在文件中查找字符串的最快方法 [英] The fastest way to find a string inside a file

问题描述

我尝试了多种在文件中查找字符串的方法，但都很慢.我只需要:

I have tried many ways of looking for a string inside a file, but all were slow. All I need is:

• 在文件中查找字符串
• 打印字符串所在的行

到现在为止我所做的只是读取文件(尝试了很多方法)然后检查我要查找的字符串是否位于当前行中.如果不是，请检查下一行等

All I've been doing until now was reading a file (tried many ways) and then checking whether the string I am looking for is located in the current line. If not, check the next line, etc.

这样做的最佳方法是什么?

推荐答案

以下将适用于子字符串 something 的第一次出现.None 如果没有找到匹配，则赋值；文件被延迟读取到第一个匹配项.

The following will work for the fist occurrence of a substring something. None is assigned if no match is found; file is read lazily up to the first match.

with open('input.txt') as f:
    line = next((l for l in f if something in l), None)

要查找所有匹配项，您可以使用列表推导式:

To find all matches, you can use a list comprehension:

with open('input.txt') as f:
    lines = [l for l in f if something in l]

我不知道你在纯 python 中是否可以比这快得多.

I do not know if you can be much faster than this in pure python.

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