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/ba/ba.c | 185 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 185 insertions(+)
 create mode 100644 src/ba/ba.c

(limited to 'src/ba/ba.c')

diff --git a/src/ba/ba.c b/src/ba/ba.c
new file mode 100644
index 0000000..e395d6d
--- /dev/null
+++ b/src/ba/ba.c
@@ -0,0 +1,185 @@
+/**
+ *  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 grows a network with N nodes using the linear
+ *  preferential attachment model proposed by Barabasi and
+ *  Albert. Each new node creates m links, and the initial (seed)
+ *  network is a ring of n0>=m nodes.
+ *
+ *
+ *  References:
+ *
+ *  [1] A.-L. Barabasi, R. Albert, "Emergence of scaling in random
+ *  networks", Science 286, 509-512 (1999).
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+void usage(char *argv[]){
+  printf("********************************************************************\n"
+         "**                                                                **\n"
+         "**                        -*-     ba     -*-                      **\n"
+         "**                                                                **\n"
+         "**   Grow a scale-free network of 'N' nodes using the linear      **\n"
+         "**   preferential attachment model (Barabasi-Albert).             **\n"
+         "**   The initial network is a ring of 'n0' nodes, and each new    **\n"
+         "**   node creates 'm' edges.                                      **\n"
+         "**                                                                **\n"
+         "**   The program prints on STDOUT the edge-list of the final      **\n"
+         "**   graph.                                                       **\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"
+         " (c) Vincenzo Nicosia 2010-2017 (v.nicosia@qmul.ac.uk)\n\n"
+         "********************************************************************\n\n"
+         );
+  printf("Usage: %s <N> <m> <n0>\n", argv[0]);
+
+}
+
+
+
+int init_network(unsigned int **S, unsigned int n0){
+  
+  int n;
+
+  for(n=0; n<n0; n++){
+    S[0][n] = n;
+    S[1][n] = (n+1) % n0;
+  }
+  return n;
+}
+
+int select_neighbour(unsigned int **S, unsigned int S_num){
+  
+  int d;
+  
+  d = rand()%(S_num * 2);
+  if (d < S_num)
+    return S[0][d];
+  else{
+    return S[1][d-S_num];
+  }
+}
+
+/* check if 'd' is already a neighbour of 'i' */
+
+int already_neighbour(unsigned int **S, unsigned int S_num, unsigned int j, unsigned int d){
+
+   int i;
+
+   for(i=S_num; i< S_num + j; i ++){
+     if (S[1][i] == d)
+       return 1;
+   }
+   return 0;
+}
+
+unsigned int grow_ba_network(unsigned int **S, unsigned int N,
+                             unsigned int m, unsigned int n0, unsigned int S_num){
+  
+  int i, j;
+  int n, d;
+  
+  for(i=0; i<N-n0; i++){
+    /* Let's add a new node */
+    n = n0 + i; /* This is the id of the new node */
+    for(j=0; j<m; j++){
+      S[0][S_num+j] = n;
+      d = select_neighbour(S, S_num);
+      while(already_neighbour(S, S_num, j, d)){
+        d = select_neighbour(S, S_num);
+      }
+      S[1][S_num + j] = d;
+    }
+    S_num += m;
+  }
+  return S_num;
+}
+
+
+
+int main(int argc, char *argv[]){
+  
+  unsigned int **S;
+  unsigned int S_num, S_size, i;
+  int m, n0, N;
+  
+  if (argc < 4){
+    usage(argv);
+    exit(1);
+  }
+
+  srand(time(NULL));
+
+  N = atoi(argv[1]);
+  m = atoi(argv[2]);
+  n0 = atoi(argv[3]);
+  S_size = (N+n0) * m ;
+
+  if (N < 1){
+    fprintf(stderr, "N must be positive\n");
+    exit(1);
+  }
+  if(m > n0){
+    fprintf(stderr, "n0 cannot be smaller than m\n");
+    exit(1);
+
+  }
+  if (n0<1){
+    fprintf(stderr, "n0 must be positive\n");
+    exit(1);
+  }
+  
+  if (m < 1){
+    fprintf(stderr, "m must be positive\n");
+    exit(1);
+  }
+  
+  S = malloc(2 * sizeof(unsigned int*));
+  S[0] = malloc(S_size * sizeof(unsigned int));
+  S[1] = malloc(S_size * sizeof(unsigned int));
+  
+  S_num = init_network(S, n0);
+  S_num = grow_ba_network(S, N, m, n0, S_num);
+  for(i=0; i<S_num; i ++){
+    printf("%d %d\n",S[0][i], S[1][i]);
+  }
+  free(S[0]);
+  free(S[1]);
+  free(S);
+}
-- 
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