re.sub() problem (regular expression)

[Davy]

Hi all,

I have read a re.sub() that confused me.

s = 'P & Q'
s = re.sub(r'([a-zA-Z0-9_.]+)', r'Expr("\1")', s)

What's "\1" and the whole re.sub() mean?

Best regards,
Davy

 

[Rick Dooling]

What's "\1" and the whole re.sub() mean?

Read about backreferences here:

http://www.regular-expressions.info/brackets.html

Also see the entry on parentheses here:

http://docs.python.org/lib/re-syntax.html

rick