检查不同 numpy 数组中的相同行 [英] check for identical rows in different numpy arrays

问题描述

如何在逐行真/假数组的结果中获得两个数组之间的逐行比较?

how do I get a row-wise comparison between two arrays, in the result of a row-wise true/false array?

给定数据:

a = np.array([[1,0],[2,0],[3,1],[4,2]])
b = np.array([[1,0],[2,0],[4,2]])

结果步骤 1:

c = np.array([True, True,False,True])

最终结果:

a = a[c]

那么我如何获得数组 c ????

So how do I get the array c ????

P.S.:在本例中，数组 a 和 b 已排序，如果在您的解决方案中数组排序很重要，请提供信息

P.S.: In this example the arrays a and b are sorted, please give also information if in your solution it is important that the arrays are sorted

推荐答案

这是一个矢量化的解决方案:

Here's a vectorised solution:

res = (a[:, None] == b).all(-1).any(-1)

print(res)

array([ True,  True, False,  True])

注意 a[:, None] == b 将 a 的每一行与 b 元素进行比较.然后我们使用 all + any 来推断每个子数组是否有任何行都是 True :

Note that a[:, None] == b compares each row of a with b element-wise. We then use all + any to deduce if there are any rows which are all True for each sub-array:

print(a[:, None] == b)

[[[ True  True]
  [False  True]
  [False False]]

 [[False  True]
  [ True  True]
  [False False]]

 [[False False]
  [False False]
  [False False]]

 [[False False]
  [False False]
  [ True  True]]]

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