Numpy Array忽略对角线的最小值 [英] Minimum of Numpy Array Ignoring Diagonal
问题描述
我必须忽略对角线元素而找到一个numpy数组的最大值.
I have to find the maximum value of a numpy array ignoring the diagonal elements.
np.amax()提供了忽略特定轴来查找它的方法.忽略所有对角线元素,如何实现相同的效果?
np.amax() provides ways to find it ignoring specific axes. How can I achieve the same ignoring all the diagonal elements?
推荐答案
您可以使用面具
mask = np.ones(a.shape, dtype=bool)
np.fill_diagonal(mask, 0)
max_value = a[mask].max()
其中,a
是要查找最大值的矩阵.遮罩会选择非对角线元素,因此a[mask]
将是所有非对角线元素的长向量.然后,您就拿最大的.
where a
is the matrix you want to find the max of. The mask selects the off-diagonal elements, so a[mask]
will be a long vector of all the off-diagonal elements. Then you just take the max.
或者,如果您不介意修改原始数组
Or, if you don't mind modifying the original array
np.fill_diagonal(a, -np.inf)
max_value = a.max()
当然,您始终可以进行复制,然后执行上述操作而无需修改原始文档.另外,这是假设a
是某种浮点格式.
Of course, you can always make a copy and then do the above without modifying the original. Also, this is assuming that a
is some floating point format.
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