Hi all,

I'm doing graph traversal and calculating the Jaccard distance on each pair of vertices. Calculating intersection and union are consuming 98% of my processing time.

I've tried Set::IntSpan, Set::Array and List::Compare, but they are all even slower than my own code. Is there a VERY fast (maybe implemented in C) way to calculate intersection and union on two arrays? Just for interest, my implementation is ($in and $jn are array refs of positive integers): 

sub get_int_uni {

        my ($in, $jn) = @_;
        
        my (%int, %uni);
        for my $i (@$in) {
                $uni{$i}++;
        }
        for my $j (@$jn) {
                $int{$j}++ if $uni{$j};
                $uni{$j}++;
        }
        return ((scalar keys %int), (scalar keys %uni));
}

In reply to Fast, Efficient Union and Intersection on arrays by barvin

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