Re: 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'
[download]

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]

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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;` [download] Outputs: `("given ZBBBCZZ got", ["Z", "BBB", "C", "ZZ"])` [download]	[reply] [d/l] [select]
Re^3: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) (forget captures ) by LanX (Saint) on Oct 20, 2021 at 23:44 UTC
> a way to "forget" the group... Ha! Someone already found a generic solution 14 years ago....:) > Re^6: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) (??{}) `DB<1> x "ZBBCZZ" =~ /(??{'(.)\1*'})/g; 0 'Z' 1 'BB' 2 'C' 3 'ZZ' DB<2>` [download] Brillant! :) Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply] [d/l]
Re^4: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) by eyepopslikeamosquito (Archbishop) on Oct 21, 2021 at 01:01 UTC
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. :)	[reply]
Re^5: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) by LanX (Saint) on Oct 21, 2021 at 04:09 UTC
Re^3: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) by LanX (Saint) on Oct 20, 2021 at 16:28 UTC
well thanks, ~~but it's destructive ...~~ YOU can do better! ;-) Cheers Rolf _{(addicted to the Perl Programming Language :) Wikisyntax for the Monastery}	[reply]
Re^4: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) by tybalt89 (Monsignor) on Oct 20, 2021 at 17:27 UTC
No, it's not. The output even shows it is not. ("given ZBBBCZZ got", "Z", "BBB", "C", "ZZ")	[reply]
Re^5: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) by LanX (Saint) on Oct 20, 2021 at 17:40 UTC
Re^6: Yet Another Rosetta Code Problem (Perl, Ruby, Python, Haskell, ...) by Tux (Canon) on Oct 21, 2021 at 08:51 UTC


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