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#就是轴的互换，如下例，b是2*4的ndarray，把0轴（2）和一轴（4）换了，就成了4*2的ndarray
b = array([[0, 1, 2, 3],
[4, 5, 6, 7]])
np.swapaxes(b,0,1)
b
>>>array([[0, 4],
[1, 5],
[2, 6],
[3, 7]])From: https://zhidao.baidu.com/question/308918610789546324.html
Numpy实现增加数组维度
方法一：用None作为索引
a = np.array([1,2,3]) # a.shape = (3,)
a = a[None,:] # a.shape =（1，3）方法二：用np.newaxis
a = np.array([1,2,3]) # a.shape = (3,)
a = a[np.newaxis,:] # a.shape =（1，3）From：【Python】Numpy实现增加数组维度
eg
import numpy as np
a = np.array([1,2,3,4,5]) # a.shape = (3,)
print(a)
a = a[np.newaxis,:] # a.shape =（1，3）
print(a)
a = a[np.newaxis,:] # a.shape =（1，3）
print(a)[1 2 3 4 5]
[[1 2 3 4 5]]
[[[1 2 3 4 5]]]