edge_order' greater than 2 not supported") + + # use central differences on interior and one-sided differences on the + # endpoints. This preserves second order-accuracy over the full domain. + + outvals = [] + + # create slice objects --- initially all are [:, :, ..., :] + slice1 = [slice(None)] * N + slice2 = [slice(None)] * N + slice3 = [slice(None)] * N + slice4 = [slice(None)] * N + + otype = f.dtype + if otype.type is np.datetime64: + # the timedelta dtype with the same unit information + otype = np.dtype(otype.name.replace('datetime', 'timedelta')) + # view as timedelta to allow addition + f = f.view(otype) + elif otype.type is np.timedelta64: + pass + elif np.issubdtype(otype, np.inexact): + pass + else: + # All other types convert to floating point. + # First check if f is a numpy integer type; if so, convert f to float64 + # to avoid modular arithmetic when computing the changes in f. + if np.issubdtype(otype, np.integer): + f = f.astype(np.float64) + otype = np.float64 + + for axis, ax_dx in zip(axes, dx): + if f.shape[axis] < edge_order + 1: + raise ValueError( + "Shape of array too small to calculate a numerical gradient, " + "at least (edge_order + 1) elements are required.") + # result allocation + out = np.empty_like(f, dtype=otype) + + # spacing for the current axis + uniform_spacing = np.ndim(ax_dx) == 0 + + # Numerical differentiation: 2nd order interior + slice1[axis] = slice(1, -1) + slice2[axis] = slice(None, -2) + slice3[axis] = slice(1, -1) + slice4[axis] = slice(2, None) + + if uniform_spacing: + out[tuple(slice1)] = (f[tuple(slice4)] - f[tuple(slice2)]) / (2. * ax_dx) + else: + dx1 = ax_dx[0:-1] + dx2 = ax_dx[1:] + a = -(dx2) / (dx1 * (dx1 + dx2)) + b = (dx2 - dx1) / (dx1 * dx2) + c = dx1 / (dx2 * (dx1 + dx2)) + # fix the shape for broadcasting + shape = np.ones(N, dtype=int) + shape[axis] = -1 + + a = a.reshape(shape) + b = b.reshape(shape) + c = c.reshape(shape) + # 1D equivalent -- out[1:-1] = a * f[:-2] + b * f[1:-1] + c * f[2:] + out[tuple(slice1)] = a * f[tuple(slice2)] + b * f[tuple(slice3)] \ + + c * f[tuple(slice4)] + + # Numerical differentiation: 1st order edges + if edge_order == 1: + slice1[axis] = 0 + slice2[axis] = 1 + slice3[axis] = 0 + dx_0 = ax_dx if uniform_spacing else ax_dx[0] + # 1D equivalent -- out[0] = (f[1] - f[0]) / (x[1] - x[0]) + out[tuple(slice1)] = (f[tuple(slice2)] - f[tuple(slice3)]) / dx_0 + + slice1[axis] = -1 + slice2[axis] = -1 + slice3[axis] = -2 + dx_n = ax_dx if uniform_spacing else ax_dx[-1] + # 1D equivalent -- out[-1] = (f[-1] - f[-2]) / (x[-1] - x[-2]) + out[tuple(slice1)] = (f[tuple(slice2)] - f[tuple(slice3)]) / dx_n + + # Numerical differentiation: 2nd order edges + else: + slice1[axis] = 0 + slice2[axis] = 0 + slice3[axis] = 1 + slice4[axis] = 2 + if uniform_spacing: + a = -1.5 / ax_dx + b = 2. / ax_dx + c = -0.5 / ax_dx + else: + dx1 = ax_dx[0] + dx2 = ax_dx[1] + a = -(2. * dx1 + dx2) / (dx1 * (dx1 + dx2)) + b = (dx1 + dx2) / (dx1 * dx2) + c = - dx1 / (dx2 * (dx1 + dx2)) + # 1D equivalent -- out[0] = a * f[0] + b * f[1] + c * f[2] + out[tuple(slice1)] = a * f[tuple(slice2)] + b * f[tuple(slice3)] \ + + c * f[tuple(slice4)] + + slice1[axis] = -1 + slice2[axis] = -3 + slice3[axis] = -2 + slice4[axis] = -1 + if uniform_spacing: + a = 0.5 / ax_dx + b = -2. / ax_dx + c = 1.5 / ax_dx + else: + dx1 = ax_dx[-2] + dx2 = ax_dx[-1] + a = (dx2) / (dx1 * (dx1 + dx2)) + b = - (dx2 + dx1) / (dx1 * dx2) + c = (2. * dx2 + dx1) / (dx2 * (dx1 + dx2)) + # 1D equivalent -- out[-1] = a * f[-3] + b * f[-2] + c * f[-1] + out[tuple(slice1)] = a * f[tuple(slice2)] + b * f[tuple(slice3)] \ + + c * f[tuple(slice4)] + + outvals.append(out) + + # reset the slice object in this dimension to ":" + slice1[axis] = slice(None) + slice2[axis] = slice(None) + slice3[axis] = slice(None) + slice4[axis] = slice(None) + + if len_axes == 1: + return outvals[0] + return tuple(outvals) + + +def _diff_dispatcher(a, n=None, axis=None, prepend=None, append=None): + return (a, prepend, append) + + +@array_function_dispatch(_diff_dispatcher) +def diff(a, n=1, axis=-1, prepend=np._NoValue, append=np._NoValue): + """ + Calculate the n-th discrete difference along the given axis. + + The first difference is given by ``out[i] = a[i+1] - a[i]`` along + the given axis, higher differences are calculated by using `diff` + recursively. + + Parameters + ---------- + a : array_like + Input array + n : int, optional + The number of times values are differenced. If zero, the input + is returned as-is. + axis : int, optional + The axis along which the difference is taken, default is the + last axis. + prepend, append : array_like, optional + Values to prepend or append to `a` along axis prior to + performing the difference. Scalar values are expanded to + arrays with length 1 in the direction of axis and the shape + of the input array in along all other axes. Otherwise the + dimension and shape must match `a` except along axis. + + Returns + ------- + diff : ndarray + The n-th differences. The shape of the output is the same as `a` + except along `axis` where the dimension is smaller by `n`. The + type of the output is the same as the type of the difference + between any two elements of `a`. This is the same as the type of + `a` in most cases. A notable exception is `datetime64`, which + results in a `timedelta64` output array. + + See Also + -------- + gradient, ediff1d, cumsum + + Notes + ----- + Type is preserved for boolean arrays, so the result will contain + `False` when consecutive elements are the same and `True` when they + differ. + + For unsigned integer arrays, the results will also be unsigned. This + should not be surprising, as the result is consistent with + calculating the difference directly: + + >>> u8_arr = np.array([1, 0], dtype=np.uint8) + >>> np.diff(u8_arr) + array([255], dtype=uint8) + >>> u8_arr[1,...] - u8_arr[0,...] + np.uint8(255) + + If this is not desirable, then the array should be cast to a larger + integer type first: + + >>> i16_arr = u8_arr.astype(np.int16) + >>> np.diff(i16_arr) + array([-1], dtype=int16) + + Examples + -------- + >>> import numpy as np + >>> x = np.array([1, 2, 4, 7, 0]) + >>> np.diff(x) + array([ 1, 2, 3, -7]) + >>> np.diff(x, n=2) + array([ 1, 1, -10]) + + >>> x = np.array([[1, 3, 6, 10], [0, 5, 6, 8]]) + >>> np.diff(x) + array([[2, 3, 4], + [5, 1, 2]]) + >>> np.diff(x, axis=0) + array([[-1, 2, 0, -2]]) + + >>> x = np.arange('1066-10-13', '1066-10-16', dtype=np.datetime64) + >>> np.diff(x) + array([1, 1], dtype='timedelta64[D]') + + """ + if n == 0: + return a + if n < 0: + raise ValueError( + "order must be non-negative but got " + repr(n)) + + a = asanyarray(a) + nd = a.ndim + if nd == 0: + raise ValueError("diff requires input that is at least one dimensional") + axis = normalize_axis_index(axis, nd) + + combined = [] + if prepend is not np._NoValue: + prepend = np.asanyarray(prepend) + if prepend.ndim == 0: + shape = list(a.shape) + shape[axis] = 1 + prepend = np.broadcast_to(prepend, tuple(shape)) + combined.append(prepend) + + combined.append(a) + + if append is not np._NoValue: + append = np.asanyarray(append) + if append.ndim == 0: + shape = list(a.shape) + shape[axis] = 1 + append = np.broadcast_to(append, tuple(shape)) + combined.append(append) + + if len(combined) > 1: + a = np.concatenate(combined, axis) + + slice1 = [slice(None)] * nd + slice2 = [slice(None)] * nd + slice1[axis] = slice(1, None) + slice2[axis] = slice(None, -1) + slice1 = tuple(slice1) + slice2 = tuple(slice2) + + op = not_equal if a.dtype == np.bool else subtract + for _ in range(n): + a = op(a[slice1], a[slice2]) + + return a + + +def _interp_dispatcher(x, xp, fp, left=None, right=None, period=None): + return (x, xp, fp) + + +@array_function_dispatch(_interp_dispatcher) +def interp(x, xp, fp, left=None, right=None, period=None): + """ + One-dimensional linear interpolation for monotonically increasing sample points. + + Returns the one-dimensional piecewise linear interpolant to a function + with given discrete data points (`xp`, `fp`), evaluated at `x`. + + Parameters + ---------- + x : array_like + The x-coordinates at which to evaluate the interpolated values. + + xp : 1-D sequence of floats + The x-coordinates of the data points, must be increasing if argument + `period` is not specified. Otherwise, `xp` is internally sorted after + normalizing the periodic boundaries with ``xp = xp % period``. + + fp : 1-D sequence of float or complex + The y-coordinates of the data points, same length as `xp`. + + left : optional float or complex corresponding to fp + Value to return for `x < xp[0]`, default is `fp[0]`. + + right : optional float or complex corresponding to fp + Value to return for `x > xp[-1]`, default is `fp[-1]`. + + period : None or float, optional + A period for the x-coordinates. This parameter allows the proper + interpolation of angular x-coordinates. Parameters `left` and `right` + are ignored if `period` is specified. + + Returns + ------- + y : float or complex (corresponding to fp) or ndarray + The interpolated values, same shape as `x`. + + Raises + ------ + ValueError + If `xp` and `fp` have different length + If `xp` or `fp` are not 1-D sequences + If `period == 0` + + See Also + -------- + scipy.interpolate + + Warnings + -------- + The x-coordinate sequence is expected to be increasing, but this is not + explicitly enforced. However, if the sequence `xp` is non-increasing, + interpolation results are meaningless. + + Note that, since NaN is unsortable, `xp` also cannot contain NaNs. + + A simple check for `xp` being strictly increasing is:: + + np.all(np.diff(xp) > 0) + + Examples + -------- + >>> import numpy as np + >>> xp = [1, 2, 3] + >>> fp = [3, 2, 0] + >>> np.interp(2.5, xp, fp) + 1.0 + >>> np.interp([0, 1, 1.5, 2.72, 3.14], xp, fp) + array([3. , 3. , 2.5 , 0.56, 0. ]) + >>> UNDEF = -99.0 + >>> np.interp(3.14, xp, fp, right=UNDEF) + -99.0 + + Plot an interpolant to the sine function: + + >>> x = np.linspace(0, 2*np.pi, 10) + >>> y = np.sin(x) + >>> xvals = np.linspace(0, 2*np.pi, 50) + >>> yinterp = np.interp(xvals, x, y) + >>> import matplotlib.pyplot as plt + >>> plt.plot(x, y, 'o') + [] + >>> plt.plot(xvals, yinterp, '-x') + [] + >>> plt.show() + + Interpolation with periodic x-coordinates: + + >>> x = [-180, -170, -185, 185, -10, -5, 0, 365] + >>> xp = [190, -190, 350, -350] + >>> fp = [5, 10, 3, 4] + >>> np.interp(x, xp, fp, period=360) + array([7.5 , 5. , 8.75, 6.25, 3. , 3.25, 3.5 , 3.75]) + + Complex interpolation: + + >>> x = [1.5, 4.0] + >>> xp = [2,3,5] + >>> fp = [1.0j, 0, 2+3j] + >>> np.interp(x, xp, fp) + array([0.+1.j , 1.+1.5j]) + + """ + + fp = np.asarray(fp) + + if np.iscomplexobj(fp): + interp_func = compiled_interp_complex + input_dtype = np.complex128 + else: + interp_func = compiled_interp + input_dtype = np.float64 + + if period is not None: + if period == 0: + raise ValueError("period must be a non-zero value") + period = abs(period) + left = None + right = None + + x = np.asarray(x, dtype=np.float64) + xp = np.asarray(xp, dtype=np.float64) + fp = np.asarray(fp, dtype=input_dtype) + + if xp.ndim != 1 or fp.ndim != 1: + raise ValueError("Data points must be 1-D sequences") + if xp.shape[0] != fp.shape[0]: + raise ValueError("fp and xp are not of the same length") + # normalizing periodic boundaries + x = x % period + xp = xp % period + asort_xp = np.argsort(xp) + xp = xp[asort_xp] + fp = fp[asort_xp] + xp = np.concatenate((xp[-1:] - period, xp, xp[0:1] + period)) + fp = np.concatenate((fp[-1:], fp, fp[0:1])) + + return interp_func(x, xp, fp, left, right) + + +def _angle_dispatcher(z, deg=None): + return (z,) + + +@array_function_dispatch(_angle_dispatcher) +def angle(z, deg=False): + """ + Return the angle of the complex argument. + + Parameters + ---------- + z : array_like + A complex number or sequence of complex numbers. + deg : bool, optional + Return angle in degrees if True, radians if False (default). + + Returns + ------- + angle : ndarray or scalar + The counterclockwise angle from the positive real axis on the complex + plane in the range ``(-pi, pi]``, with dtype as numpy.float64. + + See Also + -------- + arctan2 + absolute + + Notes + ----- + This function passes the imaginary and real parts of the argument to + `arctan2` to compute the result; consequently, it follows the convention + of `arctan2` when the magnitude of the argument is zero. See example. + + Examples + -------- + >>> import numpy as np + >>> np.angle([1.0, 1.0j, 1+1j]) # in radians + array([ 0. , 1.57079633, 0.78539816]) # may vary + >>> np.angle(1+1j, deg=True) # in degrees + 45.0 + >>> np.angle([0., -0., complex(0., -0.), complex(-0., -0.)]) # convention + array([ 0. , 3.14159265, -0. , -3.14159265]) + + """ + z = asanyarray(z) + if issubclass(z.dtype.type, _nx.complexfloating): + zimag = z.imag + zreal = z.real + else: + zimag = 0 + zreal = z + + a = arctan2(zimag, zreal) + if deg: + a *= 180 / pi + return a + + +def _unwrap_dispatcher(p, discont=None, axis=None, *, period=None): + return (p,) + + +@array_function_dispatch(_unwrap_dispatcher) +def unwrap(p, discont=None, axis=-1, *, period=2 * pi): + r""" + Unwrap by taking the complement of large deltas with respect to the period. + + This unwraps a signal `p` by changing elements which have an absolute + difference from their predecessor of more than ``max(discont, period/2)`` + to their `period`-complementary values. + + For the default case where `period` is :math:`2\pi` and `discont` is + :math:`\pi`, this unwraps a radian phase `p` such that adjacent differences + are never greater than :math:`\pi` by adding :math:`2k\pi` for some + integer :math:`k`. + + Parameters + ---------- + p : array_like + Input array. + discont : float, optional + Maximum discontinuity between values, default is ``period/2``. + Values below ``period/2`` are treated as if they were ``period/2``. + To have an effect different from the default, `discont` should be + larger than ``period/2``. + axis : int, optional + Axis along which unwrap will operate, default is the last axis. + period : float, optional + Size of the range over which the input wraps. By default, it is + ``2 pi``. + + .. versionadded:: 1.21.0 + + Returns + ------- + out : ndarray + Output array. + + See Also + -------- + rad2deg, deg2rad + + Notes + ----- + If the discontinuity in `p` is smaller than ``period/2``, + but larger than `discont`, no unwrapping is done because taking + the complement would only make the discontinuity larger. + + Examples + -------- + >>> import numpy as np + + >>> phase = np.linspace(0, np.pi, num=5) + >>> phase[3:] += np.pi + >>> phase + array([ 0. , 0.78539816, 1.57079633, 5.49778714, 6.28318531]) # may vary + >>> np.unwrap(phase) + array([ 0. , 0.78539816, 1.57079633, -0.78539816, 0. ]) # may vary + >>> np.unwrap([0, 1, 2, -1, 0], period=4) + array([0, 1, 2, 3, 4]) + >>> np.unwrap([ 1, 2, 3, 4, 5, 6, 1, 2, 3], period=6) + array([1, 2, 3, 4, 5, 6, 7, 8, 9]) + >>> np.unwrap([2, 3, 4, 5, 2, 3, 4, 5], period=4) + array([2, 3, 4, 5, 6, 7, 8, 9]) + >>> phase_deg = np.mod(np.linspace(0 ,720, 19), 360) - 180 + >>> np.unwrap(phase_deg, period=360) + array([-180., -140., -100., -60., -20., 20., 60., 100., 140., + 180., 220., 260., 300., 340., 380., 420., 460., 500., + 540.]) + + This example plots the unwrapping of the wrapped input signal `w`. + First generate `w`, then apply `unwrap` to get `u`. + + >>> t = np.linspace(0, 25, 801) + >>> w = np.mod(1.5 * np.sin(1.1 * t + 0.26) * (1 - t / 6 + (t / 23) ** 3), 2.0) - 1 + >>> u = np.unwrap(w, period=2.0) + + Plot `w` and `u`. + + >>> import matplotlib.pyplot as plt + >>> plt.plot(t, w, label='w (a signal wrapped to [-1, 1])') + >>> plt.plot(t, u, linewidth=2.5, alpha=0.5, label='unwrap(w, period=2)') + >>> plt.xlabel('t') + >>> plt.grid(alpha=0.6) + >>> plt.legend(framealpha=1, shadow=True) + >>> plt.show() + """ + p = asarray(p) + nd = p.ndim + dd = diff(p, axis=axis) + if discont is None: + discont = period / 2 + slice1 = [slice(None, None)] * nd # full slices + slice1[axis] = slice(1, None) + slice1 = tuple(slice1) + dtype = np.result_type(dd, period) + if _nx.issubdtype(dtype, _nx.integer): + interval_high, rem = divmod(period, 2) + boundary_ambiguous = rem == 0 + else: + interval_high = period / 2 + boundary_ambiguous = True + interval_low = -interval_high + ddmod = mod(dd - interval_low, period) + interval_low + if boundary_ambiguous: + # for `mask = (abs(dd) == period/2)`, the above line made + # `ddmod[mask] == -period/2`. correct these such that + # `ddmod[mask] == sign(dd[mask])*period/2`. + _nx.copyto(ddmod, interval_high, + where=(ddmod == interval_low) & (dd > 0)) + ph_correct = ddmod - dd + _nx.copyto(ph_correct, 0, where=abs(dd) < discont) + up = array(p, copy=True, dtype=dtype) + up[slice1] = p[slice1] + ph_correct.cumsum(axis) + return up + + +def _sort_complex(a): + return (a,) + + +@array_function_dispatch(_sort_complex) +def sort_complex(a): + """ + Sort a complex array using the real part first, then the imaginary part. + + Parameters + ---------- + a : array_like + Input array + + Returns + ------- + out : complex ndarray + Always returns a sorted complex array. + + Examples + -------- + >>> import numpy as np + >>> np.sort_complex([5, 3, 6, 2, 1]) + array([1.