/// <summary>
/// Calculate page rank for graph
/// </summary>
/// <param name="graph">Source graph</param>
/// <param name="d">Damping factor</param>
/// <returns>Calculated page rank</returns>
public static PageRankResult CalculatePageRank(this IPageRankGraph graph, double d = 0.85)
{
var pageRank = new Dictionary <uint, double>();
var pageRankNext = new Dictionary <uint, double>();
double initPr = 1.0 / graph.NodesCount;
// 1
foreach (var node in graph)
{
pageRankNext[node.Key] = (1 - d) / graph.NodesCount + d * node.Parents.Sum(x => initPr / x.NumberOfEdges);
}
// 2
foreach (var node in graph)
{
pageRank[node.Key] = (1 - d) / graph.NodesCount + d * node.Parents.Sum(x => pageRankNext[x.Key] / x.NumberOfEdges);
}
return(new PageRankResult(pageRank));
}
/// <summary>
/// Calculate page rank for graph
/// </summary>
/// <param name="graph">Source graph</param>
/// <param name="d">Damping factor</param>
/// <returns>Calculated page rank</returns>
public static PageRankResult PageRank(this IPageRankGraph graph, double d = 0.85)
{
var pageRank = new Dictionary <uint, double>();
var pageRankNext = new Dictionary <uint, double>();
double initPr = 1.0 / graph.NodesCount;
// 1
foreach (var node in graph)
{
pageRankNext[node] = (1 - d) / graph.NodesCount + d * graph.Parents(node).Sum(x => initPr / graph.EdgesCount(x));
}
// 2
foreach (var node in graph)
{
pageRank[node] = (1 - d) / graph.NodesCount + d * graph.Parents(node).Sum(x => pageRankNext[x] / graph.EdgesCount(x));
}
return(new PageRankResult(pageRank));
}
