Conditional Regex Substition in Python

Question

I have a regex like this

value = ">>897897"
rep = "<div> \\1 </div>"
pat = "&gt;&gt;(\\d+)"
res = re.sub(pat, rep, value)

But now I want to add a condition that when the number equals a certain number, like 50, it uses a different substition.

For example if match equals 50:

use

rep = "<p> \\1 </p>"

instead of

rep = "<div> \\1 </div>"

First get the matched digits then based in its value call next regex to replaced it with desired one. — Braj
– Braj, Commented Jun 24, 2014 at 18:20

Aamir Rind · Accepted Answer · 2014-06-24 18:20:37Z

3

Yes you can use a function as replacement and do the conditional checks there:

def check(match):
    g = match.group(1) # group(1) or any group number you have
    if g == '50':
        return '<p>%s</p>' % g
    else:
        return '<div>%s</div>' % g

res = re.sub(pat, check, value)

answered Jun 24, 2014 at 18:20

Aamir Rind

39.8k24 gold badges131 silver badges169 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jonathan Villemaire-Krajden · Accepted Answer · 2014-06-24 18:22:34Z

2

You can use a function instead of a replacement pattern in re.sub. The function will be passed the match object. So for example:

re.sub(r'(\d+)', lambda m: "-" + m.group(0) + "-" if m.group(0) != "50" else "*"+m.group(0)+"*", "a 50 b")
# gives 'a *50* b'
re.sub(r'(\d+)', lambda m: "-" + m.group(0) + "-" if m.group(0) != "50" else "*"+m.group(0)+"*", "a 64 b")
# gives 'a -64- b'

answered Jun 24, 2014 at 18:22

Jonathan Villemaire-Krajden

1,47811 silver badges22 bronze badges

Collectives™ on Stack Overflow

Conditional Regex Substition in Python

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related