+0.j, 2.+0.j, 3.+0.j, 5.+0.j, 6.+0.j]) + + >>> np.sort_complex([1 + 2j, 2 - 1j, 3 - 2j, 3 - 3j, 3 + 5j]) + array([1.+2.j, 2.-1.j, 3.-3.j, 3.-2.j, 3.+5.j]) + + """ + b = array(a, copy=True) + b.sort() + if not issubclass(b.dtype.type, _nx.complexfloating): + if b.dtype.char in 'bhBH': + return b.astype('F') + elif b.dtype.char == 'g': + return b.astype('G') + else: + return b.astype('D') + else: + return b + + +def _arg_trim_zeros(filt): + """Return indices of the first and last non-zero element. + + Parameters + ---------- + filt : array_like + Input array. + + Returns + ------- + start, stop : ndarray + Two arrays containing the indices of the first and last non-zero + element in each dimension. + + See also + -------- + trim_zeros + + Examples + -------- + >>> import numpy as np + >>> _arg_trim_zeros(np.array([0, 0, 1, 1, 0])) + (array([2]), array([3])) + """ + nonzero = ( + np.argwhere(filt) + if filt.dtype != np.object_ + # Historically, `trim_zeros` treats `None` in an object array + # as non-zero while argwhere doesn't, account for that + else np.argwhere(filt != 0) + ) + if nonzero.size == 0: + start = stop = np.array([], dtype=np.intp) + else: + start = nonzero.min(axis=0) + stop = nonzero.max(axis=0) + return start, stop + + +def _trim_zeros(filt, trim=None, axis=None): + return (filt,) + + +@array_function_dispatch(_trim_zeros) +def trim_zeros(filt, trim='fb', axis=None): + """Remove values along a dimension which are zero along all other. + + Parameters + ---------- + filt : array_like + Input array. + trim : {"fb", "f", "b"}, optional + A string with 'f' representing trim from front and 'b' to trim from + back. By default, zeros are trimmed on both sides. + Front and back refer to the edges of a dimension, with "front" referring + to the side with the lowest index 0, and "back" referring to the highest + index (or index -1). + axis : int or sequence, optional + If None, `filt` is cropped such that the smallest bounding box is + returned that still contains all values which are not zero. + If an axis is specified, `filt` will be sliced in that dimension only + on the sides specified by `trim`. The remaining area will be the + smallest that still contains all values wich are not zero. + + .. versionadded:: 2.2.0 + + Returns + ------- + trimmed : ndarray or sequence + The result of trimming the input. The number of dimensions and the + input data type are preserved. + + Notes + ----- + For all-zero arrays, the first axis is trimmed first. + + Examples + -------- + >>> import numpy as np + >>> a = np.array((0, 0, 0, 1, 2, 3, 0, 2, 1, 0)) + >>> np.trim_zeros(a) + array([1, 2, 3, 0, 2, 1]) + + >>> np.trim_zeros(a, trim='b') + array([0, 0, 0, ..., 0, 2, 1]) + + Multiple dimensions are supported. + + >>> b = np.array([[0, 0, 2, 3, 0, 0], + ... [0, 1, 0, 3, 0, 0], + ... [0, 0, 0, 0, 0, 0]]) + >>> np.trim_zeros(b) + array([[0, 2, 3], + [1, 0, 3]]) + + >>> np.trim_zeros(b, axis=-1) + array([[0, 2, 3], + [1, 0, 3], + [0, 0, 0]]) + + The input data type is preserved, list/tuple in means list/tuple out. + + >>> np.trim_zeros([0, 1, 2, 0]) + [1, 2] + + """ + filt_ = np.asarray(filt) + + trim = trim.lower() + if trim not in {"fb", "bf", "f", "b"}: + raise ValueError(f"unexpected character(s) in `trim`: {trim!r}") + if axis is None: + axis_tuple = tuple(range(filt_.ndim)) + else: + axis_tuple = _nx.normalize_axis_tuple(axis, filt_.ndim, argname="axis") + + if not axis_tuple: + # No trimming requested -> return input unmodified. + return filt + + start, stop = _arg_trim_zeros(filt_) + stop += 1 # Adjust for slicing + + if start.size == 0: + # filt is all-zero -> assign same values to start and stop so that + # resulting slice will be empty + start = stop = np.zeros(filt_.ndim, dtype=np.intp) + else: + if 'f' not in trim: + start = (None,) * filt_.ndim + if 'b' not in trim: + stop = (None,) * filt_.ndim + + sl = tuple(slice(start[ax], stop[ax]) if ax in axis_tuple else slice(None) + for ax in range(filt_.ndim)) + if len(sl) == 1: + # filt is 1D -> avoid multi-dimensional slicing to preserve + # non-array input types + return filt[sl[0]] + return filt[sl] + + +def _extract_dispatcher(condition, arr): + return (condition, arr) + + +@array_function_dispatch(_extract_dispatcher) +def extract(condition, arr): + """ + Return the elements of an array that satisfy some condition. + + This is equivalent to ``np.compress(ravel(condition), ravel(arr))``. If + `condition` is boolean ``np.extract`` is equivalent to ``arr[condition]``. + + Note that `place` does the exact opposite of `extract`. + + Parameters + ---------- + condition : array_like + An array whose nonzero or True entries indicate the elements of `arr` + to extract. + arr : array_like + Input array of the same size as `condition`. + + Returns + ------- + extract : ndarray + Rank 1 array of values from `arr` where `condition` is True. + + See Also + -------- + take, put, copyto, compress, place + + Examples + -------- + >>> import numpy as np + >>> arr = np.arange(12).reshape((3, 4)) + >>> arr + array([[ 0, 1, 2, 3], + [ 4, 5, 6, 7], + [ 8, 9, 10, 11]]) + >>> condition = np.mod(arr, 3)==0 + >>> condition + array([[ True, False, False, True], + [False, False, True, False], + [False, True, False, False]]) + >>> np.extract(condition, arr) + array([0, 3, 6, 9]) + + + If `condition` is boolean: + + >>> arr[condition] + array([0, 3, 6, 9]) + + """ + return _nx.take(ravel(arr), nonzero(ravel(condition))[0]) + + +def _place_dispatcher(arr, mask, vals): + return (arr, mask, vals) + + +@array_function_dispatch(_place_dispatcher) +def place(arr, mask, vals): + """ + Change elements of an array based on conditional and input values. + + Similar to ``np.copyto(arr, vals, where=mask)``, the difference is that + `place` uses the first N elements of `vals`, where N is the number of + True values in `mask`, while `copyto` uses the elements where `mask` + is True. + + Note that `extract` does the exact opposite of `place`. + + Parameters + ---------- + arr : ndarray + Array to put data into. + mask : array_like + Boolean mask array. Must have the same size as `a`. + vals : 1-D sequence + Values to put into `a`. Only the first N elements are used, where + N is the number of True values in `mask`. If `vals` is smaller + than N, it will be repeated, and if elements of `a` are to be masked, + this sequence must be non-empty. + + See Also + -------- + copyto, put, take, extract + + Examples + -------- + >>> import numpy as np + >>> arr = np.arange(6).reshape(2, 3) + >>> np.place(arr, arr>2, [44, 55]) + >>> arr + array([[ 0, 1, 2], + [44, 55, 44]]) + + """ + return _place(arr, mask, vals) + + +# See https://docs.scipy.org/doc/numpy/reference/c-api.generalized-ufuncs.html +_DIMENSION_NAME = r'\w+' +_CORE_DIMENSION_LIST = f'(?:{_DIMENSION_NAME}(?:,{_DIMENSION_NAME})*)?' +_ARGUMENT = fr'\({_CORE_DIMENSION_LIST}\)' +_ARGUMENT_LIST = f'{_ARGUMENT}(?:,{_ARGUMENT})*' +_SIGNATURE = f'^{_ARGUMENT_LIST}->{_ARGUMENT_LIST}$' + + +def _parse_gufunc_signature(signature): + """ + Parse string signatures for a generalized universal function. + + Arguments + --------- + signature : string + Generalized universal function signature, e.g., ``(m,n),(n,p)->(m,p)`` + for ``np.matmul``. + + Returns + ------- + Tuple of input and output core dimensions parsed from the signature, each + of the form List[Tuple[str, ...]]. + """ + signature = re.sub(r'\s+', '', signature) + + if not re.match(_SIGNATURE, signature): + raise ValueError( + f'not a valid gufunc signature: {signature}') + return tuple([tuple(re.findall(_DIMENSION_NAME, arg)) + for arg in re.findall(_ARGUMENT, arg_list)] + for arg_list in signature.split('->')) + + +def _update_dim_sizes(dim_sizes, arg, core_dims): + """ + Incrementally check and update core dimension sizes for a single argument. + + Arguments + --------- + dim_sizes : Dict[str, int] + Sizes of existing core dimensions. Will be updated in-place. + arg : ndarray + Argument to examine. + core_dims : Tuple[str, ...] + Core dimensions for this argument. + """ + if not core_dims: + return + + num_core_dims = len(core_dims) + if arg.ndim < num_core_dims: + raise ValueError( + '%d-dimensional argument does not have enough ' + 'dimensions for all core dimensions %r' + % (arg.ndim, core_dims)) + + core_shape = arg.shape[-num_core_dims:] + for dim, size in zip(core_dims, core_shape): + if dim in dim_sizes: + if size != dim_sizes[dim]: + raise ValueError( + 'inconsistent size for core dimension %r: %r vs %r' + % (dim, size, dim_sizes[dim])) + else: + dim_sizes[dim] = size + + +def _parse_input_dimensions(args, input_core_dims): + """ + Parse broadcast and core dimensions for vectorize with a signature. + + Arguments + --------- + args : Tuple[ndarray, ...] + Tuple of input arguments to examine. + input_core_dims : List[Tuple[str, ...]] + List of core dimensions corresponding to each input. + + Returns + ------- + broadcast_shape : Tuple[int, ...] + Common shape to broadcast all non-core dimensions to. + dim_sizes : Dict[str, int] + Common sizes for named core dimensions. + """ + broadcast_args = [] + dim_sizes = {} + for arg, core_dims in zip(args, input_core_dims): + _update_dim_sizes(dim_sizes, arg, core_dims) + ndim = arg.ndim - len(core_dims) + dummy_array = np.lib.stride_tricks.as_strided(0, arg.shape[:ndim]) + broadcast_args.append(dummy_array) + broadcast_shape = np.lib._stride_tricks_impl._broadcast_shape( + *broadcast_args + ) + return broadcast_shape, dim_sizes + + +def _calculate_shapes(broadcast_shape, dim_sizes, list_of_core_dims): + """Helper for calculating broadcast shapes with core dimensions.""" + return [broadcast_shape + tuple(dim_sizes[dim] for dim in core_dims) + for core_dims in list_of_core_dims] + + +def _create_arrays(broadcast_shape, dim_sizes, list_of_core_dims, dtypes, + results=None): + """Helper for creating output arrays in vectorize.""" + shapes = _calculate_shapes(broadcast_shape, dim_sizes, list_of_core_dims) + if dtypes is None: + dtypes = [None] * len(shapes) + if results is None: + arrays = tuple(np.empty(shape=shape, dtype=dtype) + for shape, dtype in zip(shapes, dtypes)) + else: + arrays = tuple(np.empty_like(result, shape=shape, dtype=dtype) + for result, shape, dtype + in zip(results, shapes, dtypes)) + return arrays + + +def _get_vectorize_dtype(dtype): + if dtype.char in "SU": + return dtype.char + return dtype + + +@set_module('numpy') +class vectorize: + """ + vectorize(pyfunc=np._NoValue, otypes=None, doc=None, excluded=None, + cache=False, signature=None) + + Returns an object that acts like pyfunc, but takes arrays as input. + + Define a vectorized function which takes a nested sequence of objects or + numpy arrays as inputs and returns a single numpy array or a tuple of numpy + arrays. The vectorized function evaluates `pyfunc` over successive tuples + of the input arrays like the python map function, except it uses the + broadcasting rules of numpy. + + The data type of the output of `vectorized` is determined by calling + the function with the first element of the input. This can be avoided + by specifying the `otypes` argument. + + Parameters + ---------- + pyfunc : callable, optional + A python function or method. + Can be omitted to produce a decorator with keyword arguments. + otypes : str or list of dtypes, optional + The output data type. It must be specified as either a string of + typecode characters or a list of data type specifiers. There should + be one data type specifier for each output. + doc : str, optional + The docstring for the function. If None, the docstring will be the + ``pyfunc.__doc__``. + excluded : set, optional + Set of strings or integers representing the positional or keyword + arguments for which the function will not be vectorized. These will be + passed directly to `pyfunc` unmodified. + + cache : bool, optional + If neither `otypes` nor `signature` are provided, and `cache` is ``True``, then + cache the number of outputs. + + signature : string, optional + Generalized universal function signature, e.g., ``(m,n),(n)->(m)`` for + vectorized matrix-vector multiplication. If provided, ``pyfunc`` will + be called with (and expected to return) arrays with shapes given by the + size of corresponding core dimensions. By default, ``pyfunc`` is + assumed to take scalars as input and output. + + Returns + ------- + out : callable + A vectorized function if ``pyfunc`` was provided, + a decorator otherwise. + + See Also + -------- + frompyfunc : Takes an arbitrary Python function and returns a ufunc + + Notes + ----- + The `vectorize` function is provided primarily for convenience, not for + performance. The implementation is essentially a for loop. + + If neither `otypes` nor `signature` are specified, then a call to the function with + the first argument will be used to determine the number of outputs. The results of + this call will be cached if `cache` is `True` to prevent calling the function + twice. However, to implement the cache, the original function must be wrapped + which will slow down subsequent calls, so only do this if your function is + expensive. + + The new keyword argument interface and `excluded` argument support + further degrades performance. + + References + ---------- + .. [1] :doc:`/reference/c-api/generalized-ufuncs` + + Examples + -------- + >>> import numpy as np + >>> def myfunc(a, b): + ... "Return a-b if a>b, otherwise return a+b" + ... if a > b: + ... return a - b + ... else: + ... return a + b + + >>> vfunc = np.vectorize(myfunc) + >>> vfunc([1, 2, 3, 4], 2) + array([3, 4, 1, 2]) + + The docstring is taken from the input function to `vectorize` unless it + is specified: + + >>> vfunc.__doc__ + 'Return a-b if a>b, otherwise return a+b' + >>> vfunc = np.vectorize(myfunc, doc='Vectorized `myfunc`') + >>> vfunc.__doc__ + 'Vectorized `myfunc`' + + The output type is determined by evaluating the first element of the input, + unless it is specified: + + >>> out = vfunc([1, 2, 3, 4], 2) + >>> type(out[0]) + + >>> vfunc = np.vectorize(myfunc, otypes=[float]) + >>> out = vfunc([1, 2, 3, 4], 2) + >>> type(out[0]) + + + The `excluded` argument can be used to prevent vectorizing over certain + arguments. This can be useful for array-like arguments of a fixed length + such as the coefficients for a polynomial as in `polyval`: + + >>> def mypolyval(p, x): + ... _p = list(p) + ... res = _p.pop(0) + ... while _p: + ... res = res*x + _p.pop(0) + ... return res + + Here, we exclude the zeroth argument from vectorization whether it is + passed by position or keyword. + + >>> vpolyval = np.vectorize(mypolyval, excluded={0, 'p'}) + >>> vpolyval([1, 2, 3], x=[0, 1]) + array([3, 6]) + >>> vpolyval(p=[1, 2, 3], x=[0, 1]) + array([3, 6]) + + The `signature` argument allows for vectorizing functions that act on + non-scalar arrays of fixed length. For example, you can use it for a + vectorized calculation of Pearson correlation coefficient and its p-value: + + >>> import scipy.stats + >>> pearsonr = np.vectorize(scipy.stats.pearsonr, + ... signature='(n),(n)->(),()') + >>> pearsonr([[0, 1, 2, 3]], [[1, 2, 3, 4], [4, 3, 2, 1]]) + (array([ 1., -1.]), array([ 0., 0.])) + + Or for a vectorized convolution: + + >>> convolve = np.vectorize(np.convolve, signature='(n),(m)->(k)') + >>> convolve(np.eye(4), [1, 2, 1]) + array([[1., 2., 1., 0., 0., 0.], + [0., 1., 2., 1., 0., 0.], + [0., 0., 1., 2., 1., 0.], + [0., 0., 0., 1., 2., 1.]]) + + Decorator syntax is supported. The decorator can be called as + a function to provide keyword arguments: + + >>> @np.vectorize + ... def identity(x): + ... return x + ... + >>> identity([0, 1, 2]) + array([0, 1, 2]) + >>> @np.vectorize(otypes=[float]) + ... def as_float(x): + ... return x + ... + >>> as_float([0, 1, 2]) + array([0., 1., 2.]) + """ + def __init__(self, pyfunc=np._NoValue, otypes=None, doc=None, + excluded=None, cache=False, signature=None): + + if (pyfunc != np._NoValue) and (not callable(pyfunc)): + # Splitting the error message to keep + # the length below 79 characters. + part1 = "When used as a decorator, " + part2 = "only accepts keyword arguments." + raise TypeError(part1 + part2) + + self.pyfunc = pyfunc + self.cache = cache + self.signature = signature + if pyfunc != np._NoValue and hasattr(pyfunc, '__name__'): + self.