size_t scn::MRTofRandomWalk(UGraph::pGraph graph)
{
size_t total_steps = 0;
vector<size_t> neighbors;
srand(size_t(time(00)));
//#pragma omp parallel for shared(total_steps) private(neighbors)
for(size_t source = 0; source < graph->GetNumberOfNodes(); source++)
{
// if(omp_get_thread_num() == 0)
// cout<<"Random walk on "<<source<<"/"<<graph->GetNumberOfNodes() / omp_get_num_procs()<<endl;
size_t next = source;
size_t steps = 0;
do
{
neighbors.assign(graph->find(next)->begin(), graph->find(next)->end());
next = neighbors[rand() % neighbors.size()];
steps++;
}while(next != source);
//#pragma omp critical
{
total_steps += steps;
}
}
return static_cast<double>(total_steps) /
static_cast<double>(graph->GetNumberOfNodes());
}
void scn::RunSPFA(UGraph::pGraph graph,size_t indexOfSource, std::unordered_map<size_t,size_t> &distance)
{
assert(graph->HasNode(indexOfSource));
// Map<size_t>& distance = distance_sssp;
//distance, stored the distance information of each node
//init
for(auto node = graph->begin(); node != graph->end(); node++)
{
distance[*node] = Graph::NaF;
}
distance[indexOfSource] = 0;
queue<size_t> queue_buffer;
unordered_set<size_t> in_queue;
queue_buffer.push(indexOfSource);//push source node
size_t front;
while(!queue_buffer.empty())
{
front = queue_buffer.front();
queue_buffer.pop();
in_queue.erase(front);
auto node = graph->find(front);
for(auto other = node->begin(); other != node->end(); other++)
{
if(in_queue.find(*other) == in_queue.end() &&
distance[front] + 1 < distance[*other])
{
distance[*other] = distance[front] + 1;
queue_buffer.push(*other);
in_queue.insert(*other);
}
}
}
}
size_t scn::RandomWalkBySARW(UGraph::pGraph graph,size_t indexOfSource, size_t indexOfTarget)
{
unordered_set<size_t> neighbors_of_target(graph->find(indexOfTarget)->begin(),
graph->find(indexOfTarget)->end());
vector<size_t> neighbors;
size_t steps = 0;
size_t next = indexOfSource;
unordered_set<size_t> history;
stack<size_t> precessors;
history.insert(indexOfSource);
precessors.push(indexOfSource);
srand(size_t(time(00)));
// judge first
if(graph->HasEdge(indexOfSource, indexOfTarget))
return 1;
do
{
auto other = graph->find(next);
neighbors.clear();
for(auto iter = other->begin(); iter != other->end(); iter++)
{
if(history.find(*iter) == history.end())
neighbors.push_back(*iter);
}
if(neighbors.empty())
{
history.insert(*other);
precessors.pop();
next = precessors.top();
history.insert(next);
steps++;
continue;
}
do
{
next = neighbors[rand() % neighbors.size()];
}while(history.find(next) != history.end());
steps++;
history.insert(next);
precessors.push(next);
}while(neighbors_of_target.find(next) == neighbors_of_target.end());
return steps;
}
size_t scn::RandomWalkByURW(UGraph::pGraph graph,size_t indexOfSource, size_t indexOfTarget)
{
unordered_set<size_t> neighbors_of_target(graph->find(indexOfTarget)->begin(),
graph->find(indexOfTarget)->end());
vector<size_t> neighbors;
size_t steps = 0;
size_t next = indexOfSource;
srand(size_t(time(00)));
do
{
neighbors.assign(graph->find(next)->begin(), graph->find(next)->end());
next = neighbors[rand() % neighbors.size()];
steps++;
}while(neighbors_of_target.find(next) == neighbors_of_target.end());
return steps;
}
void scn::RunDjikstra(UGraph::pGraph graph,size_t indexOfSource,std::unordered_map<size_t,size_t> &distance)
{
//auto& distance = distance_sssp;//using distance_sssp eariler
assert(graph->HasNode(indexOfSource));
//init
//distance.reserve(graph->GetNumberOfNodes());
for(auto node = graph->begin(); node != graph->end(); node++)
{
distance[*node] = Graph::NaF;
}
distance[indexOfSource] = 0;
list<size_t> queue;
//fill index of nodes into queue
for(size_t i = 0; i < graph->GetNumberOfNodes(); i++)
{
queue.push_back(i);
}
//begin
size_t next_distance;
while(!queue.empty())
{
//get min one
auto min = min_element(queue.begin(), queue.end(),
[&](const size_t &one, const size_t &two)->bool
{
if(distance[one] < distance[two])
return true;
else
return false;
});
auto node = graph->find(*min);
if(distance[*node] < Graph::NaF)
next_distance = distance[*node] + 1;
else
next_distance = Graph::NaF;
//relax neighbors
for(auto other = node->begin(); other != node->end(); other++)
{
if(distance[*other] > next_distance)
{
distance[*other] = next_distance;
}
}
queue.erase(min);
}
}
double scn::GetClusteringCoeff(UGraph::pGraph graph,size_t indexOfNode)
{
if(indexOfNode == UGraph::NaF)
{//the whole network
double coefficient = 0;
for(auto node = graph->begin(); node != graph->end(); node++)
