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1"""
2Miscellaneous utils.
3"""
4from numpy._core import asarray
5from numpy._core.numeric import normalize_axis_tuple, normalize_axis_index
6from numpy._utils import set_module
8__all__ = ["byte_bounds", "normalize_axis_tuple", "normalize_axis_index"]
11@set_module("numpy.lib.array_utils")
12def byte_bounds(a):
13 """
14 Returns pointers to the end-points of an array.
16 Parameters
17 ----------
18 a : ndarray
19 Input array. It must conform to the Python-side of the array
20 interface.
22 Returns
23 -------
24 (low, high) : tuple of 2 integers
25 The first integer is the first byte of the array, the second
26 integer is just past the last byte of the array. If `a` is not
27 contiguous it will not use every byte between the (`low`, `high`)
28 values.
30 Examples
31 --------
32 >>> import numpy as np
33 >>> I = np.eye(2, dtype='f'); I.dtype
34 dtype('float32')
35 >>> low, high = np.lib.array_utils.byte_bounds(I)
36 >>> high - low == I.size*I.itemsize
37 True
38 >>> I = np.eye(2); I.dtype
39 dtype('float64')
40 >>> low, high = np.lib.array_utils.byte_bounds(I)
41 >>> high - low == I.size*I.itemsize
42 True
44 """
45 ai = a.__array_interface__
46 a_data = ai['data'][0]
47 astrides = ai['strides']
48 ashape = ai['shape']
49 bytes_a = asarray(a).dtype.itemsize
51 a_low = a_high = a_data
52 if astrides is None:
53 # contiguous case
54 a_high += a.size * bytes_a
55 else:
56 for shape, stride in zip(ashape, astrides):
57 if stride < 0:
58 a_low += (shape-1)*stride
59 else:
60 a_high += (shape-1)*stride
61 a_high += bytes_a
62 return a_low, a_high