[ruby-talk:6646] RE: Array Intersect (&) question

Ross asked something about widely known and largely ignored language (on
this mailing list :)

> I have many uses for the Set Intersection operator on Arrays, 
> but while I wait for Ruby to be installed on my production 
> systems, can someone please suggest an implementation of this in Perl.

I'm not completely sure this is what you were after, but here it is anyway.
My machine responds nicely to this query of "search intersection from FAQ".

Actually the answer is so nice, that I wonder if Ruby community, or more
like the environment, should pick something from this.

	- Aleksi


$ perldoc -q intersection
=head1 Found in /usr/lib/perl5/5.00503/pod/perlfaq4.pod

=head2 How do I compute the difference of two arrays?  How do I compute the
inte
rsection of two arrays?

Use a hash.  Here's code to do both and more.  It assumes that
each element is unique in a given array:

    @union = @intersection = @difference = ();
    %count = ();
    foreach $element (@array1, @array2) { $count{$element}++ }
    foreach $element (keys %count) {
        push @union, $element;
        push @{ $count{$element} > 1 ? \@intersection : \@difference },
$element
;
    }