{
size_t numberOfTriangles = 0;
for(auto other1 = node->begin(); other1 != node->end(); other1++)
{
for(auto other2 = other1 + 1; other2 != node->end(); other2++)
{
if(graph->HasEdge(*other1, *other2))
numberOfTriangles++;
}
}
if(node->GetDegree()>1)
{
coefficient += 2 * static_cast<double>(numberOfTriangles) /
(node->GetDegree() * (node->GetDegree() - 1));
}
}
return coefficient / graph->GetNumberOfNodes();
}
else
{//one vertex
auto node = graph->find(indexOfNode);
double numberOfTriangles = 0;
for(auto other1 = node->begin(); other1 != node->end(); other1++)
{
for(auto other2 = other1 + 1; other2 != node->end(); other2++)
{
if(graph->HasEdge(*other1, *other2))
numberOfTriangles++;
}
}
if(node->GetDegree()>1)
return 2 * numberOfTriangles / (node->GetDegree() * (node->GetDegree() - 1));
else
return 0.0;
}
}
IndexList scn::FindClosureGroup(UGraph::pGraph graph,size_t indexOfSeed, size_t length)
{
unordered_set<size_t> list;
list.insert(indexOfSeed);
//breadth-first search to find adjacent nodes
queue<size_t> search_queue;
unordered_set<size_t> in_queue;
//init
search_queue.push(indexOfSeed);
in_queue.insert(indexOfSeed);
//begin
size_t front;
while(!search_queue.empty())
{
front = search_queue.front();
search_queue.pop();
in_queue.erase(front);
auto node = graph->find(front);
for(auto other = node->begin(); other != node->end(); other++)
{
if(in_queue.find(*other) != in_queue.end())
continue;
if(list.find(*other) != list.end())
continue;
if(all_of(list.begin(), list.end(), [&](size_t i)->bool
{
if(GetShortestDistance(graph,i, *other) < length)
return true;
else
return false;
}))
{
search_queue.push(*other);
in_queue.insert(*other);
list.insert(*other);
}
}
}
return IndexList(list.begin(), list.end());
}
size_t scn::GetShortestDistance(UGraph::pGraph graph,size_t indexOfSource, size_t indexOfTarget)
{
assert(graph->HasNode(indexOfSource) && graph->HasNode(indexOfTarget));
//breadth-first search
queue<size_t> search_queue;
std::unordered_map<size_t,size_t> distance;
unordered_set<size_t> in_queue;
size_t front;
//initial
distance[indexOfSource] = 0;
search_queue.push(indexOfSource);
in_queue.insert(indexOfSource);
while(!search_queue.empty())
{
front = search_queue.front();
search_queue.pop();
in_queue.erase(front);
auto node = graph->find(front);
for(auto other = node->begin(); other != node->end(); other++)
{
if(*other == indexOfTarget)
return distance[*node] + 1;
if(in_queue.find(*other) == in_queue.end() &&
(distance.find(*other) == distance.end() || distance[front] + 1 < distance[*other]))
{
distance[*other] = distance[front] + 1;
search_queue.push(*other);
in_queue.insert(*other);
}
}
}
//if this point is reached, the indexOfTarget is an isolated node
return Graph::NaF;
}
pair<size_t, size_t> scn::GetNumberOfShortestPath(UGraph::pGraph graph,size_t indexOfSource, size_t indexOfTarget,
size_t indexOfThrough)
{
assert(graph->HasNode(indexOfSource));
assert(graph->HasNode(indexOfTarget));
//find shortest path
std::unordered_map<size_t,size_t> distance;
//auto& distance = distance_sssp;
RunSPFA(graph,indexOfSource,distance);
if(indexOfThrough == UGraph::NaF)
{//no passing through any specified node
size_t sum = 0;
queue<size_t> path;
path.push(indexOfTarget);
//breadth-first search
while(!path.empty())
{
if(indexOfSource == path.front())
sum++;
else
{
auto current = graph->find(path.front());
size_t current_distance = distance[*current];
for(auto other = current->begin(); other != current->end(); other++)
{
if(distance[*other] == current_distance - 1)
path.push(*other);
}
}
path.pop();
}
return make_pair(sum, sum);
}
else
{
assert(graph->HasNode(indexOfThrough));
assert(indexOfSource != indexOfThrough);
assert(indexOfTarget != indexOfThrough);
size_t sum_all = 0;
size_t sum_through = 0;
queue<pair<size_t, bool>> path;//pair(indexOfNode, Does it Pass
//through the give node?
path.push(make_pair(indexOfTarget, false));
//breadth-first search
while(!path.empty())
{
auto current = path.front();
if(current.first == indexOfThrough)
current.second = true;
if(indexOfSource == current.first)
{
sum_all++;
if(current.second)
sum_through++;
}
else
{
size_t current_distance = distance[current.first];
auto current_node = graph->find(current.first);
for(auto other = current_node->begin(); other != current_node->end(); other++)
{
if(distance[*other] == current_distance - 1)
path.push(make_pair(*other, current.second));
}
}
path.pop();
}
return make_pair(sum_all, sum_through);
}
}
