PUNGraph GenRndDegK(const int& Nodes, const int& NodeDeg, const int& NSwitch, TRnd& Rnd) {
// create degree sequence
TIntV DegV(Nodes, 0);
int DegSum=0;
for (int i = 0; i < Nodes; i++) {
DegV.Add(NodeDeg);
DegSum += NodeDeg;
}
IAssert(DegSum % 2 == 0);
PUNGraph G = GenDegSeq(DegV, Rnd); // get some graph that obeys the degree sequnce
return GenRewire(G, NSwitch, Rnd); // make it random
}
void TGraphKey::TakeSig(const PNGraph& Graph, const int& MnSvdGraph, const int& MxSvdGraph) {
const int Edges = Graph->GetEdges();
Nodes = Graph->GetNodes();
VariantId = 0;
SigV.Gen(2+Nodes, 0);
// degree sequence
TIntPrV DegV(Nodes, 0);
for (TNGraph::TNodeI NodeI = Graph->BegNI(); NodeI < Graph->EndNI(); NodeI++) {
DegV.Add(TIntPr(NodeI.GetInDeg(), NodeI.GetOutDeg()));
}
DegV.Sort(false);
SigV.Add(TFlt(Nodes));
SigV.Add(TFlt(Edges));
for (int i = 0; i < DegV.Len(); i++) {
SigV.Add(DegV[i].Val1());
SigV.Add(DegV[i].Val2());
}
// singular values signature
// it turns out that it is cheaper to do brute force isomorphism
// checking than to calculate SVD and then check isomorphism
if (Nodes >= MnSvdGraph && Nodes < MxSvdGraph) {
// perform full SVD
TFltVV AdjMtx(Nodes+1, Nodes+1);
TFltV SngValV;
TFltVV LSingV, RSingV;
TIntH NodeIdH;
// create adjecency matrix
for (TNGraph::TNodeI NodeI = Graph->BegNI(); NodeI < Graph->EndNI(); NodeI++) {
NodeIdH.AddKey(NodeI.GetId());
}
for (TNGraph::TNodeI NodeI = Graph->BegNI(); NodeI < Graph->EndNI(); NodeI++) {
const int NodeId = NodeIdH.GetKeyId(NodeI.GetId()) + 1;
for (int e = 0; e < NodeI.GetOutDeg(); e++) {
const int DstNId = NodeIdH.GetKeyId(NodeI.GetOutNId(e)) + 1; // no self edges
if (NodeId != DstNId) AdjMtx.At(NodeId, DstNId) = 1;
}
}
try { // can fail to converge but results seem to be good
TSvd::Svd(AdjMtx, LSingV, SngValV, RSingV);
} catch(...) {
printf("\n***No SVD convergence: G(%d, %d): SngValV.Len():%d\n", Nodes(), Graph->GetEdges(), SngValV.Len());
}
// round singular values
SngValV.Sort(false);
for (int i = 0; i < SngValV.Len(); i++) {
SigV.Add(TMath::Round(SngValV[i], RoundTo));
}
}
//printf("SIG:\n"); for (int i = 0; i < SigV.Len(); i++) { printf("\t%f\n", SigV[i]); }
SigV.Pack();
}
