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Groups > comp.lang.python > #36154

Re: Need a specific sort of string modification. Can someone help?

From Frank Millman <frank@chagford.com>
Subject Re: Need a specific sort of string modification. Can someone help?
Date 2013-01-05 11:15 +0200
References <e480480d-f3b4-4491-969c-7d1843bf9e33@googlegroups.com>
Newsgroups comp.lang.python
Message-ID <mailman.108.1357377381.2939.python-list@python.org> (permalink)

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On 05/01/2013 10:35, Sia wrote:
> I have strings such as:
>
> tA.-2AG.-2AG,-2ag
> or
> .+3ACG.+5CAACG.+3ACG.+3ACG
>
> The plus and minus signs are always followed by a number (say, i). I want python to find each single plus or minus, remove the sign, the number after it and remove i characters after that. So the two strings above become:
>
> tA..,
> and
> ...
>
> How can I do that?
> Thanks.
>

Here is a naive solution (I am sure there are more elegant ones) -

def strip(old_string):
     new_string = ''
     max = len(old_string)
     pos = 0
     while pos < max:
         char = old_string[pos]
         if char in ('-', '+'):
             num_pos = pos+1
             num_str = ''
             while old_string[num_pos].isdigit():
                 num_str += old_string[num_pos]
                 num_pos += 1
             pos = num_pos + int(num_str)
         else:
             new_string += old_string[pos]
             pos += 1
     return new_string

It caters for the possibility that the number following the +/- could be 
greater than 9 - I don't know if you need that.

It works with your examples, except that the second one returns '....', 
which I think is correct - there are 4 dots in the original string.

HTH

Frank Millman

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Thread

Need a specific sort of string modification. Can someone help? Sia <hossein.asgharian@gmail.com> - 2013-01-05 00:35 -0800
  Re: Need a specific sort of string modification. Can someone help? Frank Millman <frank@chagford.com> - 2013-01-05 11:15 +0200
  Re: Need a specific sort of string modification. Can someone help? Chris Angelico <rosuav@gmail.com> - 2013-01-05 20:27 +1100
    Re: Need a specific sort of string modification. Can someone help? Roy Smith <roy@panix.com> - 2013-01-05 09:30 -0500
      Re: Need a specific sort of string modification. Can someone help? Chris Angelico <rosuav@gmail.com> - 2013-01-06 01:47 +1100
        Re: Need a specific sort of string modification. Can someone help? Roy Smith <roy@panix.com> - 2013-01-05 10:03 -0500
          Re: Need a specific sort of string modification. Can someone help? Chris Angelico <rosuav@gmail.com> - 2013-01-06 02:09 +1100
            Re: Need a specific sort of string modification. Can someone help? Roy Smith <roy@panix.com> - 2013-01-05 10:38 -0500
              Re: Need a specific sort of string modification. Can someone help? Chris Angelico <rosuav@gmail.com> - 2013-01-06 02:57 +1100
              Re: Need a specific sort of string modification. Can someone help? Ian Kelly <ian.g.kelly@gmail.com> - 2013-01-05 13:04 -0700
              Re: Need a specific sort of string modification. Can someone help? Chris Angelico <rosuav@gmail.com> - 2013-01-06 07:32 +1100
                Re: Need a specific sort of string modification. Can someone help? Roy Smith <roy@panix.com> - 2013-01-05 15:47 -0500
                Re: Need a specific sort of string modification. Can someone help? Roy Smith <roy@panix.com> - 2013-01-06 12:28 -0500
                Re: Need a specific sort of string modification. Can someone help? Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2013-01-06 23:19 +0000
  Re: Need a specific sort of string modification. Can someone help? Roy Smith <roy@panix.com> - 2013-01-05 09:12 -0500
  Re: Need a specific sort of string modification. Can someone help? Tim Chase <python.list@tim.thechases.com> - 2013-01-05 11:24 -0600
  Re: Need a specific sort of string modification. Can someone help? Tim Chase <python.list@tim.thechases.com> - 2013-01-05 12:49 -0600
  Re: Need a specific sort of string modification. Can someone help? Mitya Sirenef <msirenef@lightbird.net> - 2013-01-06 01:32 -0500
  Re: Need a specific sort of string modification. Can someone help? Mitya Sirenef <msirenef@lightbird.net> - 2013-01-06 14:53 -0500
  Re: Need a specific sort of string modification. Can someone help? Nick Mellor <thebalancepro@gmail.com> - 2013-01-06 18:48 -0800
  Re: Need a specific sort of string modification. Can someone help? Nick Mellor <thebalancepro@gmail.com> - 2013-01-06 19:40 -0800
    Re: Need a specific sort of string modification. Can someone help? Nick Mellor <thebalancepro@gmail.com> - 2013-01-06 21:28 -0800
  Re: Need a specific sort of string modification. Can someone help? Nick Mellor <thebalancepro@gmail.com> - 2013-01-06 21:30 -0800
  Re: Need a specific sort of string modification. Can someone help? John Ladasky <john_ladasky@sbcglobal.net> - 2013-01-06 21:39 -0800
  Re: Need a specific sort of string modification. Can someone help? Nick Mellor <thebalancepro@gmail.com> - 2013-01-06 23:07 -0800

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