void pageRank(Graph g, float* solution, float damping, float convergence)
{
int numNodes = num_nodes(g);
State<float> s(g, damping, convergence);
VertexSet* frontier = newVertexSet(SPARSE, numNodes, numNodes);
for (int i = 0; i < numNodes; i++) {
addVertex(frontier, i);
}
float error = INFINITY;
while (error > convergence) {
Local<float> local(g, s.pcurr, s.pnext, s.diff, damping);
VertexSet* frontier2 = edgeMap<State<float> >(g, frontier, s);
VertexSet* frontier3 = vertexMap<Local<float> >(frontier2, local);
freeVertexSet(frontier);
freeVertexSet(frontier2);
frontier = frontier3;
error = s.getError();
std::swap(s.pcurr, s.pnext);
}
freeVertexSet(frontier);
#pragma omp parallel for schedule(static)
for (int i = 0; i < numNodes; i++) {
solution[i] = s.pcurr[i];
}
}
void decompose(graph *g, int *decomp, int* dus, int maxVal, int maxId) {
int* cluster;
int* nextcluster;
int iter = 0;
int total_num = g -> num_nodes;
cluster = (int*) malloc(sizeof(int*) * total_num);
nextcluster = (int*) malloc(sizeof(int*) * total_num);
memset(cluster, NA, sizeof(int) * total_num);
memset(nextcluster, NA, sizeof(int) * total_num);
// int* dus = getDus(total_num, decomp, &maxVal, &maxId); // rate = 1/beta beta哪里来
VertexSet* frontier = newVertexSet(SPARSE, 1, total_num);
addVertex(frontier, maxId);
VertexSet *newFrontier;
int max_dus = 0;
for (int i = 0; i < total_num; i++) {
max_dus = max_dus >= dus[i] ? max_dus : dus[i];
}
while (frontier->size > 0) {
iter += 1;
Decomosition dec(cluster, nextcluster);
newFrontier = edgeMap(g, frontier, dec, NORETURN);
freeVertexSet(frontier);
frontier = newFrontier;
// start growing all balls i at the next iter with
// // uncluster center i and with maxDu - dus[i] < iter
// foreach vertex i in not_cluster {
// if (iter > du_max - dus[i]) {
// frontier->add(i);
// }
// }
UpdateFrontier uf(max_dus, iter, dus);
vertexMap(frontier, uf, YESRETURN);
ClusterCopy vc(cluster, nextcluster);
vertexMap(frontier, vc, NORETURN);
}
freeVertexSet(frontier);
free(cluster);
free(nextcluster);
}
// Finds the BFS distance to each node starting from node 0.
void bfs(graph *g, int *solution) {
Bfs f(g, solution);
// Initialize frontier.
VertexSet* frontier = newVertexSet(SPARSE, 1, num_nodes(g));
addVertex(frontier, 0);
VertexSet *newFrontier;
while (frontier->size != 0) {
newFrontier = edgeMap<Bfs>(g, frontier, f);
freeVertexSet(frontier);
frontier = newFrontier;
f.currentDistance++;
}
freeVertexSet(frontier);
}
/**
Given a graph, select k random start vertices. Call these
k vertices set S. For all vertices v in the graph, find the farthest
distance between v and any of the vertices in S. Store this is distField.
Note that this implementation is faster than running K separate BFSs in
parallel because all k BFSs share a frontier. This means that for each
node we must store a bit vector of size K bits, indicating whether or not
a node has been visited yet by the kth BFS.
Note that a node v will continue to be added to the frontier as long as its
source vertex u has a different bit vector than it. This means that v is
being visited for the first time by at least one of the K BFSs. Thus we must
also increment our estimate of its radius since the radius is the FARTHEST
distance of node v to any of the u source vertices.
At the end of the algorithm distField will contain the maximum distance from
each node v in the graph to any of the K source nodes. The final radius
estimate of the graph is obtained by taking the max radius obtained from all
nodes in the graph. Note that this is an estimate because we only ran a BFS
from K nodes. If we wanted an exact radius we would have had to run a BFS from
every single node in the graph.
**/
void kBFS(graph *g, int *distField) {
int** visited;
int** nextVisited;
int* radii;
int iter = 0;
// set up globals
#pragma omp parallel for schedule(static)
for (int i = 0; i < g->num_nodes; i++)
distField[i] = NA;
radii = distField;
visited = (int**) malloc(sizeof(int*) * g->num_nodes);
nextVisited = (int**) malloc(sizeof(int*) * g->num_nodes);
for (int i = 0; i < g->num_nodes; i++) {
visited[i] = (int*) malloc(sizeof(int) * NUMWORDS);
nextVisited[i] = (int*) malloc(sizeof(int) * NUMWORDS);
memset(visited[i], 0, sizeof(int) * NUMWORDS);
memset(nextVisited[i], 0, sizeof(int) * NUMWORDS);
}
// initialize the frontier with K random nodes
srand(0);
int numSources = std::min(K, g->num_nodes);
int S[numSources]; // the set of source nodes
for (int i = 0; i < numSources; i++)
S[i] = (std::rand()/(float)RAND_MAX) * g->num_nodes;
VertexSet* frontier = newVertexSet(SPARSE, numSources, g->num_nodes);
for (int i = 0; i < numSources; i++) {
addVertex(frontier, S[i]);
}
// iterate over values 1 thru k to do initialization
VertexSet* ks = newVertexSet(SPARSE, numSources, g->num_nodes);
for (int i = 0; i < numSources; i++)
addVertex(ks, i);
Init i(S, visited, nextVisited, radii);
vertexMap(ks, i, NORETURN);
freeVertexSet(ks);
VertexSet *newFrontier;
while (frontier->size > 0) {
iter = iter + 1;
RadiiUpdate ru(visited, nextVisited, radii, iter);
newFrontier = edgeMap(g, frontier, ru);
freeVertexSet(frontier);
frontier = newFrontier;
VisitedCopy vc(visited, nextVisited);
vertexMap(frontier, vc, NORETURN);
}
for (int i = 0; i < g->num_nodes; i++) {
free(visited[i]);
free(nextVisited[i]);
}
freeVertexSet(frontier);
free(visited);
free(nextVisited);
}
