Graph-Centrality-Pagerank

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README  view on Meta::CPAN

        permitted between successive pagerank vectors before the iterative
        process to approximate the pagerank vector should be stopped. The
        default is the square root of the systems machine epsilon. Usually,
        most pagerank values computed will have "-log10(maxRelError)" digits
        of accuracy. "maxRelError" must be positive and less than or equal
        to 0.01.

    "minIterations"
         minIterations => 0

        "minIterations" is the minimum number of iterations that will be
        computed before the pagerank iterations are stopped, even if
        "maxRelError" is achieved. The default is zero.

    "maxIterations"
         maxIterations => int (2 * ((maxRelError / ln (dampeningFactor) + 1))

        "maxIterations" is the maximum number of iterations that can be
        performed to approximate the pagerank vector even if "maxRelError"
        is not achieved. The default is "2 * ((maxRelError / ln
        (dampeningFactor) + 1)". If "dampeningFactor" is zero, then
        "maxIterations" is one. If "dampeningFactor" is one, then
        "maxIterations" is equal to the total nodes in the graph.

    "linkSinkNodes"
         linkSinkNodes => 1

        In a directed graph sink nodes are the nodes with no edges emanating

lib/Graph/Centrality/Pagerank.pm  view on Meta::CPAN

C<maxRelError> is the maximum I<average> relative error that is permitted between
successive pagerank vectors before the iterative process to approximate the pagerank vector
should be stopped. The default is the square root of the systems machine epsilon.
Usually, most pagerank values computed will have C<-log10(maxRelError)> digits of accuracy.
C<maxRelError> must be positive and less than or equal to 0.01.

=item C<minIterations>

 minIterations => 0

C<minIterations> is the minimum number of iterations that will be computed
before the pagerank iterations are stopped, even if C<maxRelError> is achieved.
The default is zero.

=item C<maxIterations>

 maxIterations => int (2 * ((maxRelError / ln (dampeningFactor) + 1))

C<maxIterations> is the maximum number of iterations that can be performed
to approximate the pagerank vector even if C<maxRelError> is not achieved.
The default is C<2 * ((maxRelError / ln (dampeningFactor) + 1)>. If
C<dampeningFactor> is zero, then C<maxIterations> is one. If C<dampeningFactor>
is one, then C<maxIterations> is equal to the total nodes in the graph.

=item C<linkSinkNodes>

 linkSinkNodes => 1

In a directed graph sink nodes are the nodes with no edges emanating out

lib/Graph/Centrality/Pagerank.pm  view on Meta::CPAN

  # set dampening factor, default is .85;
  $Parameters{dampeningFactor} = 0.85 unless (exists ($Parameters{dampeningFactor}));
  $Parameters{dampeningFactor} = abs ($Parameters{dampeningFactor}) if (exists ($Parameters{dampeningFactor}));
  $Parameters{dampeningFactor} = 1 if ($Parameters{dampeningFactor} > 1);

  # set max relative error, default is sqrt (machine epsilon).
  $Parameters{maxRelError} = sqrt ($Self->_getMachineEpsilon ()) unless (exists ($Parameters{maxRelError}));
  $Parameters{maxRelError} = abs ($Parameters{maxRelError}) if (exists ($Parameters{maxRelError}));
  $Parameters{maxRelError} = 0.01 if ($Parameters{maxRelError} > 0.01);

  # set default min iterations.
  $Parameters{minIterations} = 1 unless (exists ($Parameters{minIterations}));
  $Parameters{minIterations} = abs ($Parameters{minIterations});

  # set default max iterations.
  unless (exists ($Parameters{maxIterations}))
  {
    $Parameters{maxIterations} = 1;
    $Parameters{maxIterations} = 1 if ($Parameters{dampeningFactor} <= 0);
    $Parameters{maxIterationsIsTotalNodes} = 1 if ($Parameters{dampeningFactor} >= 1);
    if ($Parameters{dampeningFactor} < 1)
    {
      $Parameters{maxIterations} = 2 * (int (log ($Parameters{maxRelError}) / log ($Parameters{dampeningFactor})) + 1);
    }
  }

lib/Graph/Centrality/Pagerank.pm  view on Meta::CPAN

  # set dampening factor.
  $Parameters{dampeningFactor} = $Self->{defaultParameters}{dampeningFactor} unless (exists ($Parameters{dampeningFactor}));
  $Parameters{dampeningFactor} = abs ($Parameters{dampeningFactor}) if (exists ($Parameters{dampeningFactor}));
  $Parameters{dampeningFactor} = 1 if ($Parameters{dampeningFactor} > 1);

  # set max relative error.
  $Parameters{maxRelError} = $Self->{defaultParameters}{maxRelError} unless (exists ($Parameters{maxRelError}));
  $Parameters{maxRelError} = abs ($Parameters{maxRelError}) if (exists ($Parameters{maxRelError}));
  $Parameters{maxRelError} = 0.01 if ($Parameters{maxRelError} > 0.01);

  # set default min iterations.
  $Parameters{minIterations} = $Self->{defaultParameters}{minIterations} unless (exists ($Parameters{minIterations}));
  $Parameters{minIterations} = abs ($Parameters{minIterations});

  # set default max iterations.
  unless (exists ($Parameters{maxIterations}))
  {
    $Parameters{maxIterations} = $Self->{defaultParameters}{maxIterations};
    if ((0 < $Parameters{dampeningFactor}) && ($Parameters{dampeningFactor} < 1))
    {
      $Parameters{maxIterations} = 2 * (int (log ($Parameters{maxRelError}) / log ($Parameters{dampeningFactor})) + 1);
    }
  }
  $Parameters{maxIterations} = abs ($Parameters{maxIterations});
  $Parameters{maxIterations} = 1 if ($Parameters{maxIterations} < 1);

lib/Graph/Centrality/Pagerank.pm  view on Meta::CPAN

    foreach my $node (@allNodes) { $nodeWeights{$node} = 1 / $totalNodes; }
  }


  # initialize the pagerank vector;
  my $pagerank = {};
  return $pagerank if ($totalNodes == 0);
  foreach my $node (@allNodes) { $pagerank->{$node} = $nodeWeights{$node}; }
  my $newPageRank = {};

  # set the maximum number of iterations.
  my $maxIterations = $Parameters{maxIterations};
  $maxIterations = $totalNodes if exists $Parameters{maxIterationsIsTotalNodes};

  for (my $iteration = 0; $iteration < $maxIterations; $iteration++)
  {
    # first set the new page rank to the average pageranks times (1 - $dampeningFactor).
    if ($Parameters{scaleDampeningFactor})
    {
      #my $sum = 0;
      #foreach my $node (@allNodes) { $sum += $pagerank->{$node}; }