Re: substrings that consist of repeating characters

The simplest way to do it, demonstrated in the debugger

  DB<39> $_ = "AAATTTAGTTCTTAAGGCTGACATCGGTTTACGTCAGCGTTACCCCCCAAGTTAT
+TGGGGACTTT";

  DB<40> push @substr, $1 while /((\w)\2+)/g

  DB<41> @sorted = sort { length($b) <=> length($a) } @substr

  DB<42> x @sorted
0  'CCCCCC'
1  'GGGG'
2  'AAA'
3  'TTT'
4  'TTT'
5  'TTT'
6  'TT'
7  'TT'
8  'AA'
9  'GG'
10  'GG'
11  'TT'
12  'AA'
13  'TT'
14  'TT'
  DB<43>
[download]

Storing the length in @substr for a Schwartzian transform might be faster, but I wouldn't bet on this.

IMHO is length only doing a simple lookup of the pre-calculated length inside Perl's data-structure for strings and should be pretty fast.

HTH! :)

Cheers Rolf
_{(addicted to the Perl Programming Language :)

Wikisyntax for the Monastery}

update

you could also do sort and dump in one line:

  DB<43> print join "\n", sort { length($b)<=>length($a) } @substr
CCCCCC
GGGG
AAA
TTT
TTT
TTT
TT
TT
AA
GG
GG
TT
AA
TT
TT
  DB<44>
[download]

Comment on Re: substrings that consist of repeating characters Select or Download Code

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Re^2: substrings that consist of repeating characters
by BillKSmith (Monsignor) on Sep 28, 2020 at 22:38 UTC

List::UtilsBy

use strict;
use warnings;
use List::UtilsBy::XS qw(nsort_by);

my $string = "AAATTTAGTTCTTAAGGCTGACATCGGTTTACGTCAGCGTTACCCCCCAAGTTATT
+GGGGACTTT";
my @matches;
push @matches, $& while ($string=~m/([AGCT])\1+/g);
local $, = "\n";
print nsort_by {length} @matches ;
[download]

Bill

[reply]
[d/l]


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