如何从多维数组中提取一列? [英] How do you extract a column from a multi-dimensional array?

问题描述

有人知道如何在 Python 中从多维数组中提取一列吗?

Does anybody know how to extract a column from a multi-dimensional array in Python?

推荐答案

>>> import numpy as np
>>> A = np.array([[1,2,3,4],[5,6,7,8]])

>>> A
array([[1, 2, 3, 4],
    [5, 6, 7, 8]])

>>> A[:,2] # returns the third columm
array([3, 7])

另见:numpy.arange"和reshape"来分配内存

See also: "numpy.arange" and "reshape" to allocate memory

示例:(分配具有矩阵 (3x4) 整形的数组)

Example: (Allocating a array with shaping of matrix (3x4))

nrows = 3
ncols = 4
my_array = numpy.arange(nrows*ncols, dtype='double')
my_array = my_array.reshape(nrows, ncols)

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