如何使用Python正则表达式重复n次带括号的组？

Question

I'm trying to get pairs of |<digit><whitespace> out of a string with many of them. I'm using the regex (\\|\\d+\\s+){2} to do this, ie:

>>> import re
>>> s = '|11 |22    |\n|33  |444 |\n'
>>> re.findall('(\|\d+\s+){2}', s)
['|22    ', '|444 ']

I expected instead is:

['|11 |22    |', '|33  |444 |']

because () should define a group and {2} should repeat it twice. Why doesn't it do that, and what's a better way of doing it?

Answer 1

Turn the capturing group to non-capturing group and add a \\| at the last in your regex. Because re.findall will return the captured characters if there any capturing group else it would return all the matched characters. since your regex contain one greedy capturing group, it captures only the last repeat but matches all the previous repeats.

>>> s = '|11 |22    |\n|33  |444 |\n'
>>> re.findall('(?:\|\d+\s+){2}\|', s)
['|11 |22    |', '|33  |444 |']