public double onePageRankIteration(CategoryGraph graph) {
double nextRanks[] = new double[graph.catCosts.length];
Arrays.fill(nextRanks, (1.0 - DAMPING_FACTOR) / graph.catCosts.length);
for (int i = 0; i < graph.catParents.length; i++) {
int d = graph.catParents[i].length; // degree
double pr = graph.catCosts[i]; // current page-rank
for (int j : graph.catParents[i]) {
nextRanks[j] += DAMPING_FACTOR * pr / d;
}
}
double diff = 0.0;
for (int i = 0; i < graph.catParents.length; i++) {
diff += Math.abs(graph.catCosts[i] - nextRanks[i]);
}
graph.catCosts = nextRanks;
return diff;
}
private void buildGraph(CategoryGraph graph) throws DaoException {
LOG.info("building category graph");
graph.catPages = new int[graph.catIndexes.size()][];
graph.catParents = new int[graph.catIndexes.size()][];
graph.catChildren = new int[graph.catIndexes.size()][];
graph.catCosts = new double[graph.catIndexes.size()];
Arrays.fill(graph.catPages, new int[0]);
Arrays.fill(graph.catParents, new int[0]);
Arrays.fill(graph.catChildren, new int[0]);
// count reverse edges
int totalEdges = 0;
int numCatChildren[] = new int[graph.catIndexes.size()];
int numCatParents[] = new int[graph.catIndexes.size()];
int numCatPages[] = new int[graph.catIndexes.size()];
DaoFilter filter = new DaoFilter().setLanguages(graph.language);
for (LocalCategoryMember lcm : catDao.get(filter)) {
int catIndex1 =
graph.getCategoryIndex(lcm.getArticleId()); // cat index for page (probably -1)
int catIndex2 = graph.getCategoryIndex(lcm.getCategoryId()); // cat index for cat
if (catIndex1 >= 0 && catIndex2 >= 0) {
numCatChildren[catIndex2]++;
numCatParents[catIndex1]++;
} else if (catIndex2 >= 0) {
numCatPages[catIndex2]++;
}
totalEdges++;
}
// allocate space
for (int i = 0; i < graph.catIndexes.size(); i++) {
graph.catPages[i] = new int[numCatPages[i]];
graph.catChildren[i] = new int[numCatChildren[i]];
graph.catParents[i] = new int[numCatParents[i]];
}
// fill it
for (LocalCategoryMember lcm : catDao.get(filter)) {
int catIndex1 =
graph.getCategoryIndex(lcm.getArticleId()); // cat index for page (probably -1)
int catIndex2 = graph.getCategoryIndex(lcm.getCategoryId()); // cat index for cat
if (catIndex1 >= 0 && catIndex2 >= 0) {
graph.catChildren[catIndex2][--numCatChildren[catIndex2]] = catIndex1;
graph.catParents[catIndex1][--numCatParents[catIndex1]] = catIndex2;
} else if (catIndex2 >= 0) {
graph.catPages[catIndex2][--numCatPages[catIndex2]] = lcm.getArticleId();
}
}
for (int n : numCatChildren) {
assert (n == 0);
}
for (int n : numCatPages) {
assert (n == 0);
}
for (int n : numCatParents) {
assert (n == 0);
}
LOG.info("loaded " + totalEdges + " edges in category graph");
}