graphgen.c

/*	##############################################################################################
 *      Advanced RTI System, ARTÌS			http://pads.cs.unibo.it
 *      Large Unstructured NEtwork Simulator (LUNES)
 *
 *      Description:
 *              For a general introduction to LUNES implmentation please see the
 *              file: mig-agents.c
 *
 *              This an external tool used to build graphs that will be used
 *              in the simulator.
 *
 *      Authors:
 *              First version by Gabriele D'Angelo <g.dangelo@unibo.it>
 *
 ###############################################################################################
 #
 #      TODO:
 #
 #              -	Almost everything :-(
 #
 */

#include <igraph/igraph.h>
#include <stdlib.h>

void print_usage() {
    fprintf(stdout, "Syntax error:\n");
    fprintf(stdout, "\tUSAGE: graphgen <#nodes> <#edges> <output_file_name> <max_diameter>\n");
    fprintf(stdout, "\t<#edges> / <#nodes> > 0\n");
    fflush(stdout);
    exit(-1);
}

int main(int argc, char *argv[]) {
    igraph_t         graph;
    igraph_integer_t nodes;
    igraph_integer_t diameter;
    igraph_bool_t    result = (igraph_bool_t)0;
    FILE *           output_dot;
    FILE *           fstatus;
    igraph_integer_t max_diameter;
    igraph_integer_t edges;
    igraph_integer_t edges_per_node;

    if (argc != 5) {
        print_usage();
    }

    nodes        = (igraph_integer_t)atoi(argv[1]);
    edges        = (igraph_integer_t)atof(argv[2]);
    max_diameter = (igraph_integer_t)atoi(argv[4]);

    edges_per_node = (igraph_integer_t)edges / nodes;

    if (nodes == 0 || edges <= nodes - 1 || max_diameter == 0 || edges_per_node == 0) {
        print_usage();
    }

    fprintf(stdout, "Generating a graph with %d vertices and %d edges (~%d edges per node)\n", (int)nodes, (int)edges, (int)edges_per_node);
    fflush(stdout);

    while ((int)(result) != 1) {
        //igraph_erdos_renyi_game(&graph, IGRAPH_ERDOS_RENYI_GNM, nodes, edges, IGRAPH_UNDIRECTED, IGRAPH_NO_LOOPS);
         igraph_watts_strogatz_game(&graph, /*dim=*/ 1, /*size=*/ nodes, /*nei=*/ edges_per_node, /*p=*/ 0.1, /*loops=*/ 0, /*multiple=*/ 0);
        // igraph_k_regular_game(&graph, nodes, edges_per_node, 0, 0);
        igraph_is_connected(&graph, &result, IGRAPH_STRONG);
        igraph_diameter(&graph, &diameter, 0, 0, 0, IGRAPH_UNDIRECTED, 1);
        // if is not connected (result == 0), the diameter constraint is not valid
        if ((int)(result) == 0 && diameter > max_diameter) {
            igraph_destroy(&graph);
        }
    }

    printf("\nConnected graph? (0/1): %d\n", (int)result);
    printf("Diameter of the graph: %d\n", (int)diameter);
    printf("Number of vertices in the graph: %d\n", (int)igraph_vcount(&graph));
    printf("Number of edges in the graph: %d\n", (int)igraph_ecount(&graph));

    output_dot = fopen(argv[3], "w");
    igraph_write_graph_dot(&graph, output_dot);
    fclose(output_dot);

    fstatus = fopen("status.txt", "w");
    fprintf(fstatus, "Diameter of the graph: %d\n", (int)diameter);
    fclose(fstatus);

    igraph_destroy(&graph);
    return(0);
}