NumPy numpy.rollaxis 函数

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  简述

  此函数向后滚动指定轴，直到它位于指定位置。该函数接受三个参数。

  
  numpy.rollaxis(arr, axis, start)
  

  参数说明

  序号	参数及说明
  1	arr 输入数组
  2	axis 轴向后滚动。其他轴的位置相对于彼此不会改变
  3	start 默认为零导致完整的滚动。滚动直到到达指定位置

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  例子

  
  # 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)
  

  它的输出如下 -

  
  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]]]