__name__ = pyfunc.__name__ + + self._ufunc = {} # Caching to improve default performance + self._doc = None + self.__doc__ = doc + if doc is None and hasattr(pyfunc, '__doc__'): + self.__doc__ = pyfunc.__doc__ + else: + self._doc = doc + + if isinstance(otypes, str): + for char in otypes: + if char not in typecodes['All']: + raise ValueError(f"Invalid otype specified: {char}") + elif iterable(otypes): + otypes = [_get_vectorize_dtype(_nx.dtype(x)) for x in otypes] + elif otypes is not None: + raise ValueError("Invalid otype specification") + self.otypes = otypes + + # Excluded variable support + if excluded is None: + excluded = set() + self.excluded = set(excluded) + + if signature is not None: + self._in_and_out_core_dims = _parse_gufunc_signature(signature) + else: + self._in_and_out_core_dims = None + + def _init_stage_2(self, pyfunc, *args, **kwargs): + self.__name__ = pyfunc.__name__ + self.pyfunc = pyfunc + if self._doc is None: + self.__doc__ = pyfunc.__doc__ + else: + self.__doc__ = self._doc + + def _call_as_normal(self, *args, **kwargs): + """ + Return arrays with the results of `pyfunc` broadcast (vectorized) over + `args` and `kwargs` not in `excluded`. + """ + excluded = self.excluded + if not kwargs and not excluded: + func = self.pyfunc + vargs = args + else: + # The wrapper accepts only positional arguments: we use `names` and + # `inds` to mutate `the_args` and `kwargs` to pass to the original + # function. + nargs = len(args) + + names = [_n for _n in kwargs if _n not in excluded] + inds = [_i for _i in range(nargs) if _i not in excluded] + the_args = list(args) + + def func(*vargs): + for _n, _i in enumerate(inds): + the_args[_i] = vargs[_n] + kwargs.update(zip(names, vargs[len(inds):])) + return self.pyfunc(*the_args, **kwargs) + + vargs = [args[_i] for _i in inds] + vargs.extend([kwargs[_n] for _n in names]) + + return self._vectorize_call(func=func, args=vargs) + + def __call__(self, *args, **kwargs): + if self.pyfunc is np._NoValue: + self._init_stage_2(*args, **kwargs) + return self + + return self._call_as_normal(*args, **kwargs) + + def _get_ufunc_and_otypes(self, func, args): + """Return (ufunc, otypes).""" + # frompyfunc will fail if args is empty + if not args: + raise ValueError('args can not be empty') + + if self.otypes is not None: + otypes = self.otypes + + # self._ufunc is a dictionary whose keys are the number of + # arguments (i.e. len(args)) and whose values are ufuncs created + # by frompyfunc. len(args) can be different for different calls if + # self.pyfunc has parameters with default values. We only use the + # cache when func is self.pyfunc, which occurs when the call uses + # only positional arguments and no arguments are excluded. + + nin = len(args) + nout = len(self.otypes) + if func is not self.pyfunc or nin not in self._ufunc: + ufunc = frompyfunc(func, nin, nout) + else: + ufunc = None # We'll get it from self._ufunc + if func is self.pyfunc: + ufunc = self._ufunc.setdefault(nin, ufunc) + else: + # Get number of outputs and output types by calling the function on + # the first entries of args. We also cache the result to prevent + # the subsequent call when the ufunc is evaluated. + # Assumes that ufunc first evaluates the 0th elements in the input + # arrays (the input values are not checked to ensure this) + args = [asarray(a) for a in args] + if builtins.any(arg.size == 0 for arg in args): + raise ValueError('cannot call `vectorize` on size 0 inputs ' + 'unless `otypes` is set') + + inputs = [arg.flat[0] for arg in args] + outputs = func(*inputs) + + # Performance note: profiling indicates that -- for simple + # functions at least -- this wrapping can almost double the + # execution time. + # Hence we make it optional. + if self.cache: + _cache = [outputs] + + def _func(*vargs): + if _cache: + return _cache.pop() + else: + return func(*vargs) + else: + _func = func + + if isinstance(outputs, tuple): + nout = len(outputs) + else: + nout = 1 + outputs = (outputs,) + + otypes = ''.join([asarray(outputs[_k]).dtype.char + for _k in range(nout)]) + + # Performance note: profiling indicates that creating the ufunc is + # not a significant cost compared with wrapping so it seems not + # worth trying to cache this. + ufunc = frompyfunc(_func, len(args), nout) + + return ufunc, otypes + + def _vectorize_call(self, func, args): + """Vectorized call to `func` over positional `args`.""" + if self.signature is not None: + res = self._vectorize_call_with_signature(func, args) + elif not args: + res = func() + else: + ufunc, otypes = self._get_ufunc_and_otypes(func=func, args=args) + # gh-29196: `dtype=object` should eventually be removed + args = [asanyarray(a, dtype=object) for a in args] + outputs = ufunc(*args, out=...) + + if ufunc.nout == 1: + res = asanyarray(outputs, dtype=otypes[0]) + else: + res = tuple(asanyarray(x, dtype=t) + for x, t in zip(outputs, otypes)) + return res + + def _vectorize_call_with_signature(self, func, args): + """Vectorized call over positional arguments with a signature.""" + input_core_dims, output_core_dims = self._in_and_out_core_dims + + if len(args) != len(input_core_dims): + raise TypeError('wrong number of positional arguments: ' + 'expected %r, got %r' + % (len(input_core_dims), len(args))) + args = tuple(asanyarray(arg) for arg in args) + + broadcast_shape, dim_sizes = _parse_input_dimensions( + args, input_core_dims) + input_shapes = _calculate_shapes(broadcast_shape, dim_sizes, + input_core_dims) + args = [np.broadcast_to(arg, shape, subok=True) + for arg, shape in zip(args, input_shapes)] + + outputs = None + otypes = self.otypes + nout = len(output_core_dims) + + for index in np.ndindex(*broadcast_shape): + results = func(*(arg[index] for arg in args)) + + n_results = len(results) if isinstance(results, tuple) else 1 + + if nout != n_results: + raise ValueError( + 'wrong number of outputs from pyfunc: expected %r, got %r' + % (nout, n_results)) + + if nout == 1: + results = (results,) + + if outputs is None: + for result, core_dims in zip(results, output_core_dims): + _update_dim_sizes(dim_sizes, result, core_dims) + + outputs = _create_arrays(broadcast_shape, dim_sizes, + output_core_dims, otypes, results) + + for output, result in zip(outputs, results): + output[index] = result + + if outputs is None: + # did not call the function even once + if otypes is None: + raise ValueError('cannot call `vectorize` on size 0 inputs ' + 'unless `otypes` is set') + if builtins.any(dim not in dim_sizes + for dims in output_core_dims + for dim in dims): + raise ValueError('cannot call `vectorize` with a signature ' + 'including new output dimensions on size 0 ' + 'inputs') + outputs = _create_arrays(broadcast_shape, dim_sizes, + output_core_dims, otypes) + + return outputs[0] if nout == 1 else outputs + + +def _cov_dispatcher(m, y=None, rowvar=None, bias=None, ddof=None, + fweights=None, aweights=None, *, dtype=None): + return (m, y, fweights, aweights) + + +@array_function_dispatch(_cov_dispatcher) +def cov(m, y=None, rowvar=True, bias=False, ddof=None, fweights=None, + aweights=None, *, dtype=None): + """ + Estimate a covariance matrix, given data and weights. + + Covariance indicates the level to which two variables vary together. + If we examine N-dimensional samples, :math:`X = [x_1, x_2, ..., x_N]^T`, + then the covariance matrix element :math:`C_{ij}` is the covariance of + :math:`x_i` and :math:`x_j`. The element :math:`C_{ii}` is the variance + of :math:`x_i`. + + See the notes for an outline of the algorithm. + + Parameters + ---------- + m : array_like + A 1-D or 2-D array containing multiple variables and observations. + Each row of `m` represents a variable, and each column a single + observation of all those variables. Also see `rowvar` below. + y : array_like, optional + An additional set of variables and observations. `y` has the same form + as that of `m`. + rowvar : bool, optional + If `rowvar` is True (default), then each row represents a + variable, with observations in the columns. Otherwise, the relationship + is transposed: each column represents a variable, while the rows + contain observations. + bias : bool, optional + Default normalization (False) is by ``(N - 1)``, where ``N`` is the + number of observations given (unbiased estimate). If `bias` is True, + then normalization is by ``N``. These values can be overridden by using + the keyword ``ddof`` in numpy versions >= 1.5. + ddof : int, optional + If not ``None`` the default value implied by `bias` is overridden. + Note that ``ddof=1`` will return the unbiased estimate, even if both + `fweights` and `aweights` are specified, and ``ddof=0`` will return + the simple average. See the notes for the details. The default value + is ``None``. + fweights : array_like, int, optional + 1-D array of integer frequency weights; the number of times each + observation vector should be repeated. + aweights : array_like, optional + 1-D array of observation vector weights. These relative weights are + typically large for observations considered "important" and smaller for + observations considered less "important". If ``ddof=0`` the array of + weights can be used to assign probabilities to observation vectors. + dtype : data-type, optional + Data-type of the result. By default, the return data-type will have + at least `numpy.float64` precision. + + .. versionadded:: 1.20 + + Returns + ------- + out : ndarray + The covariance matrix of the variables. + + See Also + -------- + corrcoef : Normalized covariance matrix + + Notes + ----- + Assume that the observations are in the columns of the observation + array `m` and let ``f = fweights`` and ``a = aweights`` for brevity. The + steps to compute the weighted covariance are as follows:: + + >>> m = np.arange(10, dtype=np.float64) + >>> f = np.arange(10) * 2 + >>> a = np.arange(10) ** 2. + >>> ddof = 1 + >>> w = f * a + >>> v1 = np.sum(w) + >>> v2 = np.sum(w * a) + >>> m -= np.sum(m * w, axis=None, keepdims=True) / v1 + >>> cov = np.dot(m * w, m.T) * v1 / (v1**2 - ddof * v2) + + Note that when ``a == 1``, the normalization factor + ``v1 / (v1**2 - ddof * v2)`` goes over to ``1 / (np.sum(f) - ddof)`` + as it should. + + Examples + -------- + >>> import numpy as np + + Consider two variables, :math:`x_0` and :math:`x_1`, which + correlate perfectly, but in opposite directions: + + >>> x = np.array([[0, 2], [1, 1], [2, 0]]).T + >>> x + array([[0, 1, 2], + [2, 1, 0]]) + + Note how :math:`x_0` increases while :math:`x_1` decreases. The covariance + matrix shows this clearly: + + >>> np.cov(x) + array([[ 1., -1.], + [-1., 1.]]) + + Note that element :math:`C_{0,1}`, which shows the correlation between + :math:`x_0` and :math:`x_1`, is negative. + + Further, note how `x` and `y` are combined: + + >>> x = [-2.1, -1, 4.3] + >>> y = [3, 1.1, 0.12] + >>> X = np.stack((x, y), axis=0) + >>> np.cov(X) + array([[11.71 , -4.286 ], # may vary + [-4.286 , 2.144133]]) + >>> np.cov(x, y) + array([[11.71 , -4.286 ], # may vary + [-4.286 , 2.144133]]) + >>> np.cov(x) + array(11.71) + + """ + # Check inputs + if ddof is not None and ddof != int(ddof): + raise ValueError( + "ddof must be integer") + + # Handles complex arrays too + m = np.asarray(m) + if m.ndim > 2: + raise ValueError("m has more than 2 dimensions") + + if y is not None: + y = np.asarray(y) + if y.ndim > 2: + raise ValueError("y has more than 2 dimensions") + + if dtype is None: + if y is None: + dtype = np.result_type(m, np.float64) + else: + dtype = np.result_type(m, y, np.float64) + + X = array(m, ndmin=2, dtype=dtype) + if not rowvar and m.ndim != 1: + X = X.T + if X.shape[0] == 0: + return np.array([]).reshape(0, 0) + if y is not None: + y = array(y, copy=None, ndmin=2, dtype=dtype) + if not rowvar and y.shape[0] != 1: + y = y.T + X = np.concatenate((X, y), axis=0) + + if ddof is None: + if bias == 0: + ddof = 1 + else: + ddof = 0 + + # Get the product of frequencies and weights + w = None + if fweights is not None: + fweights = np.asarray(fweights, dtype=float) + if not np.all(fweights == np.around(fweights)): + raise TypeError( + "fweights must be integer") + if fweights.ndim > 1: + raise RuntimeError( + "cannot handle multidimensional fweights") + if fweights.shape[0] != X.shape[1]: + raise RuntimeError( + "incompatible numbers of samples and fweights") + if any(fweights < 0): + raise ValueError( + "fweights cannot be negative") + w = fweights + if aweights is not None: + aweights = np.asarray(aweights, dtype=float) + if aweights.ndim > 1: + raise RuntimeError( + "cannot handle multidimensional aweights") + if aweights.shape[0] != X.shape[1]: + raise RuntimeError( + "incompatible numbers of samples and aweights") + if any(aweights < 0): + raise ValueError( + "aweights cannot be negative") + if w is None: + w = aweights + else: + w *= aweights + + avg, w_sum = average(X, axis=1, weights=w, returned=True) + w_sum = w_sum[0] + + # Determine the normalization + if w is None: + fact = X.shape[1] - ddof + elif ddof == 0: + fact = w_sum + elif aweights is None: + fact = w_sum - ddof + else: + fact = w_sum - ddof * sum(w * aweights) / w_sum + + if fact <= 0: + warnings.warn("Degrees of freedom <= 0 for slice", + RuntimeWarning, stacklevel=2) + fact = 0.0 + + X -= avg[:, None] + if w is None: + X_T = X.T + else: + X_T = (X * w).T + c = dot(X, X_T.conj()) + c *= np.true_divide(1, fact) + return c.squeeze() + + +def _corrcoef_dispatcher(x, y=None, rowvar=None, *, + dtype=None): + return (x, y) + + +@array_function_dispatch(_corrcoef_dispatcher) +def corrcoef(x, y=None, rowvar=True, *, + dtype=None): + """ + Return Pearson product-moment correlation coefficients. + + Please refer to the documentation for `cov` for more detail. The + relationship between the correlation coefficient matrix, `R`, and the + covariance matrix, `C`, is + + .. math:: R_{ij} = \\frac{ C_{ij} } { \\sqrt{ C_{ii} C_{jj} } } + + The values of `R` are between -1 and 1, inclusive. + + Parameters + ---------- + x : array_like + A 1-D or 2-D array containing multiple variables and observations. + Each row of `x` represents a variable, and each column a single + observation of all those variables. Also see `rowvar` below. + y : array_like, optional + An additional set of variables and observations. `y` has the same + shape as `x`. + rowvar : bool, optional + If `rowvar` is True (default), then each row represents a + variable, with observations in the columns. Otherwise, the relationship + is transposed: each column represents a variable, while the rows + contain observations. + + dtype : data-type, optional + Data-type of the result. By default, the return data-type will have + at least `numpy.float64` precision. + + .. versionadded:: 1.20 + + Returns + ------- + R : ndarray + The correlation coefficient matrix of the variables. + + See Also + -------- + cov : Covariance matrix + + Notes + ----- + Due to floating point rounding the resulting array may not be Hermitian, + the diagonal elements may not be 1, and the elements may not satisfy the + inequality abs(a) <= 1. The real and imaginary parts are clipped to the + interval [-1, 1] in an attempt to improve on that situation but is not + much help in the complex case. + + Examples + -------- + >>> import numpy as np + + In this example we generate two random arrays, ``xarr`` and ``yarr``, and + compute the row-wise and column-wise Pearson correlation coefficients, + ``R``. Since ``rowvar`` is true by default, we first find the row-wise + Pearson correlation coefficients between the variables of ``xarr``. + + >>> import numpy as np + >>> rng = np.random.default_rng(seed=42) + >>> xarr = rng.random((3, 3)) + >>> xarr + array([[0.77395605, 0.43887844, 0.85859792], + [0.69736803, 0.09417735, 0.97562235], + [0.7611397 , 0.78606431, 0.12811363]]) + >>> R1 = np.corrcoef(xarr) + >>> R1 + array([[ 1. , 0.99256089, -0.68080986], + [ 0.99256089, 1. , -0.76492172], + [-0.68080986, -0.76492172, 1. ]]) + + If we add another set of variables and observations ``yarr``, we can + compute the row-wise Pearson correlation coefficients between the + variables in ``xarr`` and ``yarr``. + + >>> yarr = rng.random((3, 3)) + >>> yarr + array([[0.45038594, 0.37079802, 0.92676499], + [0.64386512, 0.82276161, 0.4434142 ], + [0.22723872, 0.55458479, 0.06381726]]) + >>> R2 = np.corrcoef(xarr, yarr) + >>> R2 + array([[ 1. , 0.99256089, -0.68080986, 0.75008178, -0.934284 , + -0.99004057], + [ 0.99256089, 1. , -0.76492172, 0.82502011, -0.97074098, + -0.99981569], + [-0.68080986, -0.76492172, 1. , -0.99507202, 0.89721355, + 0.77714685], + [ 0.75008178, 0.82502011, -0.99507202, 1. , -0.93657855, + -0.83571711], + [-0.934284 , -0.97074098, 0.89721355, -0.93657855, 1. , + 0.97517215], + [-0.99004057, -0.99981569, 