From 3aee2fd43e3059a699af2b63c6f2395e5a55e515 Mon Sep 17 00:00:00 2001
From: KatolaZ <katolaz@freaknet.org>
Date: Wed, 27 Sep 2017 15:06:31 +0100
Subject: First commit on github -- NetBunch 1.0

---
 src/conf/conf_model_deg_nocheck.c | 182 ++++++++++++++++++++++++++++++++++++++
 1 file changed, 182 insertions(+)
 create mode 100644 src/conf/conf_model_deg_nocheck.c

(limited to 'src/conf/conf_model_deg_nocheck.c')

diff --git a/src/conf/conf_model_deg_nocheck.c b/src/conf/conf_model_deg_nocheck.c
new file mode 100644
index 0000000..26f89d1
--- /dev/null
+++ b/src/conf/conf_model_deg_nocheck.c
@@ -0,0 +1,182 @@
+/**
+ *  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 3 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
+ *  <http://www.gnu.org/licenses/>.
+ *
+ *  (c) Vincenzo Nicosia 2009-2017 -- <v.nicosia@qmul.ac.uk>
+ * 
+ *  This file is part of NetBunch, a package for complex network
+ *  analysis and modelling. For more information please visit:
+ *
+ *             http://www.complex-networks.net/
+ *
+ *  If you use this software, please add a reference to 
+ *
+ *               V. Latora, V. Nicosia, G. Russo             
+ *   "Complex Networks: Principles, Methods and Applications"
+ *              Cambridge University Press (2017) 
+ *                ISBN: 9781107103184
+ *
+ ***********************************************************************
+ *
+ *  This program samples a multigraph (i.e., a graph that might
+ *  contain self-loops and/or multiple edges) from the configuration
+ *  model, using the degree sequence provided as input.
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include "utils.h"
+#include "iltree.h"
+
+
+
+/* Usage*/
+void usage(char *argv[]){
+  printf("********************************************************************\n"
+         "**                                                                **\n"
+         "**                -*-  conf_model_deg_nocheck  -*-                **\n"
+         "**                                                                **\n"
+         "**  Sample a multigraph from the configuration model associated   **\n"
+         "**  to the degree sequence provided as input.                     **\n"
+         "**                                                                **\n"
+         "**  The degree sequence is a file with format:                    **\n"
+         "**                                                                **\n"
+         "**                           k_1                                  **\n"
+         "**                           k_2                                  **\n"
+         "**                           k_3                                  **\n"
+         "**                           ....                                 **\n"
+         "**                           k_N                                  **\n"
+         "**                                                                **\n"
+         "**   where 'k_i' is the degree of the i-th node. The program      **\n"
+         "**   prints on output the edge-list of the resulting graph. The   **\n"
+         "**   final graph might contain self-loops and multiple edges.     **\n"
+         "**                                                                **\n"
+         "********************************************************************\n"
+         " This is Free Software - You can use and distribute it under \n"
+         " the terms of the GNU General Public License, version 3 or later\n\n"
+         " Please visit http://www.complex-networks.net for more information\n\n"
+         " (c) Vincenzo Nicosia 2010-2017 (v.nicosia@qmul.ac.uk)\n"
+         "********************************************************************\n\n"
+         );
+  printf("Usage: %s <degs>\n\n" , argv[0]);
+}
+
+
+unsigned int count_stubs(unsigned int *nodes, int N){
+  
+  int i;
+  unsigned int cnt;
+
+  cnt = 0;
+  for (i=0; i<N; i ++){
+    cnt += nodes[i];
+  }
+  return cnt;
+}
+
+
+/* sample a multigraph from the configuration model */
+
+void sample_graph_conf_nocheck(unsigned int *nodes, int N){
+  
+  unsigned int S;
+  unsigned int i, j;
+  unsigned int n_stubs;
+  unsigned int *stubs;
+  unsigned int L1, L2, I1, I2, tmp;
+  
+  n_stubs = count_stubs(nodes, N);
+  
+  if (n_stubs %2){
+    fprintf(stderr, "The sequence is not even!\n");
+    exit(3);
+  }
+
+  stubs = malloc(n_stubs * sizeof(unsigned int));
+  
+  /*
+   * We first initialize the stubs
+   */
+  
+  S = 0;
+  for(i=0; i<N; i ++){
+    for(j=0; j<nodes[i]; j ++){
+      stubs[S] = i;
+      S += 1;
+    }
+  }
+  while (S > 0){
+    /* sample the first stub */
+    L1 = rand() % S;
+    I1 = stubs[L1];
+    S -= 1;
+
+    /* sample the second stub */
+    L2 = rand() % S;
+    I2 = stubs[L2];
+    S -= 1;
+    
+    if (L1 == L2){/* If L1 and L2 are the same element, discard the
+                     sample */
+      /* reset S to the value it had before */
+      S += 2;
+      continue;
+    }
+
+    if (I1 > I2){
+      tmp = I2;
+      I2 = I1;
+      I1 = tmp;
+    }
+    
+    printf("%d %d\n", I1, I2);
+    /* And then we remove the two stubs */
+    stubs[L1] = stubs[S+1];
+    stubs[L2] = stubs[S];
+  }
+  free(stubs);
+}
+
+
+
+int main(int argc, char *argv[]){
+  
+  unsigned int  *nodes= NULL;
+  int N;
+  FILE *filein;
+
+  if (argc < 2){
+    usage(argv);
+    exit(1);
+  }
+  
+  srand(time(NULL));
+
+  if (!strcmp(argv[1], "-")){
+    /* take the input from STDIN */
+    filein = stdin;
+  }
+  else {
+    filein = openfile_or_exit(argv[1], "r", 2);
+  }
+  
+  N = read_deg_seq(filein, &nodes);
+  fclose(filein);
+  sample_graph_conf_nocheck(nodes, N);
+  free(nodes);
+}
-- 
cgit v1.2.3