Re: re.sub(): replace longest match instead of leftmost match?

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Date	Fri, 16 Dec 2011 21:36:34 +0000
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Subject	Re: re.sub(): replace longest match instead of leftmost match?
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On 16/12/2011 21:04, John Gordon wrote:
> In<mailman.3737.1324054637.27778.python-list@python.org>  Devin Jeanpierre<jeanpierreda@gmail.com>  writes:
>
>>  You could use re.finditer to find the longest match, and then replace
>>  it manually by hand (via string slicing).
>
>>  (a match is the longest if (m.end() - m.start()) is the largest --
>>  so, max(re.finditer(...), key=3Dlambda m: (m.end() =3D m.start()))
>
> I ended up doing something similar:
>
>      # find the longest match
>      longest_match = ''
>      for word in re.findall('((0000:?)+)', ip6):
>          if len(word[0])>  len(longest_match):
>              longest_match = word[0]
>
>      # if we found a match, replace it with a colon
>      if longest_match:
>        ip6 = re.sub(longest_match, ':', ip6, 1)
>
For a simple replace, using re is probably overkill. The .replace
method is a better solution:

ip6 = longest_match.replace(ip6, ':', 1)

Thread

re.sub(): replace longest match instead of leftmost match? John Gordon <gordon@panix.com> - 2011-12-16 16:49 +0000
  Re: re.sub(): replace longest match instead of leftmost match? Devin Jeanpierre <jeanpierreda@gmail.com> - 2011-12-16 11:56 -0500
    Re: re.sub(): replace longest match instead of leftmost match? John Gordon <gordon@panix.com> - 2011-12-16 21:04 +0000
      Re: re.sub(): replace longest match instead of leftmost match? MRAB <python@mrabarnett.plus.com> - 2011-12-16 21:36 +0000
        Re: re.sub(): replace longest match instead of leftmost match? Duncan Booth <duncan.booth@invalid.invalid> - 2011-12-19 15:46 +0000
  Re: re.sub(): replace longest match instead of leftmost match? MRAB <python@mrabarnett.plus.com> - 2011-12-16 17:36 +0000
  Re: re.sub(): replace longest match instead of leftmost match? Ian Kelly <ian.g.kelly@gmail.com> - 2011-12-16 10:57 -0700
  Re: re.sub(): replace longest match instead of leftmost match? Ian Kelly <ian.g.kelly@gmail.com> - 2011-12-16 10:59 -0700
    Re: re.sub(): replace longest match instead of leftmost match? John Gordon <gordon@panix.com> - 2011-12-16 21:06 +0000
  Re: re.sub(): replace longest match instead of leftmost match? MRAB <python@mrabarnett.plus.com> - 2011-12-16 18:19 +0000
  Re: re.sub(): replace longest match instead of leftmost match? Roy Smith <roy@panix.com> - 2011-12-16 13:36 -0500
    Re: re.sub(): replace longest match instead of leftmost match? John Gordon <gordon@panix.com> - 2011-12-16 21:07 +0000
    Re: re.sub(): replace longest match instead of leftmost match? Terry Reedy <tjreedy@udel.edu> - 2011-12-16 17:26 -0500
  Re: re.sub(): replace longest match instead of leftmost match? ting@thsu.org - 2011-12-19 15:15 -0800
    Re: re.sub(): replace longest match instead of leftmost match? Ian Kelly <ian.g.kelly@gmail.com> - 2011-12-19 19:58 -0700

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