Re: how to avoid leading white spaces

From	Chris Torek <nospam@torek.net>
Newsgroups	comp.lang.python
Subject	Re: how to avoid leading white spaces
Date	2011-06-03 21:45 +0000
Organization	None of the Above
Message-ID	<isbkl301v7v@news2.newsguy.com> (permalink)
References	<BANLkTikjY3U9Y24s-GOEyi8CNqCFLXuG6g@mail.gmail.com> <4de8eef1$0$29996$c3e8da3$5496439d@news.astraweb.com> <1237a287-10b0-4a2d-ba35-97b5238deda1@n11g2000yqf.googlegroups.com> <94svm4Fe7eU1@mid.individual.net>

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>On 2011-06-03, rurpy@yahoo.com <rurpy@yahoo.com> wrote:
[prefers]
>>     re.split ('[ ,]', source)

This is probably not what you want in dealing with
human-created text:

    >>> re.split('[ ,]', 'foo bar, spam,maps')
    ['foo', '', 'bar', '', 'spam', 'maps']

Instead, you probably want "a comma followed by zero or
more spaces; or, one or more spaces":

    >>> re.split(r',\s*|\s+', 'foo bar, spam,maps')
    ['foo', 'bar', 'spam', 'maps']

or perhaps (depending on how you want to treat multiple
adjacent commas) even this:

    >>> re.split(r',+\s*|\s+', 'foo bar, spam,maps,, eggs')
    ['foo', 'bar', 'spam', 'maps', 'eggs']

although eventually you might want to just give in and use the
csv module. :-)  (Especially if you want to be able to quote
commas, for instance.)

>> ...  With regexes the code is likely to be less brittle than a
>> dozen or more lines of mixed string functions, indexes, and
>> conditionals.

In article <94svm4Fe7eU1@mid.individual.net>
Neil Cerutti  <neilc@norwich.edu> wrote:
[lots of snippage]
>That is the opposite of my experience, but YMMV.

I suspect it depends on how familiar the user is with regular
expressions, their abilities, and their limitations.

People relatively new to REs always seem to want to use them
to count (to balance parentheses, for instance).  People who
have gone through the compiler course know better. :-)
-- 
In-Real-Life: Chris Torek, Wind River Systems
Salt Lake City, UT, USA (40°39.22'N, 111°50.29'W)  +1 801 277 2603
email: gmail (figure it out)      http://web.torek.net/torek/index.html

