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comp.lang.python

Re: small problem with re.sub

Gabriel Genellina

1/31/2008 3:50:00 AM

En Thu, 31 Jan 2008 01:01:30 -0200, Astan Chee <stanc@al.com.au> escribió:

> I have a html text stored as a string. Now I want to go through this
> string and find all 6 digit numbers and make links from them.
> Im using re.sub and for some reason its not picking up the previously
> matched condition. Am I doing something wrong? This is what my code
> looks like:
> htmlStr = re.sub('(?P<id>\d{6})','<a
> href=\"http://...(?P=id).html\">(?P=id)</a>',htmlStr)
> It seems that it replaces it alright, but it replaces it literally. Am I
> not escaping certain characters?

Two errors:
- use raw strings r"..." to write regular expressions (or quote every
backslash...)
- if you want to *substitute* a named group, the syntax is "\g<name>"; you
have used the syntax to *match* a named group.

re.sub(r'(?P<id>\d{6})',r'<a
href="http://...\g<id>.html">\g<id></a>',htmlStr)

In simple cases like this, may be easier to just use a number:

re.sub(r'(\d{6})',r'<a href="http://...\1.html">\1</a>',htmlStr)

--
Gabriel Genellina