Re^4: How do you find duplicates in a string?


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Re^4: How do you find duplicates in a string?

by davido (Cardinal)

on Sep 21, 2006 at 18:50 UTC ( [id://574227]=note: print w/replies, xml )

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in reply to Re^3: How do you find duplicates in a string?
in thread How do you find duplicates in a string?

The hash approach is better for that, but I went ahead and re-implemented the regexp approach again anyway, just in case someone is interested in a pattern matching solution rather than an 'equal key' solution.

If you wanted to continue with the regexp approach, this solution will count the number of duplicate words. I modified the RE a little so that it would count "Antony Antony Antony" as two duplicates (Antony is repeated twice after the original). "Antony Antony Hank Antony Hank Mark" would count 3: Antony has two repeats, and Hank has one.

use warnings;
use strict;

my $string='LOCAL    Antony    17    Antony    23    1569';

my $count;
$count++ while
    $string =~ m/
                  \b([[:alpha:]]+)\b
                  (?=.*?\b\1\b)
                /xg;

print $count, "\n";
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Dave