Thread

Re: how to avoid leading white spaces Chris Rebert <clp2@rebertia.com> - 2011-06-01 10:11 -0700
  Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-01 12:39 -0700
    Re: how to avoid leading white spaces Karim <karim.liateni@free.fr> - 2011-06-01 22:34 +0200
    Re: how to avoid leading white spaces Neil Cerutti <neilc@norwich.edu> - 2011-06-02 13:21 +0000
      Re: how to avoid leading white spaces Roy Smith <roy@panix.com> - 2011-06-02 21:57 -0400
        Re: how to avoid leading white spaces MRAB <python@mrabarnett.plus.com> - 2011-06-03 03:41 +0100
        Re: how to avoid leading white spaces Chris Torek <nospam@torek.net> - 2011-06-03 02:58 +0000
          Re: how to avoid leading white spaces Roy Smith <roy@panix.com> - 2011-06-02 23:44 -0400
            Re: how to avoid leading white spaces Chris Angelico <rosuav@gmail.com> - 2011-06-03 13:52 +1000
            Re: how to avoid leading white spaces Chris Angelico <rosuav@gmail.com> - 2011-06-03 13:54 +1000
            Re: how to avoid leading white spaces Chris Torek <nospam@torek.net> - 2011-06-03 04:30 +0000
              Re: how to avoid leading white spaces Nobody <nobody@nowhere.com> - 2011-06-03 14:11 +0100
          Re: how to avoid leading white spaces Nobody <nobody@nowhere.com> - 2011-06-03 14:18 +0100
          Re: how to avoid leading white spaces Gregory Ewing <greg.ewing@canterbury.ac.nz> - 2011-06-04 13:41 +1200
            Re: how to avoid leading white spaces Nobody <nobody@nowhere.com> - 2011-06-04 20:44 +0100
          Re: how to avoid leading white spaces Ian <hobson42@gmail.com> - 2011-06-06 22:04 +0100
            Re: how to avoid leading white spaces Chris Torek <nospam@torek.net> - 2011-06-09 02:32 +0000
        Re: how to avoid leading white spaces Thorsten Kampe <thorsten@thorstenkampe.de> - 2011-06-03 10:32 +0200
      Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-03 05:51 -0700
        Re: how to avoid leading white spaces Neil Cerutti <neilc@norwich.edu> - 2011-06-03 13:17 +0000
          Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-03 08:14 -0700
        Re: how to avoid leading white spaces Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-03 14:25 +0000
          Re: how to avoid leading white spaces "D'Arcy J.M. Cain" <darcy@druid.net> - 2011-06-03 10:58 -0400
          Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-03 12:29 -0700
            Re: how to avoid leading white spaces Neil Cerutti <neilc@norwich.edu> - 2011-06-03 20:49 +0000
              Re: how to avoid leading white spaces Chris Torek <nospam@torek.net> - 2011-06-03 21:45 +0000
                Re: how to avoid leading white spaces Ethan Furman <ethan@stoneleaf.us> - 2011-06-03 15:11 -0700
                Re: how to avoid leading white spaces MRAB <python@mrabarnett.plus.com> - 2011-06-03 23:38 +0100
                Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-05 22:47 -0700
              Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-05 22:44 -0700
                Re: how to avoid leading white spaces Neil Cerutti <neilc@norwich.edu> - 2011-06-06 16:08 +0000
                Re: how to avoid leading white spaces Ian Kelly <ian.g.kelly@gmail.com> - 2011-06-06 10:29 -0600
                Re: how to avoid leading white spaces Neil Cerutti <neilc@norwich.edu> - 2011-06-06 17:17 +0000
                Re: how to avoid leading white spaces Ian Kelly <ian.g.kelly@gmail.com> - 2011-06-06 11:40 -0600
                Re: how to avoid leading white spaces Neil Cerutti <neilc@norwich.edu> - 2011-06-06 17:56 +0000
                Re: how to avoid leading white spaces Ethan Furman <ethan@stoneleaf.us> - 2011-06-06 10:48 -0700
                Re: how to avoid leading white spaces Ian Kelly <ian.g.kelly@gmail.com> - 2011-06-06 11:42 -0600
            Re: how to avoid leading white spaces Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-04 02:05 +0000
              Re: how to avoid leading white spaces MRAB <python@mrabarnett.plus.com> - 2011-06-04 03:24 +0100
                Re: how to avoid leading white spaces Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-04 04:59 +0000
              Re: how to avoid leading white spaces Roy Smith <roy@panix.com> - 2011-06-03 22:30 -0400
                Re: how to avoid leading white spaces Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-04 05:14 +0000
                Re: how to avoid leading white spaces Roy Smith <roy@panix.com> - 2011-06-04 09:39 -0400
                Re: how to avoid leading white spaces Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-05 00:44 +0000
                Re: how to avoid leading white spaces rusi <rustompmody@gmail.com> - 2011-06-04 09:36 -0700
                Re: how to avoid leading white spaces Nobody <nobody@nowhere.com> - 2011-06-04 21:02 +0100
                Re: how to avoid leading white spaces Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-05 01:01 +0000
                Re: how to avoid leading white spaces Chris Angelico <rosuav@gmail.com> - 2011-06-04 16:04 +1000
              Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-05 23:03 -0700
                Re: how to avoid leading white spaces Chris Torek <nospam@torek.net> - 2011-06-06 07:11 +0000
                Re: how to avoid leading white spaces "Octavian Rasnita" <orasnita@gmail.com> - 2011-06-06 11:51 +0300
                Re: how to avoid leading white spaces Chris Angelico <rosuav@gmail.com> - 2011-06-06 19:01 +1000
                Re: how to avoid leading white spaces rusi <rustompmody@gmail.com> - 2011-06-06 07:33 -0700
                Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-07 11:37 -0700
                Re: how to avoid leading white spaces Roy Smith <roy@panix.com> - 2011-06-07 20:30 -0400
                Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-08 07:38 -0700
                Re: how to avoid leading white spaces rusi <rustompmody@gmail.com> - 2011-06-08 09:14 -0700
                Re: how to avoid leading white spaces rusi <rustompmody@gmail.com> - 2011-06-08 01:27 -0700
                Re: how to avoid leading white spaces Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-06-06 15:29 +0000
                Re: how to avoid leading white spaces Ian Kelly <ian.g.kelly@gmail.com> - 2011-06-06 10:06 -0600
                Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-07 09:00 -0700
                Re: how to avoid leading white spaces Duncan Booth <duncan.booth@invalid.invalid> - 2011-06-08 09:01 +0000
                Re: how to avoid leading white spaces "rurpy@yahoo.com" <rurpy@yahoo.com> - 2011-06-08 07:39 -0700
          Re: how to avoid leading white spaces rusi <rustompmody@gmail.com> - 2011-06-05 04:17 -0700

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