使用布尔索引数组的过滤器列表 [英] Filter list using Boolean index arrays

问题描述

如何在不使用numpy的情况下使用布尔inddex数组过滤列表?

How can I use boolean inddex arrays to filter a list without using numpy?

例如:

>>> l = ['a','b','c']
>>> b = [True,False,False]
>>> l[b]

结果应为:

['a']

我知道numpy支持它，但想知道如何用Python解决.

I know numpy support it but want to know how to solve in Python.

>>> import numpy as np
>>> l = np.array(['a','b','c'])
>>> b = np.array([True,False,False])
>>> l[b]
array(['a'], 
      dtype='|S1')

推荐答案

Python不支持布尔索引，但

Python does not support boolean indexing but the itertools.compress function does exactly what you want. It return an iterator with means you need to use the list constructor to return a list.

>>> from itertools import compress
>>> l = ['a', 'b', 'c']
>>> b = [True, False, False]
>>> list(compress(l, b))
['a']

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