0.77714685, -0.83571711, 0.97517215, + 1. ]]) + + Finally if we use the option ``rowvar=False``, the columns are now + being treated as the variables and we will find the column-wise Pearson + correlation coefficients between variables in ``xarr`` and ``yarr``. + + >>> R3 = np.corrcoef(xarr, yarr, rowvar=False) + >>> R3 + array([[ 1. , 0.77598074, -0.47458546, -0.75078643, -0.9665554 , + 0.22423734], + [ 0.77598074, 1. , -0.92346708, -0.99923895, -0.58826587, + -0.44069024], + [-0.47458546, -0.92346708, 1. , 0.93773029, 0.23297648, + 0.75137473], + [-0.75078643, -0.99923895, 0.93773029, 1. , 0.55627469, + 0.47536961], + [-0.9665554 , -0.58826587, 0.23297648, 0.55627469, 1. , + -0.46666491], + [ 0.22423734, -0.44069024, 0.75137473, 0.47536961, -0.46666491, + 1. ]]) + + """ + c = cov(x, y, rowvar, dtype=dtype) + try: + d = diag(c) + except ValueError: + # scalar covariance + # nan if incorrect value (nan, inf, 0), 1 otherwise + return c / c + stddev = sqrt(d.real) + c /= stddev[:, None] + c /= stddev[None, :] + + # Clip real and imaginary parts to [-1, 1]. This does not guarantee + # abs(a[i,j]) <= 1 for complex arrays, but is the best we can do without + # excessive work. + np.clip(c.real, -1, 1, out=c.real) + if np.iscomplexobj(c): + np.clip(c.imag, -1, 1, out=c.imag) + + return c + + +@set_module('numpy') +def blackman(M): + """ + Return the Blackman window. + + The Blackman window is a taper formed by using the first three + terms of a summation of cosines. It was designed to have close to the + minimal leakage possible. It is close to optimal, only slightly worse + than a Kaiser window. + + Parameters + ---------- + M : int + Number of points in the output window. If zero or less, an empty + array is returned. + + Returns + ------- + out : ndarray + The window, with the maximum value normalized to one (the value one + appears only if the number of samples is odd). + + See Also + -------- + bartlett, hamming, hanning, kaiser + + Notes + ----- + The Blackman window is defined as + + .. math:: w(n) = 0.42 - 0.5 \\cos(2\\pi n/M) + 0.08 \\cos(4\\pi n/M) + + Most references to the Blackman window come from the signal processing + literature, where it is used as one of many windowing functions for + smoothing values. It is also known as an apodization (which means + "removing the foot", i.e. smoothing discontinuities at the beginning + and end of the sampled signal) or tapering function. It is known as a + "near optimal" tapering function, almost as good (by some measures) + as the kaiser window. + + References + ---------- + Blackman, R.B. and Tukey, J.W., (1958) The measurement of power spectra, + Dover Publications, New York. + + Oppenheim, A.V., and R.W. Schafer. Discrete-Time Signal Processing. + Upper Saddle River, NJ: Prentice-Hall, 1999, pp. 468-471. + + Examples + -------- + >>> import numpy as np + >>> import matplotlib.pyplot as plt + >>> np.blackman(12) + array([-1.38777878e-17, 3.26064346e-02, 1.59903635e-01, # may vary + 4.14397981e-01, 7.36045180e-01, 9.67046769e-01, + 9.67046769e-01, 7.36045180e-01, 4.14397981e-01, + 1.59903635e-01, 3.26064346e-02, -1.38777878e-17]) + + Plot the window and the frequency response. + + .. plot:: + :include-source: + + import matplotlib.pyplot as plt + from numpy.fft import fft, fftshift + window = np.blackman(51) + plt.plot(window) + plt.title("Blackman window") + plt.ylabel("Amplitude") + plt.xlabel("Sample") + plt.show() # doctest: +SKIP + + plt.figure() + A = fft(window, 2048) / 25.5 + mag = np.abs(fftshift(A)) + freq = np.linspace(-0.5, 0.5, len(A)) + with np.errstate(divide='ignore', invalid='ignore'): + response = 20 * np.log10(mag) + response = np.clip(response, -100, 100) + plt.plot(freq, response) + plt.title("Frequency response of Blackman window") + plt.ylabel("Magnitude [dB]") + plt.xlabel("Normalized frequency [cycles per sample]") + plt.axis('tight') + plt.show() + + """ + # Ensures at least float64 via 0.0. M should be an integer, but conversion + # to double is safe for a range. + values = np.array([0.0, M]) + M = values[1] + + if M < 1: + return array([], dtype=values.dtype) + if M == 1: + return ones(1, dtype=values.dtype) + n = arange(1 - M, M, 2) + return 0.42 + 0.5 * cos(pi * n / (M - 1)) + 0.08 * cos(2.0 * pi * n / (M - 1)) + + +@set_module('numpy') +def bartlett(M): + """ + Return the Bartlett window. + + The Bartlett window is very similar to a triangular window, except + that the end points are at zero. It is often used in signal + processing for tapering a signal, without generating too much + ripple in the frequency domain. + + Parameters + ---------- + M : int + Number of points in the output window. If zero or less, an + empty array is returned. + + Returns + ------- + out : array + The triangular window, with the maximum value normalized to one + (the value one appears only if the number of samples is odd), with + the first and last samples equal to zero. + + See Also + -------- + blackman, hamming, hanning, kaiser + + Notes + ----- + The Bartlett window is defined as + + .. math:: w(n) = \\frac{2}{M-1} \\left( + \\frac{M-1}{2} - \\left|n - \\frac{M-1}{2}\\right| + \\right) + + Most references to the Bartlett window come from the signal processing + literature, where it is used as one of many windowing functions for + smoothing values. Note that convolution with this window produces linear + interpolation. It is also known as an apodization (which means "removing + the foot", i.e. smoothing discontinuities at the beginning and end of the + sampled signal) or tapering function. The Fourier transform of the + Bartlett window is the product of two sinc functions. Note the excellent + discussion in Kanasewich [2]_. + + References + ---------- + .. [1] M.S. Bartlett, "Periodogram Analysis and Continuous Spectra", + Biometrika 37, 1-16, 1950. + .. [2] E.R. Kanasewich, "Time Sequence Analysis in Geophysics", + The University of Alberta Press, 1975, pp. 109-110. + .. [3] A.V. Oppenheim and R.W. Schafer, "Discrete-Time Signal + Processing", Prentice-Hall, 1999, pp. 468-471. + .. [4] Wikipedia, "Window function", + https://en.wikipedia.org/wiki/Window_function + .. [5] W.H. Press, B.P. Flannery, S.A. Teukolsky, and W.T. Vetterling, + "Numerical Recipes", Cambridge University Press, 1986, page 429. + + Examples + -------- + >>> import numpy as np + >>> import matplotlib.pyplot as plt + >>> np.bartlett(12) + array([ 0. , 0.18181818, 0.36363636, 0.54545455, 0.72727273, # may vary + 0.90909091, 0.90909091, 0.72727273, 0.54545455, 0.36363636, + 0.18181818, 0. ]) + + Plot the window and its frequency response (requires SciPy and matplotlib). + + .. plot:: + :include-source: + + import matplotlib.pyplot as plt + from numpy.fft import fft, fftshift + window = np.bartlett(51) + plt.plot(window) + plt.title("Bartlett window") + plt.ylabel("Amplitude") + plt.xlabel("Sample") + plt.show() + plt.figure() + A = fft(window, 2048) / 25.5 + mag = np.abs(fftshift(A)) + freq = np.linspace(-0.5, 0.5, len(A)) + with np.errstate(divide='ignore', invalid='ignore'): + response = 20 * np.log10(mag) + response = np.clip(response, -100, 100) + plt.plot(freq, response) + plt.title("Frequency response of Bartlett window") + plt.ylabel("Magnitude [dB]") + plt.xlabel("Normalized frequency [cycles per sample]") + plt.axis('tight') + plt.show() + + """ + # Ensures at least float64 via 0.0. M should be an integer, but conversion + # to double is safe for a range. + values = np.array([0.0, M]) + M = values[1] + + if M < 1: + return array([], dtype=values.dtype) + if M == 1: + return ones(1, dtype=values.dtype) + n = arange(1 - M, M, 2) + return where(less_equal(n, 0), 1 + n / (M - 1), 1 - n / (M - 1)) + + +@set_module('numpy') +def hanning(M): + """ + Return the Hanning window. + + The Hanning window is a taper formed by using a weighted cosine. + + Parameters + ---------- + M : int + Number of points in the output window. If zero or less, an + empty array is returned. + + Returns + ------- + out : ndarray, shape(M,) + The window, with the maximum value normalized to one (the value + one appears only if `M` is odd). + + See Also + -------- + bartlett, blackman, hamming, kaiser + + Notes + ----- + The Hanning window is defined as + + .. math:: w(n) = 0.5 - 0.5\\cos\\left(\\frac{2\\pi{n}}{M-1}\\right) + \\qquad 0 \\leq n \\leq M-1 + + The Hanning was named for Julius von Hann, an Austrian meteorologist. + It is also known as the Cosine Bell. Some authors prefer that it be + called a Hann window, to help avoid confusion with the very similar + Hamming window. + + Most references to the Hanning window come from the signal processing + literature, where it is used as one of many windowing functions for + smoothing values. It is also known as an apodization (which means + "removing the foot", i.e. smoothing discontinuities at the beginning + and end of the sampled signal) or tapering function. + + References + ---------- + .. [1] Blackman, R.B. and Tukey, J.W., (1958) The measurement of power + spectra, Dover Publications, New York. + .. [2] E.R. Kanasewich, "Time Sequence Analysis in Geophysics", + The University of Alberta Press, 1975, pp. 106-108. + .. [3] Wikipedia, "Window function", + https://en.wikipedia.org/wiki/Window_function + .. [4] W.H. Press, B.P. Flannery, S.A. Teukolsky, and W.T. Vetterling, + "Numerical Recipes", Cambridge University Press, 1986, page 425. + + Examples + -------- + >>> import numpy as np + >>> np.hanning(12) + array([0. , 0.07937323, 0.29229249, 0.57115742, 0.82743037, + 0.97974649, 0.97974649, 0.82743037, 0.57115742, 0.29229249, + 0.07937323, 0. ]) + + Plot the window and its frequency response. + + .. plot:: + :include-source: + + import matplotlib.pyplot as plt + from numpy.fft import fft, fftshift + window = np.hanning(51) + plt.plot(window) + plt.title("Hann window") + plt.ylabel("Amplitude") + plt.xlabel("Sample") + plt.show() + + plt.figure() + A = fft(window, 2048) / 25.5 + mag = np.abs(fftshift(A)) + freq = np.linspace(-0.5, 0.5, len(A)) + with np.errstate(divide='ignore', invalid='ignore'): + response = 20 * np.log10(mag) + response = np.clip(response, -100, 100) + plt.plot(freq, response) + plt.title("Frequency response of the Hann window") + plt.ylabel("Magnitude [dB]") + plt.xlabel("Normalized frequency [cycles per sample]") + plt.axis('tight') + plt.show() + + """ + # Ensures at least float64 via 0.0. M should be an integer, but conversion + # to double is safe for a range. + values = np.array([0.0, M]) + M = values[1] + + if M < 1: + return array([], dtype=values.dtype) + if M == 1: + return ones(1, dtype=values.dtype) + n = arange(1 - M, M, 2) + return 0.5 + 0.5 * cos(pi * n / (M - 1)) + + +@set_module('numpy') +def hamming(M): + """ + Return the Hamming window. + + The Hamming window is a taper formed by using a weighted cosine. + + Parameters + ---------- + M : int + Number of points in the output window. If zero or less, an + empty array is returned. + + Returns + ------- + out : ndarray + The window, with the maximum value normalized to one (the value + one appears only if the number of samples is odd). + + See Also + -------- + bartlett, blackman, hanning, kaiser + + Notes + ----- + The Hamming window is defined as + + .. math:: w(n) = 0.54 - 0.46\\cos\\left(\\frac{2\\pi{n}}{M-1}\\right) + \\qquad 0 \\leq n \\leq M-1 + + The Hamming was named for R. W. Hamming, an associate of J. W. Tukey + and is described in Blackman and Tukey. It was recommended for + smoothing the truncated autocovariance function in the time domain. + Most references to the Hamming window come from the signal processing + literature, where it is used as one of many windowing functions for + smoothing values. It is also known as an apodization (which means + "removing the foot", i.e. smoothing discontinuities at the beginning + and end of the sampled signal) or tapering function. + + References + ---------- + .. [1] Blackman, R.B. and Tukey, J.W., (1958) The measurement of power + spectra, Dover Publications, New York. + .. [2] E.R. Kanasewich, "Time Sequence Analysis in Geophysics", The + University of Alberta Press, 1975, pp. 109-110. + .. [3] Wikipedia, "Window function", + https://en.wikipedia.org/wiki/Window_function + .. [4] W.H. Press, B.P. Flannery, S.A. Teukolsky, and W.T. Vetterling, + "Numerical Recipes", Cambridge University Press, 1986, page 425. + + Examples + -------- + >>> import numpy as np + >>> np.hamming(12) + array([ 0.08 , 0.15302337, 0.34890909, 0.60546483, 0.84123594, # may vary + 0.98136677, 0.98136677, 0.84123594, 0.60546483, 0.34890909, + 0.15302337, 0.08 ]) + + Plot the window and the frequency response. + + .. plot:: + :include-source: + + import matplotlib.pyplot as plt + from numpy.fft import fft, fftshift + window = np.hamming(51) + plt.plot(window) + plt.title("Hamming window") + plt.ylabel("Amplitude") + plt.xlabel("Sample") + plt.show() + + plt.figure() + A = fft(window, 2048) / 25.5 + mag = np.abs(fftshift(A)) + freq = np.linspace(-0.5, 0.5, len(A)) + response = 20 * np.log10(mag) + response = np.clip(response, -100, 100) + plt.plot(freq, response) + plt.title("Frequency response of Hamming window") + plt.ylabel("Magnitude [dB]") + plt.xlabel("Normalized frequency [cycles per sample]") + plt.axis('tight') + plt.show() + + """ + # Ensures at least float64 via 0.0. M should be an integer, but conversion + # to double is safe for a range. + values = np.array([0.0, M]) + M = values[1] + + if M < 1: + return array([], dtype=values.dtype) + if M == 1: + return ones(1, dtype=values.dtype) + n = arange(1 - M, M, 2) + return 0.54 + 0.46 * cos(pi * n / (M - 1)) + + +## Code from cephes for i0 + +_i0A = [ + -4.41534164647933937950E-18, + 3.33079451882223809783E-17, + -2.43127984654795469359E-16, + 1.71539128555513303061E-15, + -1.16853328779934516808E-14, + 7.67618549860493561688E-14, + -4.85644678311192946090E-13, + 2.95505266312963983461E-12, + -1.72682629144155570723E-11, + 9.67580903537323691224E-11, + -5.18979560163526290666E-10, + 2.65982372468238665035E-9, + -1.30002500998624804212E-8, + 6.04699502254191894932E-8, + -2.67079385394061173391E-7, + 1.11738753912010371815E-6, + -4.41673835845875056359E-6, + 1.64484480707288970893E-5, + -5.75419501008210370398E-5, + 1.88502885095841655729E-4, + -5.76375574538582365885E-4, + 1.63947561694133579842E-3, + -4.32430999505057594430E-3, + 1.05464603945949983183E-2, + -2.37374148058994688156E-2, + 4.93052842396707084878E-2, + -9.49010970480476444210E-2, + 1.71620901522208775349E-1, + -3.04682672343198398683E-1, + 6.76795274409476084995E-1 + ] + +_i0B = [ + -7.23318048787475395456E-18, + -4.83050448594418207126E-18, + 4.46562142029675999901E-17, + 3.46122286769746109310E-17, + -2.82762398051658348494E-16, + -3.42548561967721913462E-16, + 1.77256013305652638360E-15, + 3.81168066935262242075E-15, + -9.55484669882830764870E-15, + -4.15056934728722208663E-14, + 1.54008621752140982691E-14, + 3.85277838274214270114E-13, + 7.18012445138366623367E-13, + -1.79417853150680611778E-12, + -1.32158118404477131188E-11, + -3.14991652796324136454E-11, + 1.18891471078464383424E-11, + 4.94060238822496958910E-10, + 3.39623202570838634515E-9, + 2.26666899049817806459E-8, + 2.04891858946906374183E-7, + 2.89137052083475648297E-6, + 6.88975834691682398426E-5, + 3.36911647825569408990E-3, + 8.04490411014108831608E-1 + ] + + +def _chbevl(x, vals): + b0 = vals[0] + b1 = 0.0 + + for i in range(1, len(vals)): + b2 = b1 + b1 = b0 + b0 = x * b1 - b2 + vals[i] + + return 0.5 * (b0 - b2) + + +def _i0_1(x): + return exp(x) * _chbevl(x / 2.0 - 2, _i0A) + + +def _i0_2(x): + return exp(x) * _chbevl(32.0 / x - 2.0, _i0B) / sqrt(x) + + +def _i0_dispatcher(x): + return (x,) + + +@array_function_dispatch(_i0_dispatcher) +def i0(x): + """ + Modified Bessel function of the first kind, order 0. + + Usually denoted :math:`I_0`. + + Parameters + ---------- + x : array_like of float + Argument of the Bessel function. + + Returns + ------- + out : ndarray, shape = x.shape, dtype = float + The modified Bessel function evaluated at each of the elements of `x`. + + See Also + -------- + scipy.special.i0, scipy.special.iv, scipy.special.ive + + Notes + ----- + The scipy implementation is recommended over this function: it is a + proper ufunc written in C, and more than an order of magnitude faster. + + We use the algorithm published by Clenshaw [1]_ and referenced by + Abramowitz and Stegun [2]_, for which the function domain is + partitioned into the two intervals [0,8] and (8,inf), and Chebyshev + polynomial expansions are employed in each interval. Relative error on + the domain [0,30] using IEEE arithmetic is documented [3]_ as having a + peak of 5.8e-16 with an rms of 1.4e-16 (n = 30000). + + References + ---------- + .. [1] C. W. Clenshaw, "Chebyshev