字符串上的Numpy'where' [英] Numpy 'where' on string

问题描述

我想在字符串数组上使用numpy.where函数.但是，我这样做没有成功.有人可以帮我解决这个问题吗?

I would like to use the numpy.where function on a string array. However, I am unsuccessful in doing so. Can someone please help me figure this out?

例如，当我在以下示例中使用numpy.where时，出现错误:

For example, when I use numpy.where on the following example I get an error:

import numpy as np

A = ['apple', 'orange', 'apple', 'banana']

arr_index = np.where(A == 'apple',1,0)

我得到以下信息:

>>> arr_index
array(0)
>>> print A[arr_index]
>>> apple

但是，我想知道字符串'apple'匹配的字符串数组A中的索引.在上面的字符串中，这发生在0和2.但是，np.where仅返回0，而不返回2.

However, I would like to know the indices in the string array, A where the string 'apple' matches. In the above string this happens at 0 and 2. However, the np.where only returns 0 and not 2.

那么，如何使numpy.where在字符串上工作?提前致谢.

So, how do I make numpy.where work on strings? Thanks in advance.

推荐答案

print a[arr_index]

不是array_index !!

a = np.array(['apple', 'orange', 'apple', 'banana'])

arr_index = np.where(a == 'apple')

print arr_index

print a[arr_index]

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