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import numpy |
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import cupy |
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from cupy import _core |
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def place(arr, mask, vals): |
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"""Change elements of an array based on conditional and input values. |
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This function uses the first N elements of `vals`, where N is the number |
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of true values in `mask`. |
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Args: |
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arr (cupy.ndarray): Array to put data into. |
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mask (array-like): Boolean mask array. Must have the same size as `a`. |
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vals (array-like): Values to put into `a`. Only the first |
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N elements are used, where N is the number of True values in |
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`mask`. If `vals` is smaller than N, it will be repeated, and if |
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elements of `a` are to be masked, this sequence must be non-empty. |
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Examples |
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-------- |
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>>> arr = np.arange(6).reshape(2, 3) |
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>>> np.place(arr, arr>2, [44, 55]) |
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>>> arr |
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array([[ 0, 1, 2], |
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[44, 55, 44]]) |
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.. warning:: |
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This function may synchronize the device. |
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.. seealso:: :func:`numpy.place` |
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""" |
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mask = cupy.asarray(mask) |
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if arr.size != mask.size: |
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raise ValueError('Mask and data must be the same size.') |
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vals = cupy.asarray(vals) |
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mask_indices = mask.ravel().nonzero()[0] |
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if mask_indices.size == 0: |
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return |
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if vals.size == 0: |
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raise ValueError('Cannot insert from an empty array.') |
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arr.put(mask_indices, vals, mode='wrap') |
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def put(a, ind, v, mode='wrap'): |
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"""Replaces specified elements of an array with given values. |
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Args: |
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a (cupy.ndarray): Target array. |
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ind (array-like): Target indices, interpreted as integers. |
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v (array-like): Values to place in `a` at target indices. |
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If `v` is shorter than `ind` it will be repeated as necessary. |
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mode (str): How out-of-bounds indices will behave. Its value must be |
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either `'raise'`, `'wrap'` or `'clip'`. Otherwise, |
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:class:`TypeError` is raised. |
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.. note:: |
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Default `mode` is set to `'wrap'` to avoid unintended performance drop. |
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If you need NumPy's behavior, please pass `mode='raise'` manually. |
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.. seealso:: :func:`numpy.put` |
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""" |
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a.put(ind, v, mode=mode) |
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_putmask_kernel = _core.ElementwiseKernel( |
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'Q mask, raw S values, uint64 len_vals', 'T out', |
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''' |
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if (mask) out = (T) values[i % len_vals]; |
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''', |
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'cupy_putmask_kernel' |
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) |
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def putmask(a, mask, values): |
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""" |
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Changes elements of an array inplace, based on a conditional mask and |
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input values. |
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Sets ``a.flat[n] = values[n]`` for each n where ``mask.flat[n]==True``. |
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If `values` is not the same size as `a` and `mask` then it will repeat. |
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Args: |
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a (cupy.ndarray): Target array. |
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mask (cupy.ndarray): Boolean mask array. It has to be |
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the same shape as `a`. |
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values (cupy.ndarray or scalar): Values to put into `a` where `mask` |
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is True. If `values` is smaller than `a`, then it will be |
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repeated. |
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Examples |
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-------- |
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>>> x = cupy.arange(6).reshape(2, 3) |
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>>> cupy.putmask(x, x>2, x**2) |
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>>> x |
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array([[ 0, 1, 2], |
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[ 9, 16, 25]]) |
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If `values` is smaller than `a` it is repeated: |
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>>> x = cupy.arange(6) |
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>>> cupy.putmask(x, x>2, cupy.array([-33, -44])) |
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>>> x |
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array([ 0, 1, 2, -44, -33, -44]) |
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.. seealso:: :func:`numpy.putmask` |
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""" |
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if not isinstance(a, cupy.ndarray): |
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raise TypeError('`a` should be of type cupy.ndarray') |
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if not isinstance(mask, cupy.ndarray): |
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raise TypeError('`mask` should be of type cupy.ndarray') |
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if not (cupy.isscalar(values) or isinstance(values, cupy.ndarray)): |
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raise TypeError('`values` should be of type cupy.ndarray') |
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if not a.shape == mask.shape: |
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raise ValueError('mask and data must be the same size') |
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mask = mask.astype(numpy.bool_) |
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if cupy.isscalar(values): |
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a[mask] = values |
