numpy获取索引，其中值是true [英] numpy get index where value is true

问题描述

>>> ex=np.arange(30)
>>> e=np.reshape(ex,[3,10])
>>> e
array([[ 0,  1,  2,  3,  4,  5,  6,  7,  8,  9],
       [10, 11, 12, 13, 14, 15, 16, 17, 18, 19],
       [20, 21, 22, 23, 24, 25, 26, 27, 28, 29]])
>>> e>15
array([[False, False, False, False, False, False, False, False, False,
        False],
       [False, False, False, False, False, False,  True,  True,  True,
         True],
       [ True,  True,  True,  True,  True,  True,  True,  True,  True,
         True]], dtype=bool)

我需要找到具有true的行或e中值大于15的行.我可以使用for循环进行迭代，但是，我想知道是否有numpy可以执行更多操作有效吗?

I need to find the rows that have true or rows in e whose value are more than 15. I could iterate using a for loop, however, I would like to know if there is a way numpy could do this more efficiently?

推荐答案

要获取至少一项大于15的行号:

To get the row numbers where at least one item is larger than 15:

>>> np.where(np.any(e>15, axis=1))
(array([1, 2], dtype=int64),)

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