"""
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Miscellaneous utils.
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"""
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from numpy._core import asarray
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from numpy._core.numeric import normalize_axis_index, normalize_axis_tuple
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from numpy._utils import set_module
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__all__ = ["byte_bounds", "normalize_axis_tuple", "normalize_axis_index"]
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@set_module("numpy.lib.array_utils")
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def byte_bounds(a):
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"""
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Returns pointers to the end-points of an array.
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Parameters
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----------
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a : ndarray
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Input array. It must conform to the Python-side of the array
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interface.
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Returns
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-------
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(low, high) : tuple of 2 integers
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The first integer is the first byte of the array, the second
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integer is just past the last byte of the array. If `a` is not
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contiguous it will not use every byte between the (`low`, `high`)
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values.
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Examples
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--------
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>>> import numpy as np
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>>> I = np.eye(2, dtype='f'); I.dtype
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dtype('float32')
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>>> low, high = np.lib.array_utils.byte_bounds(I)
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>>> high - low == I.size*I.itemsize
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True
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>>> I = np.eye(2); I.dtype
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dtype('float64')
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>>> low, high = np.lib.array_utils.byte_bounds(I)
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>>> high - low == I.size*I.itemsize
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True
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"""
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ai = a.__array_interface__
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a_data = ai['data'][0]
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astrides = ai['strides']
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ashape = ai['shape']
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bytes_a = asarray(a).dtype.itemsize
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a_low = a_high = a_data
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if astrides is None:
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# contiguous case
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a_high += a.size * bytes_a
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else:
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for shape, stride in zip(ashape, astrides):
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if stride < 0:
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a_low += (shape - 1) * stride
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else:
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a_high += (shape - 1) * stride
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a_high += bytes_a
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return a_low, a_high
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