A better title for the OP's question would be "Finding all connected nodes in a directed graph". From the "members and partners" language, I'd guess that this is for something like a friend-of-a-friend networking tool

I'm not entirely sure what "extend the hash" means, but I think you might be well served by looking at the Graph::Base distribution.

Building the all-pairs shortest-path network might seem like overkill, but if you can find a way to cache that and only rebuild it when the network changes, you should then be able to repeatedly pull out whichever subset you're interested in. 

  use Graph::Directed;
  my $network = Graph::Directed->new();

  # Build a directed network of partners and members
  foreach my $partner ( keys %partners ) {
    foreach my $item ( @{ $partners{$partner} ) {
      # Add each pairing as a network edge with weight 1
      $network->add_edge( $partner, $item );
      $network->set_attribute('weight', $partner, $item, 1);
    }
  }

  # Now build a shortest-path network
  my $friends = $network->APSP_Floyd_Warshall();

  # Now review all of the links in the network
  my $required_level = 2;
  my ( @all_levels ) = $friends->edges();
  while ( scalar @all_levels ) {
    my ( $from, $to ) = splice(@all_levels, 0, 2);
    my $degrees = $friends->get_attribute('weight', $from, $to);
    next if ( $degrees > $required_level );
    push @{ $allmembers{$from} }, $to;
  }

[download]

At a minimum, take a look at the implementation of APSP_Floyd_Warshall, which seems to be related to what you're looking for.

I'm hardly a graph-theory expert, so the above might not really be what the OP was asking for... corrections would be welcome. I just knew that there must be an existing implementation for this and searched CPAN for Graph.

In reply to Re: creating a hash of arrays/hashes by simonm
in thread creating a hash of arrays/hashes by jonnyfolk

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