File Coverage

blib/lib/Graph/Maker/Petersen.pm

Criterion	Covered	Total	%
statement	6	8	75.0
branch			n/a
condition			n/a
subroutine	3	3	100.0
pod			n/a
total	9	11	81.8

# Copyright 2015, 2016, 2017 Kevin Ryde
#
# This file is part of Graph-Maker-Other.
#
# This file is free software; you can redistribute it and/or modify it
# under the terms of the GNU General Public License as published by the Free
# Software Foundation; either version 3, or (at your option) any later
# version.
#
# This file is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
# for more details.
#
# You should have received a copy of the GNU General Public License along
# with Graph-Maker-Other.  See the file COPYING.  If not, see
# .

package Graph::Maker::Petersen;
use 5.004;
use strict;
use Graph::Maker;

use vars '$VERSION','@ISA';
$VERSION = 7;
@ISA = ('Graph::Maker');


sub _default_graph_maker {
  require Graph;
  return Graph->new(@_);
}
sub _make_graph {
  my ($params) = @_;
  my $graph_maker = delete($params->{'graph_maker'}) || \&_default_graph_maker;
  return $graph_maker->(%$params);
}

sub init {
  my ($self, %params) = @_;

  my $N = delete($params{'N'}) || 5;
  my $K = delete($params{'K'}) || 2;

  my $graph = _make_graph(\%params);
  $graph->set_graph_attribute (name => ($N==5 && $K==2 ? "Petersen" : "Petersen $N,$K"));

  $graph->add_cycle(1 .. $N);
  foreach my $i (1 .. $N) {
    my $j = $i + $N;
    my $f = $N+1 + (($i-1+$K) % $N);
    if ($f > 2*$N) { $f -= $N; }
    $graph->add_edges([$i,$j],[$j,$f]);
  }

  # $graph->add_cycle(1,2,3,4,5);
  # $graph->add_cycle(6,8,10,7,9);
  # $graph->add_edges([1,6],[2,7],[3,8],[4,9],[5,10]);

  if ($graph->is_directed) {
    $graph->add_edges(map {[reverse @$_]} $graph->edges);
  }
  return $graph;
}

Graph::Maker->add_factory_type('Petersen' => __PACKAGE__);
1;

__END__