series for mathematical functions", in + *National Physical Laboratory Mathematical Tables*, vol. 5, London: + Her Majesty's Stationery Office, 1962. + .. [2] M. Abramowitz and I. A. Stegun, *Handbook of Mathematical + Functions*, 10th printing, New York: Dover, 1964, pp. 379. + https://personal.math.ubc.ca/~cbm/aands/page_379.htm + .. [3] https://metacpan.org/pod/distribution/Math-Cephes/lib/Math/Cephes.pod#i0:-Modified-Bessel-function-of-order-zero + + Examples + -------- + >>> import numpy as np + >>> np.i0(0.) + array(1.0) + >>> np.i0([0, 1, 2, 3]) + array([1. , 1.26606588, 2.2795853 , 4.88079259]) + + """ + x = np.asanyarray(x) + if x.dtype.kind == 'c': + raise TypeError("i0 not supported for complex values") + if x.dtype.kind != 'f': + x = x.astype(float) + x = np.abs(x) + return piecewise(x, [x <= 8.0], [_i0_1, _i0_2]) + +## End of cephes code for i0 + + +@set_module('numpy') +def kaiser(M, beta): + """ + Return the Kaiser window. + + The Kaiser window is a taper formed by using a Bessel function. + + Parameters + ---------- + M : int + Number of points in the output window. If zero or less, an + empty array is returned. + beta : float + Shape parameter for window. + + Returns + ------- + out : array + The window, with the maximum value normalized to one (the value + one appears only if the number of samples is odd). + + See Also + -------- + bartlett, blackman, hamming, hanning + + Notes + ----- + The Kaiser window is defined as + + .. math:: w(n) = I_0\\left( \\beta \\sqrt{1-\\frac{4n^2}{(M-1)^2}} + \\right)/I_0(\\beta) + + with + + .. math:: \\quad -\\frac{M-1}{2} \\leq n \\leq \\frac{M-1}{2}, + + where :math:`I_0` is the modified zeroth-order Bessel function. + + The Kaiser was named for Jim Kaiser, who discovered a simple + approximation to the DPSS window based on Bessel functions. The Kaiser + window is a very good approximation to the Digital Prolate Spheroidal + Sequence, or Slepian window, which is the transform which maximizes the + energy in the main lobe of the window relative to total energy. + + The Kaiser can approximate many other windows by varying the beta + parameter. + + ==== ======================= + beta Window shape + ==== ======================= + 0 Rectangular + 5 Similar to a Hamming + 6 Similar to a Hanning + 8.6 Similar to a Blackman + ==== ======================= + + A beta value of 14 is probably a good starting point. Note that as beta + gets large, the window narrows, and so the number of samples needs to be + large enough to sample the increasingly narrow spike, otherwise NaNs will + get returned. + + Most references to the Kaiser window come from the signal processing + literature, where it is used as one of many windowing functions for + smoothing values. It is also known as an apodization (which means + "removing the foot", i.e. smoothing discontinuities at the beginning + and end of the sampled signal) or tapering function. + + References + ---------- + .. [1] J. F. Kaiser, "Digital Filters" - Ch 7 in "Systems analysis by + digital computer", Editors: F.F. Kuo and J.F. Kaiser, p 218-285. + John Wiley and Sons, New York, (1966). + .. [2] E.R. Kanasewich, "Time Sequence Analysis in Geophysics", The + University of Alberta Press, 1975, pp. 177-178. + .. [3] Wikipedia, "Window function", + https://en.wikipedia.org/wiki/Window_function + + Examples + -------- + >>> import numpy as np + >>> import matplotlib.pyplot as plt + >>> np.kaiser(12, 14) + array([7.72686684e-06, 3.46009194e-03, 4.65200189e-02, # may vary + 2.29737120e-01, 5.99885316e-01, 9.45674898e-01, + 9.45674898e-01, 5.99885316e-01, 2.29737120e-01, + 4.65200189e-02, 3.46009194e-03, 7.72686684e-06]) + + + Plot the window and the frequency response. + + .. plot:: + :include-source: + + import matplotlib.pyplot as plt + from numpy.fft import fft, fftshift + window = np.kaiser(51, 14) + plt.plot(window) + plt.title("Kaiser window") + plt.ylabel("Amplitude") + plt.xlabel("Sample") + plt.show() + + plt.figure() + A = fft(window, 2048) / 25.5 + mag = np.abs(fftshift(A)) + freq = np.linspace(-0.5, 0.5, len(A)) + response = 20 * np.log10(mag) + response = np.clip(response, -100, 100) + plt.plot(freq, response) + plt.title("Frequency response of Kaiser window") + plt.ylabel("Magnitude [dB]") + plt.xlabel("Normalized frequency [cycles per sample]") + plt.axis('tight') + plt.show() + + """ + # Ensures at least float64 via 0.0. M should be an integer, but conversion + # to double is safe for a range. (Simplified result_type with 0.0 + # strongly typed. result-type is not/less order sensitive, but that mainly + # matters for integers anyway.) + values = np.array([0.0, M, beta]) + M = values[1] + beta = values[2] + + if M == 1: + return np.ones(1, dtype=values.dtype) + n = arange(0, M) + alpha = (M - 1) / 2.0 + return i0(beta * sqrt(1 - ((n - alpha) / alpha)**2.0)) / i0(beta) + + +def _sinc_dispatcher(x): + return (x,) + + +@array_function_dispatch(_sinc_dispatcher) +def sinc(x): + r""" + Return the normalized sinc function. + + The sinc function is equal to :math:`\sin(\pi x)/(\pi x)` for any argument + :math:`x\ne 0`. ``sinc(0)`` takes the limit value 1, making ``sinc`` not + only everywhere continuous but also infinitely differentiable. + + .. note:: + + Note the normalization factor of ``pi`` used in the definition. + This is the most commonly used definition in signal processing. + Use ``sinc(x / np.pi)`` to obtain the unnormalized sinc function + :math:`\sin(x)/x` that is more common in mathematics. + + Parameters + ---------- + x : ndarray + Array (possibly multi-dimensional) of values for which to calculate + ``sinc(x)``. + + Returns + ------- + out : ndarray + ``sinc(x)``, which has the same shape as the input. + + Notes + ----- + The name sinc is short for "sine cardinal" or "sinus cardinalis". + + The sinc function is used in various signal processing applications, + including in anti-aliasing, in the construction of a Lanczos resampling + filter, and in interpolation. + + For bandlimited interpolation of discrete-time signals, the ideal + interpolation kernel is proportional to the sinc function. + + References + ---------- + .. [1] Weisstein, Eric W. "Sinc Function." From MathWorld--A Wolfram Web + Resource. https://mathworld.wolfram.com/SincFunction.html + .. [2] Wikipedia, "Sinc function", + https://en.wikipedia.org/wiki/Sinc_function + + Examples + -------- + >>> import numpy as np + >>> import matplotlib.pyplot as plt + >>> x = np.linspace(-4, 4, 41) + >>> np.sinc(x) + array([-3.89804309e-17, -4.92362781e-02, -8.40918587e-02, # may vary + -8.90384387e-02, -5.84680802e-02, 3.89804309e-17, + 6.68206631e-02, 1.16434881e-01, 1.26137788e-01, + 8.50444803e-02, -3.89804309e-17, -1.03943254e-01, + -1.89206682e-01, -2.16236208e-01, -1.55914881e-01, + 3.89804309e-17, 2.33872321e-01, 5.04551152e-01, + 7.56826729e-01, 9.35489284e-01, 1.00000000e+00, + 9.35489284e-01, 7.56826729e-01, 5.04551152e-01, + 2.33872321e-01, 3.89804309e-17, -1.55914881e-01, + -2.16236208e-01, -1.89206682e-01, -1.03943254e-01, + -3.89804309e-17, 8.50444803e-02, 1.26137788e-01, + 1.16434881e-01, 6.68206631e-02, 3.89804309e-17, + -5.84680802e-02, -8.90384387e-02, -8.40918587e-02, + -4.92362781e-02, -3.89804309e-17]) + + >>> plt.plot(x, np.sinc(x)) + [] + >>> plt.title("Sinc Function") + Text(0.5, 1.0, 'Sinc Function') + >>> plt.ylabel("Amplitude") + Text(0, 0.5, 'Amplitude') + >>> plt.xlabel("X") + Text(0.5, 0, 'X') + >>> plt.show() + + """ + x = np.asanyarray(x) + x = pi * x + # Hope that 1e-20 is sufficient for objects... + eps = np.finfo(x.dtype).eps if x.dtype.kind == "f" else 1e-20 + y = where(x, x, eps) + return sin(y) / y + + +def _ureduce(a, func, keepdims=False, **kwargs): + """ + Internal Function. + Call `func` with `a` as first argument swapping the axes to use extended + axis on functions that don't support it natively. + + Returns result and a.shape with axis dims set to 1. + + Parameters + ---------- + a : array_like + Input array or object that can be converted to an array. + func : callable + Reduction function capable of receiving a single axis argument. + It is called with `a` as first argument followed by `kwargs`. + kwargs : keyword arguments + additional keyword arguments to pass to `func`. + + Returns + ------- + result : tuple + Result of func(a, **kwargs) and a.shape with axis dims set to 1 + which can be used to reshape the result to the same shape a ufunc with + keepdims=True would produce. + + """ + a = np.asanyarray(a) + axis = kwargs.get('axis') + out = kwargs.get('out') + + if keepdims is np._NoValue: + keepdims = False + + nd = a.ndim + if axis is not None: + axis = _nx.normalize_axis_tuple(axis, nd) + + if keepdims and out is not None: + index_out = tuple( + 0 if i in axis else slice(None) for i in range(nd)) + kwargs['out'] = out[(Ellipsis, ) + index_out] + + if len(axis) == 1: + kwargs['axis'] = axis[0] + else: + keep = sorted(set(range(nd)) - set(axis)) + nkeep = len(keep) + + def reshape_arr(a): + # move axis that should not be reduced to front + a = np.moveaxis(a, keep, range(nkeep)) + # merge reduced axis + return a.reshape(a.shape[:nkeep] + (-1,)) + + a = reshape_arr(a) + + weights = kwargs.get("weights") + if weights is not None: + kwargs["weights"] = reshape_arr(weights) + + kwargs['axis'] = -1 + elif keepdims and out is not None: + index_out = (0, ) * nd + kwargs['out'] = out[(Ellipsis, ) + index_out] + + r = func(a, **kwargs) + + if out is not None: + return out + + if keepdims: + if axis is None: + index_r = (np.newaxis, ) * nd + else: + index_r = tuple( + np.newaxis if i in axis else slice(None) + for i in range(nd)) + r = r[(Ellipsis, ) + index_r] + + return r + + +def _median_dispatcher( + a, axis=None, out=None, overwrite_input=None, keepdims=None): + return (a, out) + + +@array_function_dispatch(_median_dispatcher) +def median(a, axis=None, out=None, overwrite_input=False, keepdims=False): + """ + Compute the median along the specified axis. + + Returns the median of the array elements. + + Parameters + ---------- + a : array_like + Input array or object that can be converted to an array. + axis : {int, sequence of int, None}, optional + Axis or axes along which the medians are computed. The default, + axis=None, will compute the median along a flattened version of + the array. If a sequence of axes, the array is first flattened + along the given axes, then the median is computed along the + resulting flattened axis. + out : ndarray, optional + Alternative output array in which to place the result. It must + have the same shape and buffer length as the expected output, + but the type (of the output) will be cast if necessary. + overwrite_input : bool, optional + If True, then allow use of memory of input array `a` for + calculations. The input array will be modified by the call to + `median`. This will save memory when you do not need to preserve + the contents of the input array. Treat the input as undefined, + but it will probably be fully or partially sorted. Default is + False. If `overwrite_input` is ``True`` and `a` is not already an + `ndarray`, an error will be raised. + keepdims : bool, optional + If this is set to True, the axes which are reduced are left + in the result as dimensions with size one. With this option, + the result will broadcast correctly against the original `arr`. + + Returns + ------- + median : ndarray + A new array holding the result. If the input contains integers + or floats smaller than ``float64``, then the output data-type is + ``np.float64``. Otherwise, the data-type of the output is the + same as that of the input. If `out` is specified, that array is + returned instead. + + See Also + -------- + mean, percentile + + Notes + ----- + Given a vector ``V`` of length ``N``, the median of ``V`` is the + middle value of a sorted copy of ``V``, ``V_sorted`` - i + e., ``V_sorted[(N-1)/2]``, when ``N`` is odd, and the average of the + two middle values of ``V_sorted`` when ``N`` is even. + + Examples + -------- + >>> import numpy as np + >>> a = np.array([[10, 7, 4], [3, 2, 1]]) + >>> a + array([[10, 7, 4], + [ 3, 2, 1]]) + >>> np.median(a) + np.float64(3.5) + >>> np.median(a, axis=0) + array([6.5, 4.5, 2.5]) + >>> np.median(a, axis=1) + array([7., 2.]) + >>> np.median(a, axis=(0, 1)) + np.float64(3.5) + >>> m = np.median(a, axis=0) + >>> out = np.zeros_like(m) + >>> np.median(a, axis=0, out=m) + array([6.5, 4.5, 2.5]) + >>> m + array([6.5, 4.5, 2.5]) + >>> b = a.copy() + >>> np.median(b, axis=1, overwrite_input=True) + array([7., 2.]) + >>> assert not np.all(a==b) + >>> b = a.copy() + >>> np.median(b, axis=None, overwrite_input=True) + np.float64(3.5) + >>> assert not np.all(a==b) + + """ + return _ureduce(a, func=_median, keepdims=keepdims, axis=axis, out=out, + overwrite_input=overwrite_input) + + +def _median(a, axis=None, out=None, overwrite_input=False): + # can't be reasonably be implemented in terms of percentile as we have to + # call mean to not break astropy + a = np.asanyarray(a) + + # Set the partition indexes + if axis is None: + sz = a.size + else: + sz = a.shape[axis] + if sz % 2 == 0: + szh = sz // 2 + kth = [szh - 1, szh] + else: + kth = [(sz - 1) // 2] + + # We have to check for NaNs (as of writing 'M' doesn't actually work). + supports_nans = np.issubdtype(a.dtype, np.inexact) or a.dtype.kind in 'Mm' + if supports_nans: + kth.append(-1) + + if overwrite_input: + if axis is None: + part = a.ravel() + part.partition(kth) + else: + a.partition(kth, axis=axis) + part = a + else: + part = partition(a, kth, axis=axis) + + if part.shape == (): + # make 0-D arrays work + return part.item() + if axis is None: + axis = 0 + + indexer = [slice(None)] * part.ndim + index = part.shape[axis] // 2 + if part.shape[axis] % 2 == 1: + # index with slice to allow mean (below) to work + indexer[axis] = slice(index, index + 1) + else: + indexer[axis] = slice(index - 1, index + 1) + indexer = tuple(indexer) + + # Use mean in both odd and even case to coerce data type, + # using out array if needed. + rout = mean(part[indexer], axis=axis, out=out) + if supports_nans and sz > 0: + # If nans are possible, warn and replace by nans like mean would. + rout = np.lib._utils_impl._median_nancheck(part, rout, axis) + + return rout + + +def _percentile_dispatcher(a, q, axis=None, out=None, overwrite_input=None, + method=None, keepdims=None, *, weights=None): + return (a, q, out, weights) + + +@array_function_dispatch(_percentile_dispatcher) +def percentile(a, + q, + axis=None, + out=None, + overwrite_input=False, + method="linear", + keepdims=False, + *, + weights=None): + """ + Compute the q-th percentile of the data along the specified axis. + + Returns the q-th percentile(s) of the array elements. + + Parameters + ---------- + a : array_like of real numbers + Input array or object that can be converted to an array. + q : array_like of float + Percentage or sequence of percentages for the percentiles to compute. + Values must be between 0 and 100 inclusive. + axis : {int, tuple of int, None}, optional + Axis or axes along which the percentiles are computed. The + default is to compute the percentile(s) along a flattened + version of the array. + out : ndarray, optional + Alternative output array in which to place the result. It must + have the same shape and buffer length as the expected output, + but the type (of the output) will be cast if necessary. + overwrite_input : bool, optional + If True, then allow the input array `a` to be modified by intermediate + calculations, to save memory. In this case, the contents of the input + `a` after this function completes is undefined. + method : str, optional + This parameter specifies the method to use for estimating the + percentile. There are many different methods, some unique to NumPy. + See the notes for explanation. The options sorted by their R type + as summarized in the H&F paper [1]_ are: + + 1. 'inverted_cdf' + 2. 'averaged_inverted_cdf' + 3. 'closest_observation' + 4. 'interpolated_inverted_cdf' + 5. 'hazen' + 6. 'weibull' + 7. 'linear' (default) + 8. 'median_unbiased' + 9. 