ne_mut_lib.c

/*===========================================================================
 NetEvo Foundation Library
 Copyright (C) 2009, 2010 Thomas E. Gorochowski <tgorochowski@me.com>
 Bristol Centre for Complexity Sciences, University of Bristol, Bristol, UK
 ---------------------------------------------------------------------------- 
 NetEvo is a computing framework designed to allow researchers to investigate 
 evolutionary aspects of dynamical complex networks. By providing tools to 
 easily integrate each of these factors in a coherent way, it is hoped a 
 greater understanding can be gained of key attributes and features displayed 
 by complex systems.
 
 NetEvo is open-source software released under the Open Source Initiative 
 (OSI) approved Non-Profit Open Software License ("Non-Profit OSL") 3.0. 
 Detailed information about this licence can be found in the COPYING file 
 included as part of the source distribution.
 
 This library 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.
 ============================================================================*/


#include "ne_mut_lib.h"
#include "ne_evo.h"
#include <igraph.h>
#include <gsl/gsl_rng.h>
#include <gsl/gsl_randist.h>
#include <string.h>

/* Global random number generator */
extern gsl_rng* neRng;


ne_mut_t * ne_mut_rewire_alloc (ne_real_t expMean)
{  
   ne_mut_t  *mut;
   ne_real_t *params;
   
   if ((mut = (ne_mut_t *)malloc(sizeof(ne_mut_t))) == NULL) {
      ne_error("ne_mut_rewire_alloc: Could not allocate memory for ne_mut.");
      return NULL;
   }
   
   /* Allocate and set parameters */
   if ((params = (ne_real_t *)malloc(sizeof(ne_real_t))) == NULL) {
      ne_error("ne_mut_rewire_alloc: Could not allocate memory for ne_mut.params.");
      free(mut);
      return NULL;
   }
   params[0] = expMean;
   
   /* Set fields */
   mut->type   = NE_MUT_TOP;
   mut->params = params;
   mut->fn     = &ne_mut_rewire;
   
   return mut;
}


ne_err_code_t ne_mut_rewire (ne_sys_t *sys, ne_real_t *params, char *strMut)
{
   int i, nNum, v1Add, v2Add, eNum, eDel, rewirings = 0;
   igraph_es_t esDel;
   char strBuffer[100];
   
   /* Count number of nodes and edges */
   nNum = (int)ne_sys_nodes(sys);
   eNum = (int)ne_sys_edges(sys);
   
   /* Select number of rewirings to perform (exp dist) */
   rewirings = (int)gsl_ran_exponential(neRng, params[0]);
   
   /* Ensure that at least a single rewiring is performed */
   if ( rewirings <= 0 ) 
      rewirings = 1;
   
   /* Perform the chosen number of rewirings */
   for (i=0; i<rewirings; i++) {
      
      /* Pick an existing edge to remove */
      eDel = (int)(gsl_rng_get(neRng)%eNum);
      esDel = igraph_ess_1((igraph_integer_t)eDel);

      /* Pick two valid nodes to add a new edge between */
      do {
         v1Add = (int)(gsl_rng_get(neRng)%nNum);
         do {
            v2Add = (int)(gsl_rng_get(neRng)%nNum);
         } while ( v1Add == v2Add );
      } while ( ne_sys_edge_exists(sys, v1Add, v2Add) == TRUE );
      
      /* Rewire network */
      igraph_delete_edges(sys->graph, esDel);
      ne_evo_del_edge(strBuffer, (int)IGRAPH_FROM(sys->graph, eDel), (int)IGRAPH_TO(sys->graph, eDel));
      strcat(strMut, strBuffer);
      igraph_add_edge(sys->graph, v1Add, v2Add);
      ne_evo_add_edge(strBuffer, v1Add, v2Add, 0);
      strcat(strMut, strBuffer);
   }
   
   return NE_SUCCESS;
}