in reply to Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...)

I was missing a split solution with lookbehind and lookahead here, so I wanted to add it.

(step by step demo with 'perl -de0')

  DB<134> p $in
ZBBBCZZ
  DB<135> x split /(?<=(.))(?!\1)/, $in
0  'Z'
1  'Z'
2  'BBB'
3  'B'
4  'C'
5  'C'
6  'ZZ'
7  'Z'

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Alas I couldn't find a way to "forget" the group needed for the backreference \1 °

But this could be turned into something more flexible by applying "pair" functions from List::Util (which were probably not available back then)

  DB<137> use List::Util qw/pairkeys pairvalues/

  DB<138> x pairkeys  split /(?<=(.))(?!\1)/, $in
0  'Z'
1  'BBB'
2  'C'
3  'ZZ'
  DB<139> x pairvalues  split /(?<=(.))(?!\1)/, $in
0  'Z'
1  'B'
2  'C'
3  'Z'
  DB<140>

[download]

Cheers Rolf
(addicted to the Perl Programming Language :)
Wikisyntax for the Monastery

°) but I didn't search long, what I found is /n modifier, to turn each (...) into (?:...) , but then \1 isn't usable anymore

Update

Tho shorter tye's solution without split fits better here

  DB<8> use List::Util qw/pairkeys/

  DB<9> $_='ZBBBCZZ'

  DB<10> x pairkeys /((.)\2*)/g
0  'Z'
1  'BBB'
2  'C'
3  'ZZ'
  DB<11>

[download]

Replies are listed 'Best First'.
Re^2: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...)
by tybalt89 (Monsignor) on Oct 20, 2021 at 16:21 UTC

    Here's a way to "forget" the group... 

    #!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11137799
use warnings;

$_='ZBBBCZZ';

my @list = split ' ', s/(.)\K(?!\1)/ /gr;
use Data::Dump 'dd'; dd "given $_ got", \@list;

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    Outputs: 

    ("given ZBBBCZZ got", ["Z", "BBB", "C", "ZZ"])

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        And I see pKai is from Erlangen - an easy 216.6 km scenic drive from Darmstadt. :)

        Nice necropost BTW.

        Update: Maybe you should try to hire pKai to replace your new Python guy. :)

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