int
run_page_rank (FILE *f, int argc, char **argv)
{
char line[128];
PageRank *pr = page_rank_new ();
int seed;
double *r;
seed = page_rank_find_node (pr, "-");
page_rank_add_edge (pr, "-", "rillian");
for (;;)
{
char *from;
char *to;
char *color;
if (fgets (line, sizeof(line), f) == NULL)
break;
if (get_graph_line (line, &from, &to, &color))
page_rank_add_edge (pr, from, to);
}
r = page_rank_compute (pr, seed, 0.15);
#if 0
print_page_rank (pr, r);
#endif
g_free (r);
return 0;
}
PageRankScorerError
page_rank_scorer_new(PageRankScorer **prs, PageDB *db) {
PageRankScorer *p = *prs = malloc(sizeof(*p));
if (!p)
return page_rank_scorer_error_memory;
p->error = error_new();
if (p->error == 0) {
free(p);
return page_rank_scorer_error_memory;
}
p->page_db = db;
if (page_rank_new(&p->page_rank, db->path, 1000) != 0) {
page_rank_scorer_set_error(p, page_rank_scorer_error_internal, __func__);
page_rank_scorer_add_error(p, "initializing PageRank");
page_rank_scorer_add_error(p, p? p->error->message: "NULL");
return p->error->code;
}
page_rank_scorer_set_persist(p, PAGE_RANK_SCORER_PERSIST);
page_rank_scorer_set_use_content_scores(p, PAGE_RANK_SCORER_USE_CONTENT_SCORES);
return 0;
}
/* Checks the accuracy of the PageRank computation */
void
test_page_rank(CuTest *tc) {
printf("%s\n", __func__);
/* Compute the PageRank score of the following graph
* +-->2---+
* | | |
* | v v
* 1-->5<--3
* ^ ^ |
* | | |
* +---4<--+
*
* The link matrix L[i,j], where L[i,j] = 1 means 'i' links to 'j' is:
*
* +- -+
* | 0 1 0 0 1 |
* | 0 0 1 0 1 |
* L = | 0 0 0 1 1 |
* | 1 0 0 0 1 |
* | 0 0 0 0 0 |
* +- -+
*
* Since page "5" has no outbound links, it is assumed it links to every other page:
*
* +- -+
* | 0 1 0 0 1 |
* | 0 0 1 0 1 |
* L = | 0 0 0 1 1 |
* | 1 0 0 0 1 |
* | 1 1 1 1 1 |
* +- -+
*
* The out degree is:
*
* deg = {2, 2, 2, 2, 5}
*
* Dividing each row with the out degree and transposing we get the matrix:
*
* M[i, j] = L[j, i]/deg[j]
*
* we get:
*
* +- -+
* | 0 0 0 0.5 0.2 |
* | 0.5 0 0 0 0.2 |
* M = | 0 0.5 0 0 0.2 |
* | 0 0 0.5 0 0.2 |
* | 0.5 0.5 0.5 0.5 0.2 |
* +- -+
*
* If 'd' is the damping then the PageRank 'PR' is:
*
* 1 - d
* PR = ----- + (d * M)*PR
* N
*
* For d=0.85 the numerical solution is:
*
* PR(1) = PR(2) = PR(3) = PR(4) = 0.15936255
* PR(5) = 0.3625498
*/
char test_dir[] = "test-pagedb-XXXXXX";
mkdtemp(test_dir);
PageDB *db;
int ret = page_db_new(&db, test_dir);
CuAssert(tc,
db!=0? db->error->message: "NULL",
ret == 0);
db->persist = 0;
char *urls[5] = {"1", "2", "3", "4", "5" };
LinkInfo links_1[] = {{"2", 0.1}, {"5", 0.1}};
LinkInfo links_2[] = {{"3", 0.1}, {"5", 0.1}};
LinkInfo links_3[] = {{"4", 0.1}, {"5", 0.1}};
LinkInfo links_4[] = {{"1", 0.1}, {"5", 0.1}};
LinkInfo *links[5] = {
links_1, links_2, links_3, links_4, 0
};
int n_links[5] = {2, 2, 2, 2, 0};
for (int i=0; i<5; ++i) {
CrawledPage *cp = crawled_page_new(urls[i]);
for (int j=0; j<n_links[i]; ++j)
crawled_page_add_link(cp, links[i][j].url, links[i][j].score);
cp->score = i/5.0;
crawled_page_set_hash64(cp, i);
PageInfoList *pil;
CuAssert(tc,
db->error->message,
page_db_add(db, cp, &pil) == 0);
page_info_list_delete(pil);
