Add graph references

2026-06-28 13:49:01 +01:00
parent 0a9807e448
commit a11edf0c53
2578 changed files with 868045 additions and 0 deletions
@@ -0,0 +1,104 @@
+/* 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;
+}