Hi can you help please? I am new to perl and i'm trying to run the code below to calculate the shortest path using Floyd-Warshall algorithm. The code is directly copied from "Mastering algorithm with perl" from O'Reilliy media. The problem is when i run the code i don't get any results and i get the following message "get_attribute: not a compat02 graph ". Am i missing a module? Can anyone help please? thanks in advance. filipo. 

#!/usr/bin/perl -w

use strict;
use Graph; 
use Graph::Directed;

#how to use the Floyd-Warshall code

my $g=Graph::Directed->new;

$g->add_weighted_path(qw(a 1 b 4 c 1 d));
$g->add_weighted_path(qw(a 3 f 1 e 2 d));
$g->add_weighted_edges(qw(a  c 2  a  d 4  b  e 2  f  d  2 ));
 
my $APSP = $g->APSP_Floyd_Warshall;

print "     ";
foreach my $v ($APSP->vertices ) { printf "%-9s ", "$v" } print "\n";
foreach my $u ($APSP-> vertices ) {
    print "$u: ";
    foreach my $v ( $APSP->vertices ) {
        my $w = $APSP->get_attribute("weight", $u, $v);
        
        if (defined $w) {
            my $p = $APSP->get_attribute("path",  $u, $v);
            
            printf "(%-5s)=%d ", "@$p", $w
        } else {
            printf "%-9s ", "-"
        }
    }
    print "\n"
}

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In reply to calculating shortest path using Floyd-Warshall with perl by filipo

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