改变nparray的形状 [英] Change shape of nparray

问题描述

import numpy as np
​
image1 = np.zeros((120, 120))
image2 = np.zeros((120, 120))
image3 = np.zeros((120, 120))
​
pack1 = np.array([image1,image2,image3])
pack2 = np.array([image1,image2,image3])
​
result = np.array([pack1,pack2])

print result.shape

结果是: (2，3，120，120)

the result is : (2, 3, 120, 120)

问题:如何在不混合的情况下用相同的数据制作形状为(2,120,120,3)的数组?

Question : how can I make array with shape (2,120,120,3) with same data without mixing?

推荐答案

使用np.rollaxis将单轴移动(确定，滚动)到指定位置:

Use np.rollaxis to move (OK, roll) a single axis to a specified position:

>>> a.shape
(2, 3, 11, 11)
>>> np.rollaxis(a, 0, 4).shape
(3, 11, 11, 2)

这里的语法是滚动第0根轴，使其成为新数组中的第4根".

Here the syntax is "roll the zeroth axis so that it becomes the 4th in the new array".

请注意，rollaxis创建了一个视图且未复制:

Notice that rollaxis creates a view and does not copy:

>>> np.rollaxis(a, 0, 4).base is a
True

另一种方法(通常是更易读的方法)是使用np.transpose接受将轴放置在何处的元组这一事实.观察:

An alternative (and often more readable) way would be to use the fact that np.transpose accepts a tuple of where to place the axes. Observe:

>>> np.transpose(a, (1, 2, 3, 0)).shape
(3, 11, 11, 2)
>>> np.transpose(a, (1, 2, 3, 0)).base is a
True

这里的语法是对轴进行置换，以使原始数组中的第零个轴成为新数组中的第四个轴"

Here the syntax is "permute the axes so that what was the zeroth axis in the original array becomes the 4th axis in the new array"

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