First commit on github -- NetBunch 1.0

1 files changed, 215 insertions, 0 deletions

diff --git a/src/kruskal/kruskal.c b/src/kruskal/kruskal.c
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+/**
+ *  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 finds the minimum/maximum spanning tree of a graph
+ *  given as input, using the Kruskal's algorithm 
+ *
+ *
+ *  References:
+ *  
+ * [1] J. B. Kruskal. "On the shortest spanning subtree of a graph and
+ *     the traveling sales-man problem". P. Am. Math. Soc. 7 (1956),
+ *     48-48.  
+ *
+ */
+
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "dset.h"
+#include "gen_heap.h"
+#include "utils.h"
+#include "edge_w_funs.h"
+
+
+void usage(int argc, char *argv[]){
+
+  printf("********************************************************************\n"
+         "**                                                                **\n"
+         "**                        -*-   kruskal  -*-                      **\n"
+         "**                                                                **\n"
+         "**   Find the minimum/maximum spanning tree of a weighted graph   **\n"
+         "**   'graph_in' provided as input.                                **\n"
+         "**                                                                **\n"
+         "**   The input file 'graph_in' is a weighted edge-list:           **\n"
+         "**                                                                **\n"
+         "**                        I_1 J_1 W_1                             **\n"
+         "**                        I_2 J_2 W_2                             **\n"
+         "**                        I_3 J_3 W_3                             **\n"
+         "**                        ... ...                                 **\n"
+         "**                        I_K J_K W_K                             **\n"
+         "**                                                                **\n"
+         "**    The program computes by default the minimum spanning tree   **\n"
+         "**    of 'graph_in', unless the second parameter 'MAX' is         **\n"
+         "**    specified.                                                  **\n"
+         "**                                                                **\n"
+         "**    The program prints on STDOUT the weighted edge-list of the  **\n"
+         "**    minimum/maximum spanning tree of 'graph_in'.                **\n"
+         "**                                                                **\n"
+         "**    If 'graph_in' is an unweighted graph, the program prints    **\n"
+         "**    on output one of the spanning trees of the 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"
+         " Please visit http://www.complex-networks.net for more information\n\n"
+         " (c) Vincenzo Nicosia 2009-2017 (v.nicosia@qmul.ac.uk)\n"
+         "********************************************************************\n\n"
+         );
+  printf("Usage: %s <graph_in> [MAX]\n", argv[0]);
+}
+
+
+void kruskal(gen_heap_t *h, unsigned int N){
+  
+  dset_t *nodes, set1, set2;
+  edge_w_t *elem;
+  unsigned int i;
+  
+  
+  nodes = malloc(N * sizeof(dset_t));
+  
+  for(i=0; i<N; i++){
+    nodes[i] = NULL;
+    dset_makeset(nodes + i);
+  }
+  
+  while(! gen_heap_delete(h, (void**)(&elem))){
+    /* get the next edge */
+    set1 = dset_find(nodes[elem->i]);
+    set2 = dset_find(nodes[elem->j]);
+    /* if i and j do not belong to the same disjoint set...*/
+    if (set1 != set2){
+      /* ... the edge (i,j) belongs to the spanning tree, */
+      /* so we print it...*/
+      print_elem_edge_w(elem);
+      /* ...then merge the two sets... */
+      dset_union(nodes[elem->i], nodes[elem->j]);
+    }
+    free(elem);
+  }
+  /* We now destroy all the disjoint sets... */
+  for (i=0;i<N;i++){
+    dset_destroy(nodes[i]);
+  }
+  free(nodes);
+  
+}
+
+void load_edges_into_heap(FILE *filein, gen_heap_t *h){
+  
+  char buff[256];
+  char *ptr;
+  edge_w_t *elem;
+  
+  
+  while(fgets(buff, 256, filein)){
+    if (buff[0] == '#')
+      continue;
+    elem = malloc(sizeof(edge_w_t));
+    ptr = strtok(buff, " "); /* read the first node */
+    VALID_PTR_OR_EXIT(ptr, 7);
+    elem->i = atoi(ptr);
+    ptr = strtok(NULL, " "); /* read the second node */
+    VALID_PTR_OR_EXIT(ptr, 7);
+    elem->j = atoi(ptr);
+    ptr = strtok(NULL, " "); /* read the weight */
+    if (!ptr)
+      /* if no weight is specified, assume it is set to 1.0 */
+      elem->w = 1.0;
+    else
+      elem->w = atof(ptr);
+    /* put the edge in the heap */
+    gen_heap_insert(h, elem);
+  }
+  
+}
+
+int count_num_lines(FILE *filein){
+  
+  int i, ch ;
+
+  i = 0;
+  
+  while ((ch = fgetc(filein)) != EOF){
+      if (ch == '\n')
+        i ++;
+  }
+  rewind(filein);
+  return i;
+}
+
+
+int main(int argc, char *argv[]){
+  
+  gen_heap_t *h;
+  unsigned int N;
+  FILE *filein;
+  char htype;
+  gen_heap_func_t  *funs;
+  
+  if(argc < 2){
+    usage(argc, argv);
+    exit(1);
+  }
+
+  htype = MIN_HEAP;
+  if (argc > 2 && !my_strcasecmp(argv[2], "MAX")){
+    htype = MAX_HEAP;
+  }
+
+  /* Initialisation of functions for gen_heap*/
+  funs = malloc(sizeof(gen_heap_func_t));
+  (*funs).compare = compare_edge_w;
+  (*funs).alloc_vector = alloc_vector_edge_w;
+  (*funs).dealloc_vector = dealloc_vector_edge_w;
+  (*funs).dealloc_elem = dealloc_elem_edge_w;
+  (*funs).print_elem = print_elem_edge_w;
+
+
+  
+  filein = openfile_or_exit(argv[1], "r", 2);
+  
+  N = count_num_lines(filein);
+
+  h = gen_heap_init(N, htype, funs);
+  
+  load_edges_into_heap(filein, h);
+
+  fclose(filein);
+  
+  kruskal(h, N);
+  gen_heap_destroy(h);
+  free(funs);
+}