//???????
TPt<TNodeEDatNet<TFlt, TFlt>> GenerateDAG2(const TPt<TNodeEDatNet<TFlt, TFlt>>& pGraph, const std::vector<int> &vSeedIDs, double dThreshold)
{
// Vector of MIOA graphs per seed node
std::vector<TPt<TNodeEDatNet<TFlt, TFlt>>> vMIOAGraphs;
// Compute the union of MIOA for each node of vSeedIDs
for(auto it=vSeedIDs.begin(); it!=vSeedIDs.end(); ++it)
vMIOAGraphs.push_back(MIOA(pGraph, *it, dThreshold));
auto pOut = GraphUnion(vMIOAGraphs);
// Set node data
for (auto NI = pOut->BegNI(); NI < pOut->EndNI(); NI++)
pOut->SetNDat(NI.GetId(), FLT_MAX);
// Copy the edge weights from pGraph
for (auto EI = pOut->BegEI(); EI < pOut->EndEI(); EI++)
pOut->SetEDat(EI.GetSrcNId(), EI.GetDstNId(), pGraph->GetEDat(EI.GetSrcNId(), EI.GetDstNId()));
// Create a super root in order to update in one pass all the shortest paths from vSeedIDs nodes
int superRootID = pGraph->GetMxNId()+1;
pOut->AddNode(superRootID);
for(auto it=vSeedIDs.begin(); it!=vSeedIDs.end(); ++it)
{
pOut->AddEdge(superRootID, *it);
pOut->SetEDat(superRootID, *it, 1.0);
}
Dijkstra(pOut, superRootID, dThreshold, pOut);
// Remove the artificial super root node
pOut->DelNode(superRootID);
// Traverse the edges and prune the graph
for (auto EI = pOut->BegEI(); EI < pOut->EndEI(); EI++)
{
if(EI.GetDstNDat().Val < EI.GetSrcNDat().Val)
pOut->DelEdge(EI.GetSrcNId(), EI.GetDstNId());
}
//Reset Node data from the original graph
for (auto NI = pGraph->BegNI(); NI < pGraph->EndNI(); NI++)
pOut->SetNDat(NI.GetId(),NI.GetDat().Val);
return pOut;
}
std::vector<int> MaxIncrementalInfluence(TPt<TNodeEDatNet<TFlt, TFlt>>& pGraph, int numRounds){
std::vector<int> vSeedSet;
tbb::concurrent_unordered_map<int,double> mSpreadIncrement;
auto pGraph_temp = TNodeEDatNet<TFlt, TFlt>::New();
double influence = 0.0; int i,chunk = 50;
static tbb::spin_mutex sMutex;
//Failure of using PeerSeeds due to insufficient memory
//std::map<int,std::vector<int> > mPeerSeeds;
//std::map<int,TPt<TNodeEDatNet<TFlt, TFlt>> > mMIOAs;
/* Initialization*/
int numNodes = pGraph->GetMxNId();
#pragma omp parallel shared(pGraph,chunk,mSpreadIncrement) private(pGraph_temp,i)
{
#pragma omp for schedule(dynamic,chunk) nowait
for (i =0;i<numNodes;++i)
{
if(pGraph->IsNode(i))
{
pGraph_temp = MIOA(pGraph, i, 0);
InitializationBeforePropagation(pGraph_temp);
ParallelBPFromNode_1DPartitioning(pGraph_temp, i);
mSpreadIncrement[i]=InfluenceSpreadFromSeedNodes(pGraph_temp);
//mMIOAs.insert(std::make_pair(i,pGraph_v));
}
}
}
/*
//build PeerSeeds
//Failure due to the insufficient memory
for (int v =0; v<pGraph->GetNodes();++v)
if(pGraph->IsNode(v))
mPeerSeeds[v]=GetPeerSeeds(mMIOAs,v);
*/
cout<<"--------------------------Finished Initialization---------------------"<<endl;
for (int i=0;i<numRounds;++i)
{
/* select the i'th seed by finding u = argmax(mSpreadIncrement)*/
auto it = std::max_element(mSpreadIncrement.begin(),mSpreadIncrement.end(),
[&](std::pair<int,double> const& a, std::pair<int,double> const& b) {
return a.second < b.second;
}
);
int SeedID = it->first;
cout << SeedID <<endl;
/* calculate the current influence spread */
vSeedSet.push_back(SeedID);
pGraph = GenerateDAG1(pGraph, vSeedSet, 0.0);
ParallelBPFromNode_1DPartitioning(pGraph, vSeedSet);
influence = InfluenceSpreadFromSeedNodes(pGraph);
/*remove the newly selected node*/
mSpreadIncrement.unsafe_erase(SeedID);
/* update incremental influence spread for each round */
double Delta_MAX = 0.0;
std::vector<int> vSeedSet_temp = vSeedSet;
#pragma omp parallel shared(pGraph,chunk,vSeedSet,mSpreadIncrement,Delta_MAX) private(pGraph_temp,vSeedSet_temp,i)
{
#pragma omp for schedule(dynamic,chunk) nowait
for (i =0;i<numNodes;++i)
{
/* exclude the nodes in seed set */
auto result = std::find(vSeedSet.begin(),vSeedSet.end(), i);
if (result != vSeedSet.end()) continue;
if(pGraph->IsNode(i) && mSpreadIncrement[i] > Delta_MAX)
{
/*different processors use different copied vSeedSet*/
vSeedSet_temp.push_back(i);
pGraph_temp = GenerateDAG1(pGraph, vSeedSet_temp, 0);
ParallelBPFromNode_1DPartitioning(pGraph_temp, vSeedSet_temp);
mSpreadIncrement[i]=InfluenceSpreadFromSeedNodes(pGraph_temp)-influence;
if (mSpreadIncrement[i]> Delta_MAX)
{
tbb::spin_mutex::scoped_lock lock(sMutex);
Delta_MAX = mSpreadIncrement[i];
}
vSeedSet_temp.pop_back();
}
}
}
}
return vSeedSet;
}