Modified to include CPAN refs and an additional comment.

Hi,
For I just have one correction Sets A and B doesn't contain the same number of strings
Should read : Sets A and B may not contain the same number of strings

I use use Algorithm::Diff and that works approximately ok for my match-purpose.

Aritst

It's not obvious to me how Algorithm::Diff can be used to compute edit distances. Do you call diff() and then count up the number of insertions and deletions in the result?

Suppose you have several equidistant matches from a given element in A to several elements in B. Do you have to pick one of them such that the overall number of pairings is maximized? It might be an NP-complete problem.

I think you are right. Text::Levenshtein is better in this case because String::Approx will match substrings of the input. Here is one more thing. If substitutions are not allowed, only inserts and deletes, you could use Text::WagnerFischer to set the cost of substitution so high that it will not be used.

use Text::Levenshtein;
use Text::WagnerFischer;

my $pat = 'AAB';
my @lst = qw(ABAB ABBA ABB ABABAAB);
my @dist1 = Text::Levenshtein::distance($pat, @lst);
my @dist2 = Text::WagnerFischer::distance([0, 1, 100], $pat, @lst);

my ($i, $item);
$i = 0;
foreach $item (@lst) {
   print "Levenshtein distance of $item to $pat is ",$dist1[$i],"\n";
   print "WagnerFischer distance of $item to $pat is ",$dist2[$i],"\n"
+;
   $i++;
}
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