NumPy numpy.expand_dims 函数

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  简述

  此函数通过在指定位置插入新轴来扩展数组。此函数需要两个参数。

  
  numpy.expand_dims(arr, axis)
  

  参数说明

  序号	参数及说明
  1	arr 输入数组
  2	axis 要插入新轴的位置

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  例子

  
  import numpy as np 
  x = np.array(([1,2],[3,4])) 
  print 'Array x:' 
  print x 
  print '\n'  
  y = np.expand_dims(x, axis = 0) 
  print 'Array y:' 
  print y 
  print '\n'
  print 'The shape of X and Y array:' 
  print x.shape, y.shape 
  print '\n'  
  # insert axis at position 1 
  y = np.expand_dims(x, axis = 1) 
  print 'Array Y after inserting axis at position 1:' 
  print y 
  print '\n'  
  print 'x.ndim and y.ndim:' 
  print x.ndim,y.ndim 
  print '\n'  
  print 'x.shape and y.shape:' 
  print x.shape, y.shape
  

  上述程序的输出如下 -

  
  Array x:
  [[1 2]
   [3 4]]
  Array y:
  [[[1 2]
   [3 4]]]
  The shape of X and Y array:
  (2, 2) (1, 2, 2)
  Array Y after inserting axis at position 1:
  [[[1 2]]
   [[3 4]]]
  x.ndim and y.ndim:
  2 3
  x.shape and y.shape:
  (2, 2) (2, 1, 2)