问题描述
是否有numpy/scipy的matlab中的find(A>9,1)等效功能.我知道numpy中有nonzero函数，但我需要的是第一个索引，以便可以在另一个提取的列中使用第一个索引.
Is there an equivalent function of find(A>9,1) from matlab for numpy/scipy. I know that there is the nonzero function in numpy but what I need is the first index so that I can use the first index in another extracted column.
例如:A = [ 1 2 3 9 6 4 3 10 ]find(A>9,1)将在matlab中返回索引4
Ex: A = [ 1 2 3 9 6 4 3 10 ]find(A>9,1) would return index 4 in matlab
推荐答案
numpy中find的等效项是nonzero，但它不支持第二个参数.但是您可以执行类似的操作来获得您想要的行为.
The equivalent of find in numpy is nonzero, but it does not support a second parameter.But you can do something like this to get the behavior you are looking for.
B = nonzero(A >= 9)[0]
但是，如果您要寻找的是找到满足条件的第一个元素，那么最好使用max.
But if all you are looking for is finding the first element that satisfies a condition, you are better off using max.
例如，在matlab中，find(A >= 9, 1)将与[idx, B] = max(A >= 9)相同. numpy中的等效函数如下.
For example, in matlab, find(A >= 9, 1) would be the same as [idx, B] = max(A >= 9). The equivalent function in numpy would be the following.
idx = (A >= 9).argmax()
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