private void PartialBetweenessComp()
{
int numIndices = _work.Length;
int numNodes = _g.NumNodes;
double[] delta = new double[numNodes];
for (int i = 0; i < numIndices; i++)
{
int v = _work[i];
//Get a shortest path, if weighted use Dikstra, if unweighted use BFS
ShortestPathProvider asp = (_g.IsWeighted) ? new DikstraProvider2(_g, v) :
new BFSProvider(_g, v) as ShortestPathProvider;
for (int j = 0; j < numNodes; j++)
{
delta[j] = 0.0f;
}
while (asp.S.Count > 0)
{
int w = asp.S.Pop();
var wList = asp.fromList[w];
foreach (int n in wList)
{
delta[n] += ((double)asp.numberOfShortestPaths[n] / (double)asp.numberOfShortestPaths[w]) * (1.0f + delta[w]);
}
if (w != v)
{
BcMap[w] += delta[w];
}
}
}
}
/// <summary>
/// Calculates Betweeness centrality of the edges in an undirected graph
/// </summary>
/// <param name="g"></param>
/// <returns></returns>
public static NodeEdgeBetweeness BrandesBcEdges(LightWeightGraph g)
{
var edgeMap = g.GetEdgeIndexMap();
int numNodes = g.NumNodes;
int numEdges = edgeMap.Count;
double[] bcEdge = new double[numEdges];
double[] bcNode = new double[numNodes];
for (int v = 0; v < numNodes; v++)
{
//Get a shortest path, if weighted use Dikstra, if unweighted use BFS
ShortestPathProvider asp = (g.IsWeighted) ? new DikstraProvider2(g, v) :
new BFSProvider(g, v) as ShortestPathProvider;
//numberOfShortestPaths = sigma
double[] deltaNode = new double[numNodes];
while (asp.S.Count > 0)
{
int w = asp.S.Pop();
double coeff = (1.0f + deltaNode[w]) / (double)asp.numberOfShortestPaths[w];
foreach (int n in asp.fromList[w])
{
//make sure the first index is the smallest, this is an undirected graph
KeyValuePair <int, int> edgeNodePair = (w < n)
? new KeyValuePair <int, int>(w, n)
: new KeyValuePair <int, int>(n, w);
int edgeIndex = edgeMap[edgeNodePair];
double contribution = asp.numberOfShortestPaths[n] * coeff;
bcEdge[edgeIndex] += contribution;
deltaNode[n] += contribution;
}
//Add the betweeness contribution to W
if (v != w)
{
bcNode[w] += deltaNode[w];
}
}
}
//divide all by 2 (undirected)
for (int v = 0; v < numEdges; v++)
{
bcEdge[v] /= 2f;
}
for (int v = 0; v < numNodes; v++)
{
bcNode[v] /= 2f;
}
return(new NodeEdgeBetweeness()
{
EdgeBetweeness = bcEdge, NodeBetweeness = bcNode
});
}
private void PartialBetweenessComp()
{
for (int i = 0; i < delta.Length; i++)
{
delta[i] = 0;
}
//Get a shortest path, if weighted use Dikstra, if unweighted use BFS
ShortestPathProvider asp = (_g.IsWeighted)
? new DikstraProvider2(_g, v)
: new BFSProvider(_g, v) as ShortestPathProvider;
while (asp.S.Count > 0)
{
int w = asp.S.Pop();
var wList = asp.fromList[w];
foreach (int n in wList)
{
delta[n] += ((double)asp.numberOfShortestPaths[n] / asp.numberOfShortestPaths[w]) *
(1.0f + delta[w]);
}
}
delta[v] = 0;
}
public static double[] BrandesBcNodes(LightWeightGraph g)
{
int numnodes = g.NumNodes;
double[] bcMap = new double[numnodes];
double[] delta = new double[numnodes];
for (int v = 0; v < numnodes; v++)
{
//Get a shortest path, if weighted use Dikstra, if unweighted use BFS
ShortestPathProvider asp = (g.IsWeighted) ? new DikstraProvider2(g, v) :
new BFSProvider(g, v) as ShortestPathProvider;
Array.Clear(delta, 0, numnodes);
while (asp.S.Count > 0)
{
int w = asp.S.Pop();
var wList = asp.fromList[w];
foreach (int n in wList)
{
delta[n] += ((double)asp.numberOfShortestPaths[n] / (double)asp.numberOfShortestPaths[w]) * (1.0f + delta[w]);
}
if (w != v)
{
bcMap[w] += delta[w];
}
}
}
//divide all by 2 (undirected)
for (int v = 0; v < numnodes; v++)
{
bcMap[v] /= 2f;
}
return(bcMap);
}