'normal_unbiased' + + The first three methods are discontinuous. NumPy further defines the + following discontinuous variations of the default 'linear' (7.) option: + + * 'lower' + * 'higher', + * 'midpoint' + * 'nearest' + + .. versionchanged:: 1.22.0 + This argument was previously called "interpolation" and only + offered the "linear" default and last four options. + + keepdims : bool, optional + If this is set to True, the axes which are reduced are left in + the result as dimensions with size one. With this option, the + result will broadcast correctly against the original array `a`. + + weights : array_like, optional + An array of weights associated with the values in `a`. Each value in + `a` contributes to the percentile according to its associated weight. + The weights array can either be 1-D (in which case its length must be + the size of `a` along the given axis) or of the same shape as `a`. + If `weights=None`, then all data in `a` are assumed to have a + weight equal to one. + Only `method="inverted_cdf"` supports weights. + See the notes for more details. + + .. versionadded:: 2.0.0 + + Returns + ------- + percentile : scalar or ndarray + If `q` is a single percentile and `axis=None`, then the result + is a scalar. If multiple percentiles are given, first axis of + the result corresponds to the percentiles. The other axes are + the axes that remain after the reduction of `a`. If the input + contains integers or floats smaller than ``float64``, the output + data-type is ``float64``. Otherwise, the output data-type is the + same as that of the input. If `out` is specified, that array is + returned instead. + + See Also + -------- + mean + median : equivalent to ``percentile(..., 50)`` + nanpercentile + quantile : equivalent to percentile, except q in the range [0, 1]. + + Notes + ----- + The behavior of `numpy.percentile` with percentage `q` is + that of `numpy.quantile` with argument ``q/100``. + For more information, please see `numpy.quantile`. + + Examples + -------- + >>> import numpy as np + >>> a = np.array([[10, 7, 4], [3, 2, 1]]) + >>> a + array([[10, 7, 4], + [ 3, 2, 1]]) + >>> np.percentile(a, 50) + 3.5 + >>> np.percentile(a, 50, axis=0) + array([6.5, 4.5, 2.5]) + >>> np.percentile(a, 50, axis=1) + array([7., 2.]) + >>> np.percentile(a, 50, axis=1, keepdims=True) + array([[7.], + [2.]]) + + >>> m = np.percentile(a, 50, axis=0) + >>> out = np.zeros_like(m) + >>> np.percentile(a, 50, axis=0, out=out) + array([6.5, 4.5, 2.5]) + >>> m + array([6.5, 4.5, 2.5]) + + >>> b = a.copy() + >>> np.percentile(b, 50, axis=1, overwrite_input=True) + array([7., 2.]) + >>> assert not np.all(a == b) + + The different methods can be visualized graphically: + + .. plot:: + + import matplotlib.pyplot as plt + + a = np.arange(4) + p = np.linspace(0, 100, 6001) + ax = plt.gca() + lines = [ + ('linear', '-', 'C0'), + ('inverted_cdf', ':', 'C1'), + # Almost the same as `inverted_cdf`: + ('averaged_inverted_cdf', '-.', 'C1'), + ('closest_observation', ':', 'C2'), + ('interpolated_inverted_cdf', '--', 'C1'), + ('hazen', '--', 'C3'), + ('weibull', '-.', 'C4'), + ('median_unbiased', '--', 'C5'), + ('normal_unbiased', '-.', 'C6'), + ] + for method, style, color in lines: + ax.plot( + p, np.percentile(a, p, method=method), + label=method, linestyle=style, color=color) + ax.set( + title='Percentiles for different methods and data: ' + str(a), + xlabel='Percentile', + ylabel='Estimated percentile value', + yticks=a) + ax.legend(bbox_to_anchor=(1.03, 1)) + plt.tight_layout() + plt.show() + + References + ---------- + .. [1] R. J. Hyndman and Y. Fan, + "Sample quantiles in statistical packages," + The American Statistician, 50(4), pp. 361-365, 1996 + + """ + a = np.asanyarray(a) + if a.dtype.kind == "c": + raise TypeError("a must be an array of real numbers") + + weak_q = type(q) in (int, float) # use weak promotion for final result type + q = np.true_divide(q, 100, out=...) + if not _quantile_is_valid(q): + raise ValueError("Percentiles must be in the range [0, 100]") + + if weights is not None: + if method != "inverted_cdf": + msg = ("Only method 'inverted_cdf' supports weights. " + f"Got: {method}.") + raise ValueError(msg) + if axis is not None: + axis = _nx.normalize_axis_tuple(axis, a.ndim, argname="axis") + weights = _weights_are_valid(weights=weights, a=a, axis=axis) + if np.any(weights < 0): + raise ValueError("Weights must be non-negative.") + + return _quantile_unchecked( + a, q, axis, out, overwrite_input, method, keepdims, weights, weak_q) + + +def _quantile_dispatcher(a, q, axis=None, out=None, overwrite_input=None, + method=None, keepdims=None, *, weights=None): + return (a, q, out, weights) + + +@array_function_dispatch(_quantile_dispatcher) +def quantile(a, + q, + axis=None, + out=None, + overwrite_input=False, + method="linear", + keepdims=False, + *, + weights=None): + """ + Compute the q-th quantile of the data along the specified axis. + + Parameters + ---------- + a : array_like of real numbers + Input array or object that can be converted to an array. + q : array_like of float + Probability or sequence of probabilities of the quantiles to compute. + Values must be between 0 and 1 inclusive. + axis : {int, tuple of int, None}, optional + Axis or axes along which the quantiles are computed. The default is + to compute the quantile(s) along a flattened version of the array. + out : ndarray, optional + Alternative output array in which to place the result. It must have + the same shape and buffer length as the expected output, but the + type (of the output) will be cast if necessary. + overwrite_input : bool, optional + If True, then allow the input array `a` to be modified by + intermediate calculations, to save memory. In this case, the + contents of the input `a` after this function completes is + undefined. + method : str, optional + This parameter specifies the method to use for estimating the + quantile. There are many different methods, some unique to NumPy. + The recommended options, numbered as they appear in [1]_, are: + + 1. 'inverted_cdf' + 2. 'averaged_inverted_cdf' + 3. 'closest_observation' + 4. 'interpolated_inverted_cdf' + 5. 'hazen' + 6. 'weibull' + 7. 'linear' (default) + 8. 'median_unbiased' + 9. 'normal_unbiased' + + The first three methods are discontinuous. For backward compatibility + with previous versions of NumPy, the following discontinuous variations + of the default 'linear' (7.) option are available: + + * 'lower' + * 'higher', + * 'midpoint' + * 'nearest' + + See Notes for details. + + .. versionchanged:: 1.22.0 + This argument was previously called "interpolation" and only + offered the "linear" default and last four options. + + keepdims : bool, optional + If this is set to True, the axes which are reduced are left in + the result as dimensions with size one. With this option, the + result will broadcast correctly against the original array `a`. + + weights : array_like, optional + An array of weights associated with the values in `a`. Each value in + `a` contributes to the quantile according to its associated weight. + The weights array can either be 1-D (in which case its length must be + the size of `a` along the given axis) or of the same shape as `a`. + If `weights=None`, then all data in `a` are assumed to have a + weight equal to one. + Only `method="inverted_cdf"` supports weights. + See the notes for more details. + + .. versionadded:: 2.0.0 + + Returns + ------- + quantile : scalar or ndarray + If `q` is a single probability and `axis=None`, then the result + is a scalar. If multiple probability levels are given, first axis + of the result corresponds to the quantiles. The other axes are + the axes that remain after the reduction of `a`. If the input + contains integers or floats smaller than ``float64``, the output + data-type is ``float64``. Otherwise, the output data-type is the + same as that of the input. If `out` is specified, that array is + returned instead. + + See Also + -------- + mean + percentile : equivalent to quantile, but with q in the range [0, 100]. + median : equivalent to ``quantile(..., 0.5)`` + nanquantile + + Notes + ----- + Given a sample `a` from an underlying distribution, `quantile` provides a + nonparametric estimate of the inverse cumulative distribution function. + + By default, this is done by interpolating between adjacent elements in + ``y``, a sorted copy of `a`:: + + (1-g)*y[j] + g*y[j+1] + + where the index ``j`` and coefficient ``g`` are the integral and + fractional components of ``q * (n-1)``, and ``n`` is the number of + elements in the sample. + + This is a special case of Equation 1 of H&F [1]_. More generally, + + - ``j = (q*n + m - 1) // 1``, and + - ``g = (q*n + m - 1) % 1``, + + where ``m`` may be defined according to several different conventions. + The preferred convention may be selected using the ``method`` parameter: + + =============================== =============== =============== + ``method`` number in H&F ``m`` + =============================== =============== =============== + ``interpolated_inverted_cdf`` 4 ``0`` + ``hazen`` 5 ``1/2`` + ``weibull`` 6 ``q`` + ``linear`` (default) 7 ``1 - q`` + ``median_unbiased`` 8 ``q/3 + 1/3`` + ``normal_unbiased`` 9 ``q/4 + 3/8`` + =============================== =============== =============== + + Note that indices ``j`` and ``j + 1`` are clipped to the range ``0`` to + ``n - 1`` when the results of the formula would be outside the allowed + range of non-negative indices. The ``- 1`` in the formulas for ``j`` and + ``g`` accounts for Python's 0-based indexing. + + The table above includes only the estimators from H&F that are continuous + functions of probability `q` (estimators 4-9). NumPy also provides the + three discontinuous estimators from H&F (estimators 1-3), where ``j`` is + defined as above, ``m`` is defined as follows, and ``g`` is a function + of the real-valued ``index = q*n + m - 1`` and ``j``. + + 1. ``inverted_cdf``: ``m = 0`` and ``g = int(index - j > 0)`` + 2. ``averaged_inverted_cdf``: ``m = 0`` and + ``g = (1 + int(index - j > 0)) / 2`` + 3. ``closest_observation``: ``m = -1/2`` and + ``g = 1 - int((index == j) & (j%2 == 1))`` + + For backward compatibility with previous versions of NumPy, `quantile` + provides four additional discontinuous estimators. Like + ``method='linear'``, all have ``m = 1 - q`` so that ``j = q*(n-1) // 1``, + but ``g`` is defined as follows. + + - ``lower``: ``g = 0`` + - ``midpoint``: ``g = 0.5`` + - ``higher``: ``g = 1`` + - ``nearest``: ``g = (q*(n-1) % 1) > 0.5`` + + **Weighted quantiles:** + More formally, the quantile at probability level :math:`q` of a cumulative + distribution function :math:`F(y)=P(Y \\leq y)` with probability measure + :math:`P` is defined as any number :math:`x` that fulfills the + *coverage conditions* + + .. math:: P(Y < x) \\leq q \\quad\\text{and}\\quad P(Y \\leq x) \\geq q + + with random variable :math:`Y\\sim P`. + Sample quantiles, the result of `quantile`, provide nonparametric + estimation of the underlying population counterparts, represented by the + unknown :math:`F`, given a data vector `a` of length ``n``. + + Some of the estimators above arise when one considers :math:`F` as the + empirical distribution function of the data, i.e. + :math:`F(y) = \\frac{1}{n} \\sum_i 1_{a_i \\leq y}`. + Then, different methods correspond to different choices of :math:`x` that + fulfill the above coverage conditions. Methods that follow this approach + are ``inverted_cdf`` and ``averaged_inverted_cdf``. + + For weighted quantiles, the coverage conditions still hold. The + empirical cumulative distribution is simply replaced by its weighted + version, i.e. + :math:`P(Y \\leq t) = \\frac{1}{\\sum_i w_i} \\sum_i w_i 1_{x_i \\leq t}`. + Only ``method="inverted_cdf"`` supports weights. + + Examples + -------- + >>> import numpy as np + >>> a = np.array([[10, 7, 4], [3, 2, 1]]) + >>> a + array([[10, 7, 4], + [ 3, 2, 1]]) + >>> np.quantile(a, 0.5) + 3.5 + >>> np.quantile(a, 0.5, axis=0) + array([6.5, 4.5, 2.5]) + >>> np.quantile(a, 0.5, axis=1) + array([7., 2.]) + >>> np.quantile(a, 0.5, axis=1, keepdims=True) + array([[7.], + [2.]]) + >>> m = np.quantile(a, 0.5, axis=0) + >>> out = np.zeros_like(m) + >>> np.quantile(a, 0.5, axis=0, out=out) + array([6.5, 4.5, 2.5]) + >>> m + array([6.5, 4.5, 2.5]) + >>> b = a.copy() + >>> np.quantile(b, 0.5, axis=1, overwrite_input=True) + array([7., 2.]) + >>> assert not np.all(a == b) + + See also `numpy.percentile` for a visualization of most methods. + + References + ---------- + .. [1] R. J. Hyndman and Y. Fan, + "Sample quantiles in statistical packages," + The American Statistician, 50(4), pp. 361-365, 1996 + + """ + a = np.asanyarray(a) + if a.dtype.kind == "c": + raise TypeError("a must be an array of real numbers") + + weak_q = type(q) in (int, float) # use weak promotion for final result type + q = np.asanyarray(q) + + if not _quantile_is_valid(q): + raise ValueError("Quantiles must be in the range [0, 1]") + + if weights is not None: + if method != "inverted_cdf": + msg = ("Only method 'inverted_cdf' supports weights. " + f"Got: {method}.") + raise ValueError(msg) + if axis is not None: + axis = _nx.normalize_axis_tuple(axis, a.ndim, argname="axis") + weights = _weights_are_valid(weights=weights, a=a, axis=axis) + if np.any(weights < 0): + raise ValueError("Weights must be non-negative.") + + return _quantile_unchecked( + a, q, axis, out, overwrite_input, method, keepdims, weights, weak_q) + + +def _quantile_unchecked(a, + q, + axis=None, + out=None, + overwrite_input=False, + method="linear", + keepdims=False, + weights=None, + weak_q=False): + """Assumes that q is in [0, 1], and is an ndarray""" + return _ureduce(a, + func=_quantile_ureduce_func, + q=q, + weights=weights, + keepdims=keepdims, + axis=axis, + out=out, + overwrite_input=overwrite_input, + method=method, + weak_q=weak_q) + + +def _quantile_is_valid(q): + # avoid expensive reductions, relevant for arrays with < O(1000) elements + if q.ndim == 1 and q.size < 10: + for i in range(q.size): + if not (0.0 <= q[i] <= 1.0): + return False + elif not (q.min() >= 0 and q.max() <= 1): + return False + return True + + +def _compute_virtual_index(n, quantiles, alpha: float, beta: float): + """ + Compute the floating point indexes of an array for the linear + interpolation of quantiles. + n : array_like + The sample sizes. + quantiles : array_like + The quantiles values. + alpha : float + A constant used to correct the index computed. + beta : float + A constant used to correct the index computed. + + alpha and beta values depend on the chosen method + (see quantile documentation) + + Reference: + Hyndman&Fan paper "Sample Quantiles in Statistical Packages", + DOI: 10.1080/00031305.1996.10473566 + """ + return n * quantiles + ( + alpha + quantiles * (1 - alpha - beta) + ) - 1 + + +def _get_gamma(virtual_indexes, previous_indexes, method): + """ + Compute gamma (a.k.a 'm' or 'weight') for the linear interpolation + of quantiles. + + virtual_indexes : array_like + The indexes where the percentile is supposed to be found in the sorted + sample. + previous_indexes : array_like + The floor values of virtual_indexes. + method : dict + The interpolation method chosen, which may have a specific rule + modifying gamma. + + gamma is usually the fractional part of virtual_indexes but can be modified + by the interpolation method. + """ + gamma = np.asanyarray(virtual_indexes - previous_indexes) + gamma = method["fix_gamma"](gamma, virtual_indexes) + # Ensure both that we have an array, and that we keep the dtype + # (which may have been matched to the input array). + return np.asanyarray(gamma, dtype=virtual_indexes.dtype) + + +def _lerp(a, b, t, out=None): + """ + Compute the linear interpolation weighted by gamma on each point of + two same shape array. + + a : array_like + Left bound. + b : array_like + Right bound. + t : array_like + The interpolation weight. + out : array_like + Output array. + """ + diff_b_a = b - a + lerp_interpolation = add(a, diff_b_a * t, out=... if out is None else out) + subtract(b, diff_b_a * (1 - t), out=lerp_interpolation, where=t >= 0.5, + casting='unsafe', dtype=type(lerp_interpolation.dtype)) + if lerp_interpolation.ndim == 0 and out is None: + lerp_interpolation = lerp_interpolation[()] # unpack 0d arrays + return lerp_interpolation + + +def _get_gamma_mask(shape, default_value, conditioned_value, where): + out = np.full(shape, default_value) + np.copyto(out, conditioned_value, where=where, casting="unsafe") + return out + + +def _discrete_interpolation_to_boundaries(index, gamma_condition_fun): + previous = np.floor(index) + next = previous + 1 + gamma = index - previous + res = _get_gamma_mask(shape=index.shape, + default_value=next, + conditioned_value=previous, + where=gamma_condition_fun(gamma, index) + ).astype(np.intp) + # Some methods can lead to out-of-bound integers, clip them: + res[res < 0] = 0 + return res + + +def _closest_observation(n, quantiles): + # "choose the nearest even order statistic at g=0" (H&F (1996) pp. 362). + # Order is 1-based so for zero-based indexing round to nearest odd index. + gamma_fun = lambda gamma, index: (gamma == 0) & (np.floor(index) % 2 == 1) + return _discrete_interpolation_to_boundaries((n * quantiles) - 1 - 0.5, + gamma_fun) + + +def _inverted_cdf(n, quantiles): + gamma_fun = lambda gamma, _: (gamma == 0) + return _discrete_interpolation_to_boundaries((n * quantiles) - 1, + gamma_fun) + + +def _quantile_ureduce_func( + a: np.ndarray, + q: np.ndarray, + weights: np.ndarray | None, + axis: int | None = None, + out: np.ndarray | None = None, + overwrite_input: bool = False, + method: str = "linear", + weak_q: bool = False, +) -> np.ndarray: + if q.ndim > 2: + # The code below works fine for nd, but it might not have useful + # semantics. For now, keep the supported dimensions the same as it was + # before. + raise ValueError("q must be a scalar or 1d") + if overwrite_input: + if axis is None: + axis = 0 + arr = a.ravel() + wgt = None if weights is None else weights.ravel() + else: + arr = a + wgt = weights + elif axis is None: + axis = 0 + arr = a.flatten() + wgt = None if weights is None else weights.flatten() + else: + arr = a.copy() + wgt = weights + result = _quantile(arr, + quantiles=q, + axis=axis, + method=method, + out=out, + weights=wgt, + weak_q=weak_q) + return result + + +def _get_indexes(arr, virtual_indexes, valid_values_count): + """ + Get the valid indexes of arr neighbouring virtual_indexes. + Note + This is a companion function to linear interpolation of + Quantiles + + Returns + ------- + (previous_indexes, next_indexes): Tuple + A Tuple of virtual_indexes neighbouring indexes + """ + previous_indexes = floor(virtual_indexes, out=...) + next_indexes = add(previous_indexes, 1, out=...) + indexes_above_bounds = virtual_indexes >= valid_values_count - 1 + # When indexes is above max index, take the max value of the array + if indexes_above_bounds.any(): + previous_indexes[indexes_above_bounds] = -1 + next_indexes[indexes_above_bounds] = -1 + # When indexes is below min index, take the min value of the array + indexes_below_bounds = virtual_indexes < 0 + if indexes_below_bounds.any(): + previous_indexes[indexes_below_bounds] = 0 + next_indexes[indexes_below_bounds] = 0 + if np.issubdtype(arr.dtype, np.inexact): + # After the sort, slices having NaNs will have for last element a NaN + virtual_indexes_nans = np.isnan(virtual_indexes) + if virtual_indexes_nans.any(): + previous_indexes[virtual_indexes_nans] = -1 + next_indexes[virtual_indexes_nans] = -1 + previous_indexes = previous_indexes.astype(np.intp) + next_indexes = next_indexes.astype(np.intp) + return previous_indexes, next_indexes + + +def _quantile( + arr: "np.typing.ArrayLike", + quantiles: np.ndarray, + axis: int = -1, + method: str = "linear", + out: np.ndarray | None = None, + weights: "np.typing.ArrayLike | None" = None, + weak_q: bool = False, +) -> np.ndarray: + """ + Private function that doesn't support extended axis or keepdims. + These methods are extended to this function using _ureduce + See nanpercentile for parameter usage + It computes the quantiles of the array for the given axis. + A linear interpolation is performed based on the `method`. + + By default, the method is "linear" where alpha == beta == 1 which + performs the 7th method of Hyndman&Fan. + With "median_unbiased" we get alpha == beta == 1/3 + thus the 8th method of Hyndman&Fan. + """ + # --- Setup + arr = np.asanyarray(arr) + values_count = arr.shape[axis] + # The dimensions of `q` are prepended to the output shape, so we need the + # axis being sampled from `arr` to be last. + if axis != 0: # But moveaxis is slow, so only call it if necessary. + arr = np.moveaxis(arr, axis, destination=0) + supports_nans = ( + np.issubdtype(arr.dtype, np.inexact) or arr.dtype.kind in 'Mm' + ) + + if weights is None: + # --- Computation of indexes + # Index where to find the value in the sorted array. + # Virtual because it is a floating point value, not a valid index. + # The nearest neighbours are used for interpolation + try: + method_props = _QuantileMethods[method] + except KeyError: + raise ValueError( + f"{method!r} is not a valid method. Use one of: " + f"{_QuantileMethods.keys()}") from None + virtual_indexes = method_props["get_virtual_index"](values_count, + quantiles) + virtual_indexes = np.asanyarray(virtual_indexes) + + if method_props["fix_gamma"] is None: + supports_integers = True + else: + int_virtual_indices = np.issubdtype(virtual_indexes.dtype, + np.integer) + supports_integers = method == 'linear' and int_virtual_indices + + if supports_integers: + # No interpolation needed, take the points along axis + if supports_nans: + # may contain nan, which would sort to the end + arr.partition( + concatenate((virtual_indexes.ravel(), [-1])), axis=0, + ) + slices_having_nans = np.isnan(arr[-1, ...]) + else: + # cannot contain nan + arr.partition(virtual_indexes.ravel(), axis=0) + slices_having_nans = np.array(False, dtype=bool) + result = take(arr, virtual_indexes, axis=0, out=out) + else: + previous_indexes, next_indexes = _get_indexes(arr, + virtual_indexes, + values_count) + # --- Sorting + arr.partition( + np.unique(np.concatenate(([0, -1], + previous_indexes.ravel(), + next_indexes.ravel(), + ))), + axis=0) + if supports_nans: + slices_having_nans = np.isnan(arr[-1, ...]) + else: + slices_having_nans = None + # --- Get values from indexes + previous = arr[previous_indexes] + next = arr[next_indexes] + # --- Linear interpolation + gamma = _get_gamma(virtual_indexes, previous_indexes, + method_props) + if weak_q: + gamma = float(gamma) + else: + result_shape = virtual_indexes.shape + (1,) * (arr.ndim - 1) + gamma = gamma.reshape(result_shape) + result = _lerp(previous, + next, + gamma, + out=out) + else: + # Weighted case + # This implements method="inverted_cdf", the only supported weighted + # method, which needs to sort anyway. + weights = np.asanyarray(weights) + if axis != 0: + weights = np.moveaxis(weights, axis, destination=0) + index_array = np.argsort(arr, axis=0) + + # arr = arr[index_array, ...] # but this adds trailing dimensions of + # 1. + arr = np.take_along_axis(arr, index_array, axis=0) + if weights.shape == arr.shape: + weights = np.take_along_axis(weights, index_array, axis=0) + else: + # weights is 1d + weights = weights.reshape(-1)[index_array, ...] + + if supports_nans: + # may contain nan, which would sort to the end + slices_having_nans = np.isnan(arr[-1, ...]) + else: + # cannot contain nan + slices_having_nans = np.array(False, dtype=bool) + + # We use the weights to calculate the empirical cumulative + # distribution function cdf + cdf = weights.cumsum(axis=0, dtype=np.float64) + cdf /= cdf[-1, ...] # normalization to 1 + if np.isnan(cdf[-1]).any(): + # Above calculations should normally warn for the zero/inf case. + raise ValueError("Weights included NaN, inf or were all zero.") + # Search index i such that + # sum(weights[j], j=0..i-1) < quantile <= sum(weights[j], j=0..i) + # is then equivalent to + # cdf[i-1] < quantile <= cdf[i] + # Unfortunately, searchsorted only accepts 1-d arrays as first + # argument, so we will need to iterate over dimensions. + + # Without the following cast, searchsorted can return surprising + # results, e.g. + # np.searchsorted(np.array([0.2, 0.4, 0.6, 0.8, 1.]), + # np.array(0.4, dtype=np.float32), side="left") + # returns 2 instead of 1 because 0.4 is not binary representable. + if quantiles.dtype.kind == "f": + cdf = cdf.astype(quantiles.dtype) + # Weights must be non-negative, so we might have zero weights at the + # beginning leading to some leading zeros in cdf. The call to + # np.searchsorted for quantiles=0 will then pick the first element, + # but should pick the first one larger than zero. We + # therefore simply set 0 values in cdf to -1. + if np.any(cdf[0, ...] == 0): + cdf[cdf == 0] = -1 + + def find_cdf_1d(arr, cdf): + indices = np.searchsorted(cdf, quantiles, side="left") + # We might have reached the maximum with i = len(arr), e.g. for + # quantiles = 1, and need to cut it to len(arr) - 1. + indices = minimum(indices, values_count - 1) + result = take(arr, indices, axis=0) + return result + + r_shape = arr.shape[1:] + if quantiles.ndim > 0: + r_shape = quantiles.shape + r_shape + if out is None: + result = np.empty_like(arr, shape=r_shape) + else: + if out.shape != r_shape: + msg = (f"Wrong shape of argument 'out', shape={r_shape} is " + f"required; got shape={out.shape}.") + raise ValueError(msg) + result = out + + # See apply_along_axis, which we do for axis=0. Note that Ni = (,) + # always, so we remove it here. + Nk = arr.shape[1:] + for kk in np.ndindex(Nk): + result[(...,) + kk] = find_cdf_1d( + arr[np.s_[:, ] + kk], cdf[np.s_[:, ] + kk] + ) + + # Make result the same as in unweighted inverted_cdf. + if result.shape == () and result.dtype == np.dtype("O"): + result = result.item() + + if np.any(slices_having_nans): + if result.ndim == 0 and out is None: + # can't write to a scalar, but indexing will be correct + result = arr[-1] + else: + np.copyto(result, arr[-1, ...], where=slices_having_nans) + return result + + +def _trapezoid_dispatcher(y, x=None, dx=None, axis=None): + return (y, x) + + +@array_function_dispatch(_trapezoid_dispatcher) +def trapezoid(y, x=None, dx=1.0, axis=-1): + r""" + Integrate along the given axis using the composite trapezoidal rule. + + If `x` is provided, the integration happens in sequence along its + elements - they are not sorted. + + Integrate `y` (`x`) along each 1d slice on the given axis, compute + :math:`\int y(x) dx`. + When `x` is specified, this integrates along the parametric curve, + computing :math:`\int_t y(t) dt = + \int_t y(t) \left.\frac{dx}{dt}\right|_{x=x(t)} dt`. + + .. versionadded:: 2.0.0 + + Parameters + ---------- + y : array_like + Input array to integrate. + x : array_like, optional + The sample points corresponding to the `y` values. If `x` is None, + the sample points are assumed to be evenly spaced `dx` apart. The + default is None. + dx : scalar, optional + The spacing between sample points when `x` is None. The default is 1. + axis : int, optional + The axis along which to integrate. + + Returns + ------- + trapezoid : float or ndarray + Definite integral of `y` = n-dimensional array as approximated along + a single axis by the trapezoidal rule. If `y` is a 1-dimensional array, + then the result is a float. If `n` is greater than 1, then the result + is an `n`-1 dimensional array. + + See Also + -------- + sum, cumsum + + Notes + ----- + Image [2]_ illustrates trapezoidal rule -- y-axis locations of points + will be taken from `y` array, by default x-axis distances between + points will be 1.0, alternatively they can be provided with `x` array + or with `dx` scalar. Return value will be equal to combined area under + the red lines. + + + References + ---------- + .. [1] Wikipedia page: https://en.wikipedia.org/wiki/Trapezoidal_rule + + .. [2] Illustration image: + https://en.wikipedia.org/wiki/File:Composite_trapezoidal_rule_illustration.png + + Examples + -------- + >>> import numpy as np + + Use the trapezoidal rule on evenly spaced points: + + >>> np.trapezoid([1, 2, 3]) + 4.0 + + The spacing between sample points can be selected by either the + ``x`` or ``dx`` arguments: + + >>> np.trapezoid([1, 2, 3], x=[4, 6, 8]) + 8.0 + >>> np.trapezoid([1, 2, 3], dx=2) + 8.0 + + Using a decreasing ``x`` corresponds to integrating in reverse: + + >>> np.trapezoid([1, 2, 3], x=[8, 6, 4]) + -8.0 + + More generally ``x`` is used to integrate along a parametric curve. We can + estimate the integral :math:`\int_0^1 x^2 = 1/3` using: + + >>> x = np.linspace(0, 1, num=50) + >>> y = x**2 + >>> np.trapezoid(y, x) + 0.33340274885464394 + + Or estimate the area of a circle, noting we repeat the sample which closes + the curve: + + >>> theta = np.linspace(0, 2 * np.pi, num=1000, endpoint=True) + >>> np.trapezoid(np.cos(theta), x=np.sin(theta)) + 3.141571941375841 + + ``np.trapezoid`` can be applied along a specified axis to do multiple + computations in one call: + + >>> a = np.arange(6).reshape(2, 3) + >>> a + array([[0, 1, 2], + [3, 4, 5]]) + >>> np.trapezoid(a, axis=0) + array([1.5, 2.5, 3.5]) + >>> np.trapezoid(a, axis=1) + array([2., 8.]) + """ + + y = asanyarray(y) + if x is None: + d = dx + else: + x = asanyarray(x) + if x.ndim == 1: + d = diff(x) + # reshape to correct shape + shape = [1] * y.ndim + shape[axis] = d.shape[0] + d = d.reshape(shape) + else: + d = diff(x, axis=axis) + nd = y.ndim + slice1 = [slice(None)] * nd + slice2 = [slice(None)] * nd + slice1[axis] = slice(1, None) + slice2[axis] = slice(None, -1) + try: + ret = (d * (y[tuple(slice1)] + y[tuple(slice2)]) / 2.0).sum(axis) + except ValueError: + # Operations didn't work, cast to ndarray + d = np.asarray(d) + y = np.asarray(y) + ret = add.reduce(d * (y[tuple(slice1)] + y[tuple(slice2)]) / 2.0, axis) + return ret + + +def _meshgrid_dispatcher(*xi, copy=None, sparse=None, indexing=None): + return xi + + +# Based on scitools meshgrid +@array_function_dispatch(_meshgrid_dispatcher) +def meshgrid(*xi, copy=True, sparse=False, indexing='xy'): + """ + Return a tuple of coordinate matrices from coordinate vectors. + + Make N-D coordinate arrays for vectorized evaluations of + N-D scalar/vector fields over N-D grids, given + one-dimensional coordinate arrays x1, x2,..., xn. + + Parameters + ---------- + x1, x2,..., xn : array_like + 1-D arrays representing the coordinates of a grid. + indexing : {'xy', 'ij'}, optional + Cartesian ('xy', default) or matrix ('ij') indexing of output. + See Notes for more details. + sparse : bool, optional + If True the shape of the returned coordinate array for dimension *i* + is reduced from ``(N1, ..., Ni, ... Nn)`` to + ``(1, ..., 1, Ni, 1, ..., 1)``. These sparse coordinate grids are + intended to be used with :ref:`basics.broadcasting`. When all + coordinates are used in an expression, broadcasting still leads to a + fully-dimensonal result array. + + Default is False. + + copy : bool, optional + If False, a view into the original arrays are returned in order to + conserve memory. Default is True. Please note that + ``sparse=False, copy=False`` will likely return non-contiguous + arrays. Furthermore, more than one element of a broadcast array + may refer to a single memory location. If you need to write to the + arrays, make copies first. + + Returns + ------- + X1, X2,..., XN : tuple of ndarrays + For vectors `x1`, `x2`,..., `xn` with lengths ``Ni=len(xi)``, + returns ``(N1, N2, N3,..., Nn)`` shaped arrays if indexing='ij' + or ``(N2, N1, N3,..., Nn)`` shaped arrays if indexing='xy' + with the elements of `xi` repeated to fill the matrix along + the first dimension for `x1`, the second for `x2` and so on. + + Notes + ----- + This function supports both indexing conventions through the indexing + keyword argument. Giving the string 'ij' returns a meshgrid with + matrix indexing, while 'xy' returns a meshgrid with Cartesian indexing. + In the 2-D case with inputs of length M and N, the outputs are of shape + (N, M) for 'xy' indexing and (M, N) for 'ij' indexing. In the 3-D case + with inputs of length M, N and P, outputs are of shape (N, M, P) for + 'xy' indexing and (M, N, P) for 'ij' indexing. The difference is + illustrated by the following code snippet:: + + xv, yv = np.meshgrid(x, y, indexing='ij') + for i in range(nx): + for j in range(ny): + # treat xv[i,j], yv[i,j] + + xv, yv = np.meshgrid(x, y, indexing='xy') + for i in range(nx): + for j in range(ny): + # treat xv[j,i], yv[j,i] + + In the 1-D and 0-D case, the indexing and sparse keywords have no effect. + + See Also + -------- + mgrid : Construct a multi-dimensional "meshgrid" using indexing notation. + ogrid : Construct an open multi-dimensional "meshgrid" using indexing + notation. + :ref:`how-to-index` + + Examples + -------- + >>> import numpy as np + >>> nx, ny = (3, 2) + >>> x = np.linspace(0, 1, nx) + >>> y = np.linspace(0, 1, ny) + >>> xv, yv = np.meshgrid(x, y) + >>> xv + array([[0. , 0.5, 1. ], + [0. , 0.5, 1. ]]) + >>> yv + array([[0., 0., 0.], + [1., 1., 1.]]) + + The result of `meshgrid` is a coordinate grid: + + >>> import matplotlib.pyplot as plt + >>> plt.plot(xv, yv, marker='o', color='k', linestyle='none') + >>> plt.show() + + You can create sparse output arrays to save memory and computation time. + + >>> xv, yv = np.meshgrid(x, y, sparse=True) + >>> xv + array([[0. , 0.5, 1. ]]) + >>> yv + array([[0.], + [1.]]) + + `meshgrid` is very useful to evaluate functions on a grid. If the + function depends on all coordinates, both dense and sparse outputs can be + used. + + >>> x = np.linspace(-5, 5, 101) + >>> y = np.linspace(-5, 5, 101) + >>> # full coordinate arrays + >>> xx, yy = np.meshgrid(x, y) + >>> zz = np.sqrt(xx**2 + yy**2) + >>> xx.shape, yy.shape, zz.shape + ((101, 101), (101, 101), (101, 101)) + >>> # sparse coordinate arrays + >>> xs, ys = np.meshgrid(x, y, sparse=True) + >>> zs = np.sqrt(xs**2 + ys**2) + >>> xs.shape, ys.shape, zs.shape + ((1, 101), (101, 1), (101, 101)) + >>> np.array_equal(zz, zs) + True + + >>> h = plt.contourf(x, y, zs) + >>> plt.axis('scaled') + >>> plt.colorbar() + >>> plt.show() + """ + ndim = len(xi) + + if indexing not in ['xy', 'ij']: + raise ValueError( + "Valid values for `indexing` are 'xy' and 'ij'.") + + s0 = (1,) * ndim + output = [np.asanyarray(x).reshape(s0[:i] + (-1,) + s0[i + 1:]) + for i, x in enumerate(xi)] + + if indexing == 'xy' and ndim > 1: + # switch first and second axis + output[0].shape = (1, -1) + s0[2:] + output[1].shape = (-1, 1) + s0[2:] + + if not sparse: + # Return the full N-D matrix (not only the 1-D vector) + output = np.broadcast_arrays(*output, subok=True) + + if copy: + output = tuple(x.copy() for x in output) + + return output + + +def _delete_dispatcher(arr, obj, axis=None): + return (arr, obj) + + +@array_function_dispatch(_delete_dispatcher) +def delete(arr, obj, axis=None): + """ + Return a new array with sub-arrays along an axis deleted. For a one + dimensional array, this returns those entries not returned by + `arr[obj]`. + + Parameters + ---------- + arr : array_like + Input array. + obj : slice, int, array-like of ints or bools + Indicate indices of sub-arrays to remove along the specified axis. + + .. versionchanged:: 1.19.0 + Boolean indices are now treated as a mask of elements to remove, + rather than being cast to the integers 0 and 1. + + axis : int, optional + The axis along which to delete the subarray defined by `obj`. + If `axis` is None, `obj` is applied to the flattened array. + + Returns + ------- + out : ndarray + A copy of `arr` with the elements specified by `obj` removed. Note + that `delete` does not occur in-place. If `axis` is None, `out` is + a flattened array. + + See Also + -------- + insert : Insert elements into an array. + append : Append elements at the end of an array. + + Notes + ----- + Often it is preferable to use a boolean mask. For example: + + >>> arr = np.arange(12) + 1 + >>> mask = np.ones(len(arr), dtype=bool) + >>> mask[[0,2,4]] = False + >>> result = arr[mask,...] + + Is equivalent to ``np.delete(arr, [0,2,4], axis=0)``, but allows further + use of `mask`. + + Examples + -------- + >>> import numpy as np + >>> arr = np.array([[1,2,3,4], [5,6,7,8], [9,10,11,12]]) + >>> arr + array([[ 1, 2, 3, 4], + [ 5, 6, 7, 8], + [ 9, 10, 11, 12]]) + >>> np.delete(arr, 1, 0) + array([[ 1, 2, 3, 4], + [ 9, 10, 11, 12]]) + + >>> np.delete(arr, np.s_[::2], 1) + array([[ 2, 4], + [ 6, 8], + [10, 12]]) + >>> np.delete(arr, [1,3,5], None) + array([ 1, 3, 5, 7, 8, 9, 10, 11, 12]) + + """ + conv = _array_converter(arr) + arr, = conv.as_arrays(subok=False) + + ndim = arr.ndim + arrorder = 'F' if arr.flags.fnc else 'C' + if axis is None: + if ndim != 1: + arr = arr.ravel() + # needed for np.matrix, which is still not 1d after being ravelled + ndim = arr.ndim + axis = ndim - 1 + else: + axis = normalize_axis_index(axis, ndim) + + slobj = [slice(None)] * ndim + N = arr.shape[axis] + newshape = list(arr.shape) + + if isinstance(obj, slice): + start, stop, step = obj.indices(N) + xr = range(start, stop, step) + numtodel = len(xr) + + if numtodel <= 0: + return conv.wrap(arr.copy(order=arrorder), to_scalar=False) + + # Invert if step is negative: + if step < 0: + step = -step + start = xr[-1] + stop = xr[0] + 1 + + newshape[axis] -= numtodel + new = empty(newshape, arr.dtype, arrorder) + # copy initial chunk + if start == 0: + pass + else: + slobj[axis] = slice(None, start) + new[tuple(slobj)] = arr[tuple(slobj)] + # copy end chunk + if stop == N: + pass + else: + slobj[axis] = slice(stop - numtodel, None) + slobj2 = [slice(None)] * ndim + slobj2[axis] = slice(stop, None) + new[tuple(slobj)] = arr[tuple(slobj2)] + # copy middle pieces + if step == 1: + pass + else: # use array indexing. + keep = ones(stop - start, dtype=bool) + keep[:stop - start:step] = False + slobj[axis] = slice(start, stop - numtodel) + slobj2 = [slice(None)] * ndim + slobj2[axis] = slice(start, stop) + arr = arr[tuple(slobj2)] + slobj2[axis] = keep + new[tuple(slobj)] = arr[tuple(slobj2)] + + return conv.wrap(new, to_scalar=False) + + if isinstance(obj, (int, integer)) and not isinstance(obj, bool): + single_value = True + else: + single_value = False + _obj = obj + obj = np.asarray(obj) + # `size == 0` to allow empty lists similar to indexing, but (as there) + # is really too generic: + if obj.size == 0 and not isinstance(_obj, np.ndarray): + obj = obj.astype(intp) + elif obj.size == 1 and obj.dtype.kind in "ui": + # For a size 1 integer array we can use the single-value path + # (most dtypes, except boolean, should just fail later). + obj = obj.item() + single_value = True + + if single_value: + # optimization for a single value + if (obj < -N or obj >= N): + raise IndexError( + f"index {obj} is out of bounds for axis {axis} with " + f"size {N}") + if (obj < 0): + obj += N + newshape[axis] -= 1 + new = empty(newshape, arr.dtype, arrorder) + slobj[axis] = slice(None, obj) + new[tuple(slobj)] = arr[tuple(slobj)] + slobj[axis] = slice(obj, None) + slobj2 = [slice(None)] * ndim + slobj2[axis] = slice(obj + 1, None) + new[tuple(slobj)] = arr[tuple(slobj2)] + else: + if obj.dtype == bool: + if obj.shape != (N,): + raise ValueError('boolean array argument obj to delete ' + 'must be one dimensional and match the axis ' + f'length of {N}') + + # optimization, the other branch is slower + keep = ~obj + else: + keep = ones(N, dtype=bool) + keep[obj,] = False + + slobj[axis] = keep + new = arr[tuple(slobj)] + + return conv.wrap(new, to_scalar=False) + + +def _insert_dispatcher(arr, obj, values, axis=None): + return (arr, obj, values) + + +@array_function_dispatch(_insert_dispatcher) +def insert(arr, obj, values, axis=None): + """ + Insert values along the given axis before the given indices. + + Parameters + ---------- + arr : array_like + Input array. + obj : slice, int, array-like of ints or bools + Object that defines the index or indices before which `values` is + inserted. + + .. versionchanged:: 2.1.2 + Boolean indices are now treated as a mask of elements to insert, + rather than being cast to the integers 0 and 1. + + Support for multiple insertions when `obj` is a single scalar or a + sequence with one element (similar to calling insert multiple + times). + values : array_like + Values to insert into `arr`. If the type of `values` is different + from that of `arr`, `values` is converted to the type of `arr`. + `values` should be shaped so that ``arr[...,obj,...] = values`` + is legal. + axis : int, optional + Axis along which to insert `values`. If `axis` is None then `arr` + is flattened first. + + Returns + ------- + out : ndarray + A copy of `arr` with `values` inserted. Note that `insert` + does not occur in-place: a new array is returned. If + `axis` is None, `out` is a flattened array. + + See Also + -------- + append : Append elements at the end of an array. + concatenate : Join a sequence of arrays along an existing axis. + delete : Delete elements from an array. + + Notes + ----- + Note that for higher dimensional inserts ``obj=0`` behaves very different + from ``obj=[0]`` just like ``arr[:,0,:] = values`` is different from + ``arr[:,[0],:] = values``. This is because of the difference between basic + and advanced :ref:`indexing `. + + Examples + -------- + >>> import numpy as np + >>> a = np.arange(6).reshape(3, 2) + >>> a + array([[0, 1], + [2, 3], + [4, 5]]) + >>> np.insert(a, 1, 6) + array([0, 6, 1, 2, 3, 4, 5]) + >>> np.insert(a, 1, 6, axis=1) + array([[0, 6, 1], + [2, 6, 3], + [4, 6, 5]]) + + Difference between sequence and scalars, + showing how ``obj=[1]`` behaves different from ``obj=1``: + + >>> np.insert(a, [1], [[7],[8],[9]], axis=1) + array([[0, 7, 1], + [2, 8, 3], + [4, 9, 5]]) + >>> np.insert(a, 1, [[7],[8],[9]], axis=1) + array([[0, 7, 8, 9, 1], + [2, 7, 8, 9, 3], + [4, 7, 8, 9, 5]]) + >>> np.array_equal(np.insert(a, 1, [7, 8, 9], axis=1), + ... np.insert(a, [1], [[7],[8],[9]], axis=1)) + True + + >>> b = a.flatten() + >>> b + array([0, 1, 2, 3, 4, 5]) + >>> np.insert(b, [2, 2], [6, 7]) + array([0, 1, 6, 7, 2, 3, 4, 5]) + + >>> np.insert(b, slice(2, 4), [7, 8]) + array([0, 1, 7, 2, 8, 3, 4, 5]) + + >>> np.insert(b, [2, 2], [7.13, False]) # type casting + array([0, 1, 7, 0, 2, 3, 4, 5]) + + >>> x = np.arange(8).reshape(2, 4) + >>> idx = (1, 3) + >>> np.insert(x, idx, 999, axis=1) + array([[ 0, 999, 1, 2, 999, 3], + [ 4, 999, 5, 6, 999, 7]]) + + """ + conv = _array_converter(arr) + arr, = conv.as_arrays(subok=False) + + ndim = arr.ndim + arrorder = 'F' if arr.flags.fnc else 'C' + if axis is None: + if ndim != 1: + arr = arr.ravel() + # needed for np.matrix, which is still not 1d after being ravelled + ndim = arr.ndim + axis = ndim - 1 + else: + axis = normalize_axis_index(axis, ndim) + slobj = [slice(None)] * ndim + N = arr.shape[axis] + newshape = list(arr.shape) + + if isinstance(obj, slice): + # turn it into a range object + indices = arange(*obj.indices(N), dtype=intp) + else: + # need to copy obj, because indices will be changed in-place + indices = np.array(obj) + if indices.dtype == bool: + if obj.ndim != 1: + raise ValueError('boolean array argument obj to insert ' + 'must be one dimensional') + indices = np.flatnonzero(obj) + elif indices.ndim > 1: + raise ValueError( + "index array argument obj to insert must be one dimensional " + "or scalar") + if indices.size == 1: + index = indices.item() + if index < -N or index > N: + raise IndexError(f"index {obj} is out of bounds for axis {axis} " + f"with size {N}") + if (index < 0): + index += N + + # There are some object array corner cases here, but we cannot avoid + # that: + values = array(values, copy=None, ndmin=arr.ndim, dtype=arr.dtype) + if indices.ndim == 0: + # broadcasting is very different here, since a[:,0,:] = ... behaves + # very different from a[:,[0],:] = ...! This changes values so that + # it works likes the second case. (here a[:,0:1,:]) + values = np.moveaxis(values, 0, axis) + numnew = values.shape[axis] + newshape[axis] += numnew + new = empty(newshape, arr.dtype, arrorder) + slobj[axis] = slice(None, index) + new[tuple(slobj)] = arr[tuple(slobj)] + slobj[axis] = slice(index, index + numnew) + new[tuple(slobj)] = values + slobj[axis] = slice(index + numnew, None) + slobj2 = [slice(None)] * ndim + slobj2[axis] = slice(index, None) + new[tuple(slobj)] = arr[tuple(slobj2)] + + return conv.wrap(new, to_scalar=False) + + elif indices.size == 0 and not isinstance(obj, np.ndarray): + # Can safely cast the empty list to intp + indices = indices.astype(intp) + + indices[indices < 0] += N + + numnew = len(indices) + order = indices.argsort(kind='mergesort') # stable sort + indices[order] += np.arange(numnew) + + newshape[axis] += numnew + old_mask = ones(newshape[axis], dtype=bool) + old_mask[indices] = False + + new = empty(newshape, arr.dtype, arrorder) + slobj2 = [slice(None)] * ndim + slobj[axis] = indices + slobj2[axis] = old_mask + new[tuple(slobj)] = values + new[tuple(slobj2)] = arr + + return conv.wrap(new, to_scalar=False) + + +def _append_dispatcher(arr, values, axis=None): + return (arr, values) + + +@array_function_dispatch(_append_dispatcher) +def append(arr, values, axis=None): + """ + Append values to the end of an array. + + Parameters + ---------- + arr : array_like + Values are appended to a copy of this array. + values : array_like + These values are appended to a copy of `arr`. It must be of the + correct shape (the same shape as `arr`, excluding `axis`). If + `axis` is not specified, `values` can be any shape and will be + flattened before use. + axis : int, optional + The axis along which `values` are appended. If `axis` is not + given, both `arr` and `values` are flattened before use. + + Returns + ------- + append : ndarray + A copy of `arr` with `values` appended to `axis`. Note that + `append` does not occur in-place: a new array is allocated and + filled. If `axis` is None, `out` is a flattened array. + + See Also + -------- + insert : Insert elements into an array. + delete : Delete elements from an array. + + Examples + -------- + >>> import numpy as np + >>> np.append([1, 2, 3], [[4, 5, 6], [7, 8, 9]]) + array([1, 2, 3, ..., 7, 8, 9]) + + When `axis` is specified, `values` must have the correct shape. + + >>> np.append([[1, 2, 3], [4, 5, 6]], [[7, 8, 9]], axis=0) + array([[1, 2, 3], + [4, 5, 6], + [7, 8, 9]]) + + >>> np.append([[1, 2, 3], [4, 5, 6]], [7, 8, 9], axis=0) + Traceback (most recent call last): + ... + ValueError: all the input arrays must have same number of dimensions, but + the array at index 0 has 2 dimension(s) and the array at index 1 has 1 + dimension(s) + + >>> a = np.array([1, 2], dtype=int) + >>> c = np.append(a, []) + >>> c + array([1., 2.]) + >>> c.dtype + float64 + + Default dtype for empty ndarrays is `float64` thus making the output of dtype + `float64` when appended with dtype `int64` + + """ + arr = asanyarray(arr) + if axis is None: + if arr.ndim != 1: + arr = arr.ravel() + values = ravel(values) + axis = arr.ndim - 1 + return concatenate((arr, values), axis=axis) + + +def _digitize_dispatcher(x, bins, right=None): + return (x, bins) + + +@array_function_dispatch(_digitize_dispatcher) +def digitize(x, bins, right=False): + """ + Return the indices of the bins to which each value in input array belongs. + + ========= ============= ============================ + `right` order of bins returned index `i` satisfies + ========= ============= ============================ + ``False`` increasing ``bins[i-1] <= x < bins[i]`` + ``True`` increasing ``bins[i-1] < x <= bins[i]`` + ``False`` decreasing ``bins[i-1] > x >= bins[i]`` + ``True`` decreasing ``bins[i-1] >= x > bins[i]`` + ========= ============= ============================ + + If values in `x` are beyond the bounds of `bins`, 0 or ``len(bins)`` is + returned as appropriate. + + Parameters + ---------- + x : array_like + Input array to be binned. Prior to NumPy 1.10.0, this array had to + be 1-dimensional, but can now have any shape. + bins : array_like + Array of bins. It has to be 1-dimensional and monotonic. + right : bool, optional + Indicating whether the intervals include the right or the left bin + edge. Default behavior is (right==False) indicating that the interval + does not include the right edge. The left bin end is open in this + case, i.e., bins[i-1] <= x < bins[i] is the default behavior for + monotonically increasing bins. + + Returns + ------- + indices : ndarray of ints + Output array of indices, of same shape as `x`. + + Raises + ------ + ValueError + If `bins` is not monotonic. + TypeError + If the type of the input is complex. + + See Also + -------- + bincount, histogram, unique, searchsorted + + Notes + ----- + If values in `x` are such that they fall outside the bin range, + attempting to index `bins` with the indices that `digitize` returns + will result in an IndexError. + + .. versionadded:: 1.10.0 + + `numpy.digitize` is implemented in terms of `numpy.searchsorted`. + This means that a binary search is used to bin the values, which scales + much better for larger number of bins than the previous linear search. + It also removes the requirement for the input array to be 1-dimensional. + + For monotonically *increasing* `bins`, the following are equivalent:: + + np.digitize(x, bins, right=True) + np.searchsorted(bins, x, side='left') + + Note that as the order of the arguments are reversed, the side must be too. + The `searchsorted` call is marginally faster, as it does not do any + monotonicity checks. Perhaps more importantly, it supports all dtypes. + + Examples + -------- + >>> import numpy as np + >>> x = np.array([0.2, 6.4, 3.0, 1.6]) + >>> bins = np.array([0.0, 1.0, 2.5, 4.0, 10.0]) + >>> inds = np.digitize(x, bins) + >>> inds + array([1, 4, 3, 2]) + >>> for n in range(x.size): + ... print(bins[inds[n]-1], "<=", x[n], "<", bins[inds[n]]) + ... + 0.0 <= 0.2 < 1.0 + 4.0 <= 6.4 < 10.0 + 2.5 <= 3.0 < 4.0 + 1.0 <= 1.6 < 2.5 + + >>> x = np.array([1.2, 10.0, 12.4, 15.5, 20.]) + >>> bins = np.array([0, 5, 10, 15, 20]) + >>> np.digitize(x,bins,right=True) + array([1, 2, 3, 4, 4]) + >>> np.digitize(x,bins,right=False) + array([1, 3, 3, 4, 5]) + """ + x = _nx.asarray(x) + bins = _nx.asarray(bins) + + # here for compatibility, searchsorted below is happy to take this + if np.issubdtype(x.dtype, _nx.complexfloating): + raise TypeError("x may not be complex") + + mono = _monotonicity(bins) + if mono == 0: + raise ValueError("bins must be monotonically increasing or decreasing") + + # this is backwards because the arguments below are swapped + side = 'left' if right else 'right' + if mono == -1: + # reverse the bins, and invert the results + return len(bins) - _nx.searchsorted(bins[::-1], x, side=side) + else: + return _nx.searchsorted(bins, x, side=side)