python:仅在此列表内时保留char [英] python: keep char only if it is within this list

问题描述

我有一个列表:

a = ['a','b','c'.........'A','B','C'.........'Z']

我有一个字符串:

string1= 's#$%ERGdfhliisgdfjkskjdfW$JWLI3590823r'

我只想保留a

最有效的方法是什么?也许不是让a成为列表，我应该将其设为字符串?像这样a='abcdefg..........ABC..Z' ??

what is the most effecient way to do this? perhaps instead of having a be a list, i should just make it a string? like this a='abcdefg..........ABC..Z' ??

推荐答案

''.join([s for s in string1 if s in a])

说明:

[s for s in string1 if s in a]

创建一个字符串1中所有字符的列表，但前提是它们也位于列表a中.

creates a list of all characters in string1, but only if they are also in the list a.

''.join([...])

通过在给定列表的元素之间不添加任何字符('')将其转换为字符串.

turns it back into a string by joining it with nothing ('') in between the elements of the given list.

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