Regex to select the 2nd whitespace after a matched character-CodePudding

I am trying to match the middle whitespace out of 3 whitespaces in a row.

I want to only match the middle whitespace but only if it precedes a |. The actual text I have to match from is this:

 --- --- ---
|   |   |   |
 --- --- ---

I can match 2 whitespaces in a row that precede | with (?<!\|)\s{2} (the xs represent the matches) but I only want to match the x in the middle

 --- --- ---
| xx| xx| xx|
 --- --- ---

CodePudding user response：

What if you try to split the string and use white space as separator, get the substring in the middle then match it to the regex pattern?

CodePudding user response：

You can use grouping to get these specific spaces:
The bolded section relates to the spaces that you want:

(|\s{3}|\s)(\s{2})(|\s{3}|)

Code:

import re

text = """
 --- --- ---
|   |   |   |
 --- --- ---
 """
 
pattern = re.compile(r"(\|\s{3}\|\s)(\s{2})(\|\s{3}\|)")

match = pattern.search(text)
print(match.group(2))

Here is a regex101 : demo

group(0) matches the entire pattern from start to end. | | | |
group(1) matches the pattern before the whitespace of interest
group(2) matches the whitespace of interest
group(3) matches the pattern after the whitespace of interest