numpy.rollaxis

此功能向后滚动指定的轴，直到它位于指定位置。该函数有三个参数。

numpy.rollaxis(arr, axis, start)

这里

序号	参数和描述
1	arr 输入数组
2	axis 轴向后滚动。其他轴的位置不会相对于彼此改变
3	begin 默认为零，导致完整滚动。滚动直到达到指定位置

例

# It creates 3 dimensional ndarray
import numpy as np
a = np.arange(8).reshape(2,2,2)

print 'The original array:'
print a
print '\n'
# to roll axis-2 to axis-0 (along width to along depth)

print 'After applying rollaxis function:'
print np.rollaxis(a,2)  
# to roll axis 0 to 1 (along width to height)
print '\n'

print 'After applying rollaxis function:'
print np.rollaxis(a,2,1)

其输出如下

The original array:
[[[0 1]
 [2 3]]
 [[4 5]
 [6 7]]]

After applying rollaxis function:
[[[0 2]
 [4 6]]
 [[1 3]
 [5 7]]]

After applying rollaxis function:
[[[0 2]
 [1 3]]
 [[4 6]
 [5 7]]]