double scn::GetCyclicCoeff(UGraph::pGraph graph,size_t indexOfNode)
{
//IndexList edges;
std::pair<IndexList, IndexList> result;
std::unordered_map<size_t,size_t> distance;
//auto& distance = distance_sssp;
distance.clear();
if(indexOfNode != UGraph::NaF)
{//one vertex
result = graph->RemoveNode(indexOfNode);
IndexList& edges = result.first;
double sum = 0;
for(auto head = edges.begin(); head != edges.end(); head++)
{
RunSPFA(graph,*head,distance);
for(auto tail = head + 1; tail != edges.end(); tail++)
{
sum += 1.0 / static_cast<double>(distance[*tail] + 2);
}
}
///restore
graph->AddEdge(graph->AddNode(indexOfNode), edges);
return 2 * sum / static_cast<double>(edges.size() * (edges.size() - 1));
}
else
{//the whole network
//copy node list
IndexList nodes = graph->CopyIndexOfNodes();
double total_sum = 0;
for(auto node = nodes.begin(); node != nodes.end(); node++)
{
result = graph->RemoveNode(*node);
IndexList& edges = result.first;
double sum = 0;
for(auto head = edges.begin(); head != edges.end(); head++)
{
RunSPFA(graph,*head,distance);
for(auto tail = head + 1; tail != edges.end(); tail++)
{
sum += 1.0 / static_cast<double>(distance[*tail] + 2);
}
}
///restore, add node first, then add list of edges of this node
graph->AddEdge(graph->AddNode(*node), edges);
//accumulate
total_sum += 2 * sum / static_cast<double>(edges.size() * (edges.size() - 1));
}
return total_sum / static_cast<double>(graph->GetNumberOfNodes());
}
}
UGraph::pGraph scn::GenSmallWorldNetworkByNW(size_t numberOfNodes, size_t k,
double probability)
{
assert(2* k + 1 <= numberOfNodes);
assert(probability >= 0);
assert(probability <= 1);
//generate k-nearest network
UGraph::pGraph graph = GenKNearestNetwork(numberOfNodes, k);
//add edges randomly
size_t numberOfEdges = numberOfNodes * (numberOfNodes - 2 * k - 1) / 2 * probability;
size_t sum_edges = 0;
size_t one, two;
srand(size_t(time(00)));
do
{
one = rand() % numberOfNodes;
two = rand() % numberOfNodes;
if(!(one == two || graph->HasEdge(one, two)))
{
graph->AddEdge(one, two);
sum_edges++;
}
}while(sum_edges < numberOfEdges);
return graph;
}
double scn::GetVulnerability(UGraph::pGraph graph,size_t indexOfNode)
{
double original_efficiency = GetGlobalEfficiency(graph);
std::pair<IndexList, IndexList> result;
if(indexOfNode != Graph::NaF)
{//compute the vulnerability of one node
//remove the current node, note: only in_degree is used in
//UGraph
result = graph->RemoveNode(indexOfNode);
IndexList& edges = result.first;
//node edge
double new_efficiency = GetGlobalEfficiency(graph);
//restore the original graph
graph->AddEdge(graph->AddNode(indexOfNode), edges);
return (original_efficiency - new_efficiency) / original_efficiency;
}
else
{//compute the vunlerability of the whole network
IndexList setOfNode = graph->CopyIndexOfNodes();
//compute
double max_vul = -1e200, new_vul;
for(auto node = setOfNode.begin(); node != setOfNode.end(); node++)
{
//remove the current node, note: only in_degree is used in
//UGraph
result = graph->RemoveNode(*node);
IndexList& edges = result.first;
new_vul = (original_efficiency - GetGlobalEfficiency(graph)) / original_efficiency;
if(new_vul > max_vul)
max_vul = new_vul;
//restore the original graph
graph->AddEdge(graph->AddNode(*node), edges);
}
return max_vul;
}
}