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Abdelrahman Said a11edf0c53 Add graph references
2026-06-28 13:49:01 +01:00

105 lines
4.1 KiB
C

/* igraph library.
Copyright (C) 2021 The igraph development team <igraph@igraph.org>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include <igraph.h>
#include "test_utilities.h"
void call_and_print(igraph_t *graph, igraph_vs_t vids, igraph_vector_t *weights) {
igraph_vector_t result;
igraph_vector_init(&result, 0);
IGRAPH_ASSERT(igraph_constraint(graph, &result, vids, weights) == IGRAPH_SUCCESS);
print_vector(&result);
igraph_vector_destroy(&result);
printf("\n");
}
int main(void) {
igraph_t g_0, g_1, g_4_full, g_4_full_split, g_4_full_loop, g_4_line, g_hole;
igraph_vector_t weights_full, weights_full_split, weights_line, result;
igraph_vector_init_real(&weights_line, 6, 1., 0., 0., 1., 0., 1.);
igraph_vector_init_real(&weights_full, 6, 1., 1., 1., 1., 1., 1.);
igraph_vector_init_real(&weights_full_split, 9, .5, .5, 1., 1., 1., 1./3., 1./3., 1./3., 1.);
igraph_vector_init(&result, 0);
igraph_small(&g_0, 0, 0, -1);
igraph_small(&g_1, 1, 0, -1);
igraph_small(&g_4_full, 4, IGRAPH_UNDIRECTED, 0,1, 0,2, 0,3, 1,2, 1,3, 2,3, -1);
igraph_small(&g_4_full_loop, 4, IGRAPH_UNDIRECTED, 0,0, 0,1, 0,2, 0,3, 1,2, 1,3, 2,3, -1);
igraph_small(&g_4_full_split, 4, IGRAPH_UNDIRECTED, 0,1, 0,1, 0,2, 0,3, 1,2,
1,3, 1,3, 1,3, 2,3, -1);
igraph_small(&g_4_line, 4, IGRAPH_UNDIRECTED, 0,1, 1,2, 2,3, -1);
igraph_small(&g_hole, 9, IGRAPH_UNDIRECTED, 0,1, 0,2, 0,3, 1,2, 1,3, 2,3, 3,4, 4,5,
5,6, 5,7, 5,8, 6,7, 6,8, 7,8, -1);
printf("No vertices:\n");
call_and_print(&g_0, igraph_vss_none(), NULL);
printf("One vertex:\n");
call_and_print(&g_1, igraph_vss_1(0), NULL);
printf("Line graph, 4 vertices:\n");
call_and_print(&g_4_line, igraph_vss_all(), NULL);
printf("Full graph, 4 vertices, weights make it a line:\n");
call_and_print(&g_4_full, igraph_vss_all(), &weights_line);
/*
each p_ij and p_ji is equal to 1/3, because each node has 3 connections with
equal weight and p_ij is z_ij/sum_j(z_ij) where z are the edge weights.
so C_ij = (1/3 + (1/3)^2) for each j, which means C_i = (1/3 + 2/9)^2 *3
= 0.925925925925926
*/
printf("Full graph, 4 vertices, all same weights:\n");
call_and_print(&g_4_full, igraph_vss_all(), &weights_full);
printf("Full graph, 4 vertices, all same weights, but split over multiple edges:\n");
call_and_print(&g_4_full_split, igraph_vss_all(), &weights_full_split);
printf("Full graph, 4 vertices, no weights:\n");
call_and_print(&g_4_full, igraph_vss_all(), NULL);
printf("Full graph, 4 vertices, no weights, with loop:\n");
call_and_print(&g_4_full_loop, igraph_vss_all(), NULL);
/*
for node 0, each p_ij is again equal to 1/3, but p_ji equals 1/4 for j = 3,
because that's connected to 4 other nodes, so for example for C_01 the contribution
is
C_01 = (p_01 + p_02p_21 + p_03p_31)^2 = (1/3 + 1/9 + 1/12)^2
and you end up with:
((1/3 + 2/9)^2 ) + ((1/3 + 1/9 + 1/12)^2 * 2) = 0.8657407407407408
*/
printf("Hole in middle of two clusters:\n");
call_and_print(&g_hole, igraph_vss_all(), NULL);
igraph_destroy(&g_0);
igraph_destroy(&g_1);
igraph_destroy(&g_4_full);
igraph_destroy(&g_4_full_loop);
igraph_destroy(&g_4_full_split);
igraph_destroy(&g_4_line);
igraph_destroy(&g_hole);
igraph_vector_destroy(&weights_line);
igraph_vector_destroy(&weights_full);
igraph_vector_destroy(&weights_full_split);
igraph_vector_destroy(&result);
VERIFY_FINALLY_STACK();
return 0;
}