How to replace an re match with a transformation of that match?

Question

For example, I have a string:

The struct-of-application and struct-of-world

With re.sub, it will replace the matched with a predefined string. How can I replace the match with a transformation of the matched content? To get, for example:

The [application_of_struct](http://application_of_struct) and [world-of-struct](http://world-of-struct)

If I write a simple regex ((\w+-)+\w+) and try to use re.sub, it seems I can't use what I matched as part of the replacement, let alone edit the matched content:

In [10]: p.sub('struct','The struct-of-application and struct-of-world')
Out[10]: 'The struct and struct'

Answer 1

Use a function for the replacement

s = 'The struct-of-application and struct-of-world'
p = re.compile('((\w+-)+\w+)')
def replace(match):
    return 'http://{}'.format(match.group())
    #for python 3.6+ ... 
    #return f'http://{match.group()}'

>>> p.sub(replace, s)

'The http://struct-of-application and http://struct-of-world'
>>>

Answer 2

Try this:

>>> p = re.compile(r"((\w+-)+\w+)")
>>> p.sub('[\\1](http://\\1)','The struct-of-application and struct-of-world')
'The [struct-of-application](http://struct-of-application) and [struct-of-world](http://struct-of-world)'