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elif not numpy.can_cast(values.dtype, a.dtype): |
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raise TypeError('Cannot cast array data from' |
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' {} to {} according to the rule \'safe\'' |
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.format(values.dtype, a.dtype)) |
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elif a.shape == values.shape: |
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a[mask] = values[mask] |
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else: |
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values = values.ravel() |
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_putmask_kernel(mask, values, len(values), a) |
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def fill_diagonal(a, val, wrap=False): |
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"""Fills the main diagonal of the given array of any dimensionality. |
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For an array `a` with ``a.ndim > 2``, the diagonal is the list of |
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locations with indices ``a[i, i, ..., i]`` all identical. This function |
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modifies the input array in-place, it does not return a value. |
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Args: |
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a (cupy.ndarray): The array, at least 2-D. |
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val (scalar): The value to be written on the diagonal. |
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Its type must be compatible with that of the array a. |
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wrap (bool): If specified, the diagonal is "wrapped" after N columns. |
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This affects only tall matrices. |
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Examples |
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-------- |
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>>> a = cupy.zeros((3, 3), int) |
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>>> cupy.fill_diagonal(a, 5) |
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>>> a |
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array([[5, 0, 0], |
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[0, 5, 0], |
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[0, 0, 5]]) |
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.. seealso:: :func:`numpy.fill_diagonal` |
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""" |
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if a.ndim < 2: |
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raise ValueError('array must be at least 2-d') |
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end = None |
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if a.ndim == 2: |
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step = a.shape[1] + 1 |
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if not wrap: |
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end = a.shape[1] * a.shape[1] |
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else: |
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if not numpy.all(numpy.diff(a.shape) == 0): |
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raise ValueError('All dimensions of input must be of equal length') |
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step = 1 + numpy.cumprod(a.shape[:-1]).sum() |
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a.flat[:end:step] = val |
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def diag_indices(n, ndim=2): |
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"""Return the indices to access the main diagonal of an array. |
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Returns a tuple of indices that can be used to access the main |
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diagonal of an array with ``ndim >= 2`` dimensions and shape |
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(n, n, ..., n). |
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Args: |
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n (int): The size, along each dimension of the arrays for which |
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the indices are to be returned. |
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ndim (int): The number of dimensions. default `2`. |
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Examples |
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-------- |
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Create a set of indices to access the diagonal of a (4, 4) array: |
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>>> di = cupy.diag_indices(4) |
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>>> di |
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(array([0, 1, 2, 3]), array([0, 1, 2, 3])) |
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>>> a = cupy.arange(16).reshape(4, 4) |
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>>> a |
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array([[ 0, 1, 2, 3], |
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[ 4, 5, 6, 7], |
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[ 8, 9, 10, 11], |
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[12, 13, 14, 15]]) |
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>>> a[di] = 100 |
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>>> a |
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array([[100, 1, 2, 3], |
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[ 4, 100, 6, 7], |
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[ 8, 9, 100, 11], |
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[ 12, 13, 14, 100]]) |
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Create indices to manipulate a 3-D array: |
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>>> d3 = cupy.diag_indices(2, 3) |
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>>> d3 |
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(array([0, 1]), array([0, 1]), array([0, 1])) |
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And use it to set the diagonal of an array of zeros to 1: |
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>>> a = cupy.zeros((2, 2, 2), dtype=int) |
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>>> a[d3] = 1 |
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>>> a |
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array([[[1, 0], |
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[0, 0]], |
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<BLANKLINE> |
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[[0, 0], |
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[0, 1]]]) |
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.. seealso:: :func:`numpy.diag_indices` |
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""" |
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idx = cupy.arange(n) |
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return (idx,) * ndim |
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def diag_indices_from(arr): |
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""" |
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Return the indices to access the main diagonal of an n-dimensional array. |
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See `diag_indices` for full details. |
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Args: |
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arr (cupy.ndarray): At least 2-D. |
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.. seealso:: :func:`numpy.diag_indices_from` |
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""" |
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if not isinstance(arr, cupy.ndarray): |
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raise TypeError("Argument must be cupy.ndarray") |
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if not arr.ndim >= 2: |
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raise ValueError("input array must be at least 2-d") |
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if not cupy.all(cupy.diff(arr.shape) == 0): |
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raise ValueError("All dimensions of input must be of equal length") |
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return diag_indices(arr.shape[0], arr.ndim) |
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