New to regex - retrieve a question mark

Question

I am quite new to regex and I would like to know if there was a way to match something that is either a normal character : \w+ or a question mark. I am trying to retrieve the value after the n.

The line has this format :

n : ?, t : 0.4

The thing that follows n can also be an integer :

n : 3, t : 0.7

So far I have :

import re
line = "n : 4, t : 0.4"
value = re.findall(r'\w : (\w+), \w : \d\.\d+', line)

How can I change this to take into account the fact that line can contain a question mark ?

Expected output :

if following n is a ?, value should be None
if following n is an integer, value should be that integer

The question mark is really a question mark in my ```.txt``` file. If it's not then it's an integer — Maxime Bouhadana, Jul 08 '22 at 07:57
try regex101.com, this website gives some more context and room to play with things. Note that you need to set it python first. — Pieter Geelen, Jul 08 '22 at 07:57

score 1 · Accepted Answer · answered Jul 08 '22 at 07:56

You want to use the "Alternate" regex symbol.

Your regex should therefore be: \w : (\w+|\?), \w : \d\.\d+. Do not forget to escape the question mark, since it is also a regex symbol.

EDIT: If the value following n must be either an integer or a ?, you can use \d to match a digit, and \d+ to match a number (with multiple digits). Your regex would become \w : (\d+|\?), \w : \d\.\d+

New to regex - retrieve a question mark

1 Answers1