#$Id$
Q. How can I make comparisons among more than two lists when I don't know in
advance how many lists I'll need to compare?
A. Write a subroutine which returns a reference to an array. In your
program, call that subroutine as needed. Push the array reference returned
onto a "list of lists" which is then passed to List::Compare->new().
Example: You have a function, get_random_integers(), which returns a
reference to a list of random integers between 0 and 9. The number of items
in the list is itself a random integer between 0 and 9.
sub get_random_integers {
my $listsize = int(rand(10)); # 0..9
my @list;
for (0 .. $listsize) {
push @list, int(rand(10));
}
return \@list;
}
You call get_random_integers a random number of times between 2 and 11. Why
2? Because List::Compare must compare at least two lists.
#!/usr/bin/perl
use strict;
use warnings;
use List::Compare;
use Data::Dumper;
$Data::Dumper::Indent = 0;
my $list_quantity = int(rand(10)) + 2; # must have >= 2 lists
my @lol;
for (0 .. $list_quantity) {
my $listref = get_random_integers();
print Dumper $listref;
print "\n";
push @lol, $listref;
}
my $lc = List::Compare->new(@lol);
my (@intersection, @union, @unique, @complement);
@intersection = $lc->get_intersection();
@union = $lc->get_union();
@unique = $lc->get_unique(0); # items unique to first list
@complement = $lc->get_complement(0); # items found in any list but first
print Dumper(\@intersection, \@union, \@unique, \@complement);
Just substitute your own list-generating function for get_random_integers() in
the example above. For production code, strip out all the calls to Data::Dumper.
Generated by dwww version 1.14 on Fri Jan 24 09:30:28 CET 2025.