Python replace string pattern with output of function

Question

I have a string in Python, say The quick @red fox jumps over the @lame brown dog.

I\'m trying to replace each of the words that begin with @

Answer 1

I wasn't aware you could pass a function to a re.sub() either. Riffing on @Janne Karila's answer to solve a problem I had, the approach works for multiple capture groups, too.

import re

def my_replace(match):
    match1 = match.group(1)
    match2 = match.group(2)
    match2 = match2.replace('@', '')
    return u"{0:0.{1}f}".format(float(match1), int(match2))

string = 'The first number is 14.2@1, and the second number is 50.6@4.'
result = re.sub(r'([0-9]+.[0-9]+)(@[0-9]+)', my_replace, string)

print(result)

Output:

The first number is 14.2, and the second number is 50.6000.

This simple example requires all capture groups be present (no optional groups).