crawled_page_delete(cp);
}
// Without content scores
// ------------------------------------------------------------------------
PageDBLinkStream *st;
CuAssert(tc,
db->error->message,
page_db_link_stream_new(&st, db) == 0);
st->only_diff_domain = 0;
PageRank *pr;
ret = page_rank_new(&pr, test_dir, 5);
CuAssert(tc,
pr!=0? pr->error->message: "NULL",
ret == 0);
pr->precision = 1e-6;
CuAssert(tc,
pr->error->message,
page_rank_compute(pr,
st,
page_db_link_stream_next,
page_db_link_stream_reset) == 0);
page_db_link_stream_delete(st);
uint64_t idx;
float *score;
float scores[5] = {0.15936255, 0.15936255, 0.15936255, 0.15936255, 0.3625498};
for (int i=0; i<5; ++i) {
CuAssert(tc,
db->error->message,
page_db_get_idx(db, page_db_hash(urls[i]), &idx) == 0);
CuAssertPtrNotNull(tc,
score = mmap_array_idx(pr->value1, idx));
CuAssertDblEquals(tc, scores[i], *score, 1e-6);
}
CHECK_DELETE(tc, pr->error->message, page_rank_delete(pr));
// With content scores, damping = 0
// ------------------------------------------------------------------------
CuAssert(tc,
db->error->message,
page_db_link_stream_new(&st, db) == 0);
st->only_diff_domain = 0;
ret = page_rank_new(&pr, test_dir, 5);
CuAssert(tc,
pr!=0? pr->error->message: "NULL",
ret == 0);
pr->precision = 1e-6;
pr->damping = 0.0;
CuAssert(tc,
db->error->message,
page_db_get_scores(db, &pr->scores) == 0);
CuAssert(tc,
pr->error->message,
page_rank_compute(pr,
st,
page_db_link_stream_next,
page_db_link_stream_reset) == 0);
page_db_link_stream_delete(st);
float total_score = 0.0;
for (int i=0; i<5; ++i)
total_score += scores[i] = *((float*)mmap_array_idx(pr->scores, i));
for (int i=0; i<5; ++i) {
CuAssert(tc,
db->error->message,
page_db_get_idx(db, page_db_hash(urls[i]), &idx) == 0);
CuAssertPtrNotNull(tc,
score = mmap_array_idx(pr->value1, idx));
CuAssertDblEquals(tc, scores[idx]/total_score, *score, 1e-6);
}
CHECK_DELETE(tc, pr->scores->error->message, mmap_array_delete(pr->scores));
CHECK_DELETE(tc, pr->error->message, page_rank_delete(pr));
// With content scores, damping = 0.5
// ------------------------------------------------------------------------
CuAssert(tc,
db->error->message,
page_db_link_stream_new(&st, db) == 0);
st->only_diff_domain = 0;
ret = page_rank_new(&pr, test_dir, 5);
CuAssert(tc,
pr!=0? pr->error->message: "NULL",
ret == 0);
pr->precision = 1e-6;
pr->damping = 0.5;
CuAssert(tc,
db->error->message,
page_db_get_scores(db, &pr->scores) == 0);
CuAssert(tc,
pr->error->message,
page_rank_compute(pr,
st,
page_db_link_stream_next,
page_db_link_stream_reset) == 0);
page_db_link_stream_delete(st);
float expected_pr[] = {
0.06386554621848739,
0.08739495798319329,
0.1647058823529412,
0.25546218487394956,
0.4285714285714286
};
for (int i=0; i<5; ++i) {
CuAssert(tc,
db->error->message,
page_db_get_idx(db, page_db_hash(urls[i]), &idx) == 0);
CuAssertPtrNotNull(tc,
score = mmap_array_idx(pr->value1, idx));
CuAssertDblEquals(tc, expected_pr[i], *score, 1e-6);
}
CHECK_DELETE(tc, pr->scores->error->message, mmap_array_delete(pr->scores));
CHECK_DELETE(tc, pr->error->message, page_rank_delete(pr));
page_db_delete(db);
}