void Compute(graph<vertex>& GA, commandLine P) {
t1.start();
long start = P.getOptionLongValue("-r",0);
if(GA.V[start].getOutDegree() == 0) {
cout << "starting vertex has degree 0" << endl;
return;
}
const uintE K = P.getOptionIntValue("-K",10);
const uintE N = P.getOptionIntValue("-N",10);
const double t = P.getOptionDoubleValue("-t",3);
srand (time(NULL));
uintE seed = rand();
const intE n = GA.n;
//walk length probabilities
double* fact = newA(double,K);
fact[0] = 1;
for(long k=1;k<K;k++) fact[k] = k*fact[k-1];
double* probs = newA(double,K);
for(long k=0;k<K;k++) probs[k] = exp(-t)*pow(t,k)/fact[k];
unordered_map<uintE,double> p;
for(long i=0;i<N;i++) {
double randDouble = (double) hashInt(seed++) / UINT_E_MAX;
long j = 0;
double mass = 0;
uintE x = start;
do {
mass += probs[j];
if(randDouble < mass) break;
x = walk(x,GA.V,seed++);
j++;
} while(j <= K);
p[x]++;
}
for(auto it=p.begin();it!=p.end();it++) {
p[it->first] /= N;
}
free(probs); free(fact);
t1.stop();
pairIF* A = newA(pairIF,p.size());
long numNonzerosQ = 0;
for(auto it = p.begin(); it != p.end(); it++) {
A[numNonzerosQ++] = make_pair(it->first,it->second);
}
sweepObject sweep = sweepCut(GA,A,numNonzerosQ,start);
free(A);
cout << "number of vertices touched = " << p.size() << endl;
cout << "number of edges touched = " << sweep.vol << endl;
cout << "conductance = " << sweep.conductance << " |S| = " << sweep.sizeS << " vol(S) = " << sweep.volS << " edgesCrossing = " << sweep.edgesCrossing << endl;
t1.reportTotal("computation time");
}
void Compute(graph<vertex>& GA, commandLine P) {
t1.start();
long start = P.getOptionLongValue("-r",0);
if(GA.V[start].getOutDegree() == 0) {
cout << "starting vertex has degree 0" << endl;
return;
}
const int procs = P.getOptionIntValue("-p",0);
if(procs > 0) setWorkers(procs);
const double t = P.getOptionDoubleValue("-t",3);
const double epsilon = P.getOptionDoubleValue("-e",0.000000001);
const uintE N = P.getOptionIntValue("-N",1);
const intE n = GA.n;
const double constant = exp(t)*epsilon/(2*(double)N);
double* psis = newA(double,N);
double* fact = newA(double,N);
fact[0] = 1;
for(long k=1;k<N;k++) fact[k] = k*fact[k-1];
double* tm = newA(double,N);
{parallel_for(long m=0;m<N;m++) tm[m] = pow(t,m);}
{parallel_for(long k=0;k<N;k++) {
psis[k] = 0;
for(long m=0;m<N-k;m++)
psis[k] += fact[k]*tm[m]/(double)fact[m+k];
}}
sparseAdditiveSet<float> x = sparseAdditiveSet<float>(10000,1,0.0);
sparseAdditiveSet<float> r = sparseAdditiveSet<float>(2,1,0.0);
x.insert(make_pair(start,0.0));
r.insert(make_pair(start,1.0));
vertexSubset Frontier(n,start);
long j = 0, totalPushes = 0;
while(Frontier.numNonzeros() > 0){
totalPushes += Frontier.numNonzeros();
uintT* Degrees = newA(uintT,Frontier.numNonzeros());
{parallel_for(long i=0;i<Frontier.numNonzeros();i++) Degrees[i] = GA.V[Frontier.s[i]].getOutDegree();}
long totalDegree = sequence::plusReduce(Degrees,Frontier.numNonzeros());
free(Degrees);
if(j+1 < N) {
long rCount = r.count();
//make bigger hash table initialized to 0.0's
sparseAdditiveSet<float> new_r = sparseAdditiveSet<float>(max(100L,min((long)n,totalDegree+rCount)),LOAD_FACTOR,0.0);
vertexMap(Frontier,Local_Update(x,r));
vertexSubset output = edgeMap(GA, Frontier, HK_F<vertex>(x,r,new_r,GA.V,t/(double)(j+1)));
r.del();
r = new_r;
if(x.m < ((uintT) 1 << log2RoundUp((uintT)(LOAD_FACTOR*min((long)n,rCount+output.numNonzeros()))))) {
sparseAdditiveSet<float> new_x = sparseAdditiveSet<float>(LOAD_FACTOR*min((long)n,rCount+output.numNonzeros()),LOAD_FACTOR,0.0); //make bigger hash table
new_x.copy(x);
x.del();
x = new_x;
}
output.del();
//compute active set (faster in practice to just scan over r)
_seq<ACLpair> vals = r.entries(activeF<vertex>(GA.V,constant/psis[j+1]));
uintE* Active = newA(uintE,vals.n);
parallel_for(long i=0;i<vals.n;i++) Active[i] = vals.A[i].first;
Frontier.del(); vals.del();
Frontier = vertexSubset(n,vals.n,Active);
j++;
} else { //last iteration