OT: regular expression matching multiple occurrences of one group

[pinkisntwell]

How can I make a regular expression that will match every occurrence
of a group and return each occurrence as a group match? For example,
for a string "-c-c-c-c-c", how can I make a regex which will return a
group match for each occurrence of "-c"?
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Re: OT: regular expression matching multiple occurrences of one group

[Diez B. Roggisch]

pinkisntwell schrieb:

How can I make a regular expression that will match every occurrence
of a group and return each occurrence as a group match? For example,
for a string "-c-c-c-c-c", how can I make a regex which will return a
group match for each occurrence of "-c"?


Why is this flagged "OT"?

And in python, you can't do that. Groups are based upon the lexical 
structure of the regexp, and thus have a fixed number of groups.


Either use repetitive searches over the input, or postprocess the 
combined group by e.g. splitting it.


Diez
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Re: OT: regular expression matching multiple occurrences of one group

[Jon Clements]

On Nov 9, 1:53 pm, pinkisntwell  wrote:
> How can I make a regular expression that will match every occurrence
> of a group and return each occurrence as a group match? For example,
> for a string "-c-c-c-c-c", how can I make a regex which will return a
> group match for each occurrence of "-c"?

As well as what Diez has said, unless you absolutely want regexp's,
and by the sounds of it I'm guessing you may be after something more
flexible: what about the pyparsing module [1]. It handles your
situation quite nicely.

>>> import pyparsing
>>> parser = pyparsing.ZeroOrMore('-c')
>>> parser.parseString('-c-c-c-c-c-c')
(['-c', '-c', '-c', '-c', '-c', '-c'], {})

hth,
Jon.


[1] http://pyparsing.wikispaces.com/
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Re: OT: regular expression matching multiple occurrences of one group

[sln]

On Mon, 9 Nov 2009 05:53:00 -0800 (PST), pinkisntwell  
wrote:

>How can I make a regular expression that will match every occurrence
>of a group and return each occurrence as a group match? For example,
>for a string "-c-c-c-c-c", how can I make a regex which will return a
>group match for each occurrence of "-c"?

Is this a ludicrous question, or is it meant for the python group?

use strict;
use warnings;

my @matches = "-c-c-c-c-c" =~ /(-c)/g;
print "\...@matches\n";

@matches = ();
"-c-a-c-c-c" =~ /(?:(-c)(?{push @matches, $^N})|.)+/x;
print "@matches\n";

-sln
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Re: OT: regular expression matching multiple occurrences of one group

[J�rgen Exner]

pinkisntwell  wrote:
>How can I make a regular expression that will match every occurrence
>of a group and return each occurrence as a group match? For example,
>for a string "-c-c-c-c-c", how can I make a regex which will return a
>group match for each occurrence of "-c"?

Where is the problem? The most straight-forward, simplest approach works
just fine:
use strict; use warnings;
my $s = '-c-c-c-c-c';

my @matched = $s=~/-c/g;

print "Found ". @matched . " occurences of '-c':\n";
print join "\n", @matched;

Or did you forget to use the g modifier?

jue
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Re: OT: regular expression matching multiple occurrences of one group

[Gabriel Genellina]

En Mon, 09 Nov 2009 12:59:53 -0300, Jon Clements   
escribió:

On Nov 9, 1:53 pm, pinkisntwell  wrote:



How can I make a regular expression that will match every occurrence
of a group and return each occurrence as a group match? For example,
for a string "-c-c-c-c-c", how can I make a regex which will return a
group match for each occurrence of "-c"?


As well as what Diez has said, unless you absolutely want regexp's,
and by the sounds of it I'm guessing you may be after something more
flexible: what about the pyparsing module [1]. It handles your
situation quite nicely.


import pyparsing
parser = pyparsing.ZeroOrMore('-c')
parser.parseString('-c-c-c-c-c-c')

(['-c', '-c', '-c', '-c', '-c', '-c'], {})


Not that I like regexes very much, but findall does exactly that:

py> re.findall('-c', '-c-c-c-c-c-c')
['-c', '-c', '-c', '-c', '-c', '-c']

Now, the OP said "return each occurrence as a group match":

py> for g in re.finditer("-c", '-c-c-c-c-c-c'): print g, g.span(),  
g.group()

...
<_sre.SRE_Match object at 0x00C096E8> (0, 2) -c
<_sre.SRE_Match object at 0x00C09410> (2, 4) -c
<_sre.SRE_Match object at 0x00C096E8> (4, 6) -c
<_sre.SRE_Match object at 0x00C09410> (6, 8) -c
<_sre.SRE_Match object at 0x00C096E8> (8, 10) -c
<_sre.SRE_Match object at 0x00C09410> (10, 12) -c

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Gabriel Genellina

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