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