NumPy numpy.broadcast 函数

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  简述

  如前所述，NumPy 具有对广播的内置支持。此功能模仿广播机制。它返回一个对象，该对象封装了将一个数组广播到另一个数组的结果。

  该函数将两个数组作为输入参数。下面的例子说明了它的使用。
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  例子

  
  import numpy as np 
  x = np.array([[1], [2], [3]]) 
  y = np.array([4, 5, 6])  
     
  # tobroadcast x against y 
  b = np.broadcast(x,y)  
  # it has an iterator property, a tuple of iterators along self's "components." 
  print 'Broadcast x against y:' 
  r,c = b.iters 
  print r.next(), c.next() 
  print r.next(), c.next() 
  print '\n'  
  # shape attribute returns the shape of broadcast object 
  print 'The shape of the broadcast object:' 
  print b.shape 
  print '\n'  
  # to add x and y manually using broadcast 
  b = np.broadcast(x,y) 
  c = np.empty(b.shape) 
  print 'Add x and y manually using broadcast:' 
  print c.shape 
  print '\n'  
  c.flat = [u + v for (u,v) in b] 
  print 'After applying the flat function:' 
  print c 
  print '\n'  
  # same result obtained by NumPy's built-in broadcasting support 
  print 'The summation of x and y:' 
  print x + y
  

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  它的输出如下 -

  
  Broadcast x against y:
  1 4
  1 5
  The shape of the broadcast object:
  (3, 3)
  Add x and y manually using broadcast:
  (3, 3)
  After applying the flat function:
  [[ 5. 6. 7.]
   [ 6. 7. 8.]
   [ 7. 8. 9.]]
  The summation of x and y:
  [[5 6 7]
   [6 7 8]
   [7 8 9]]
  

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