First commit on github -- NetBunch 1.0

1 files changed, 259 insertions, 0 deletions

diff --git a/src/shortest/shortest.c b/src/shortest/shortest.c
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+++ b/src/shortest/shortest.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 computes the distance from a given node to all the
+ *  other nodes of an undirected graph, using the Breadth-First Search
+ *  algorithm. 
+ *
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "utils.h"
+
+
+void usage(char *argv[]){
+  printf("********************************************************************\n"
+         "**                                                                **\n"
+         "**                        -*-  shortest  -*-                      **\n"
+         "**                                                                **\n"
+         "**  Compute the distance from the given 'node' to all the other   **\n"
+         "**  nodes of an undirected graph. The first parameter 'graph_in'  **\n"
+         "**  is the name of the file containing the edge list of the       **\n"
+         "**  graph. The second parameter 'node' is the label of the node   **\n"
+         "**  for which we want to compute the distances to all the other   **\n"
+         "**  nodes.                                                        **\n"
+         "**                                                                **\n"
+         "**  If 'graph_in' is equal to '-' (dash), read the edge list      **\n"
+         "**  from standard input (STDIN)                                   **\n"
+         "**                                                                **\n"
+         "**  The program prints on output a row of values:                 **\n"
+         "**                                                                **\n"
+         "**        d0 d1 d2 d3 d4......                                    **\n"
+         "**                                                                **\n"
+         "**  where d0 is the distance between 'node' and '0', 'd1' is the  **\n"
+         "**  distance between 'node' and '1', and so on.                   **\n"
+         "**                                                                **\n"         
+         "**  If the third parameter is equal to 'SHOW', the program will   **\n"         
+         "**  dump all the shortest paths from 'node' to all the other      **\n"
+         "**  nodes on the standard error (STDERR).                         **\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> <node> [SHOW]\n\n" , argv[0]);
+}
+
+
+/*
+ * Add 'k' to a list of predecessors
+ */
+
+void add_predecessor(unsigned int **pred, unsigned int k){
+  
+  (*pred)[0] += 1;
+  *pred = realloc(*pred, ((*pred)[0] + 1)  * sizeof(unsigned int));
+  (*pred)[ (*pred)[0] ] = k;
+}
+
+
+
+/*
+ *  
+ * This is the implementation of the Breadth-First Search algorithm
+ * (BFS) to compute the shortest paths, and the distances, between a
+ * given node 'i' and all the other nodes of a graph. 
+ * 
+ */
+unsigned int** compute_shortest_paths(unsigned int N, unsigned int *J_slap, unsigned int *r_slap, 
+                            unsigned int i, unsigned int **dist){
+  
+  unsigned int j, k, cur_node;
+  unsigned int  *marked, **preds;
+  unsigned int d;
+  unsigned int n, nd, ndp;
+  
+  *dist = malloc(N * sizeof(unsigned int));
+  marked = malloc(N * sizeof(unsigned int));
+  preds = malloc(N * sizeof(unsigned int *));
+  
+  for(j=0; j<N; j ++){
+    (*dist)[j] = N;
+    preds[j] = malloc(sizeof(unsigned int));
+    preds[j][0] = 0; /* The list of predecessors is empty! */
+  }
+  (*dist)[i] = 0;
+  marked[0] = i;
+  d = 0;
+  n = 0;
+  nd = 1;
+  ndp = 0;
+  while (d<N && nd > 0){
+    for(k = n; k< n+nd; k ++){
+      cur_node = marked[k];
+      for (j=r_slap[cur_node]; j<r_slap[cur_node +1] ; j++){
+        if ( (*dist)[ J_slap[j] ] == d+1){
+          add_predecessor((unsigned int **)(preds + J_slap[j]), cur_node);
+        }
+        if ( (*dist)[ J_slap[j] ] == N){
+          (*dist)[ J_slap[j] ] = d+1;
+          marked[n + nd + ndp] = J_slap[j];
+          add_predecessor(preds + J_slap[j], cur_node);
+          ndp +=1;
+        }
+      }
+    
+    }
+    n = n + nd;
+    nd = ndp;
+    ndp = 0;
+    d += 1; 
+  }
+  free(marked);
+  return preds;
+}
+
+/*
+ * Dump on output the distances between 'node' and all the other nodes
+ * of the graph
+ *
+ */
+
+void dump_dists(unsigned int *dists, unsigned int N){
+
+  unsigned int i;
+  for (i=0; i<N; i++){
+    printf("%d ", dists[i]);
+  }
+  printf("\n");
+}
+
+
+/*
+ * recursively show the shortest paths from 'node' to all the other
+ * nodes ot the graph
+ *
+ */
+void recursive_show_paths(unsigned int **preds, unsigned int N, unsigned int k, 
+                          char *buff, int pos, FILE *fileout){
+  
+  int i;
+  char lbuff[10];
+
+  
+  if (preds[k][0] == 0){
+    sprintf(buff + pos, "%5d\n", k);
+    fprintf(fileout, "%s", buff );
+    return;
+  }
+ 
+  sprintf(lbuff, "%5d  ", k);
+  strncpy(buff + pos, lbuff, 7);
+  for(i=1; i<= preds[k][0]; i ++){
+    recursive_show_paths(preds, N, preds[k][i], buff, pos + 7, fileout);
+  }
+  return;
+}
+
+/*
+ *
+ * This function calls recursive_show_paths() for each of the nodes of
+ * the graph, to dump the shortest paths between 'node' and all the
+ * other nodes of the graph.
+ *
+ */
+
+void show_paths(unsigned int **preds, unsigned int N, FILE *fileout){
+  
+  int j;
+  char buff[256];
+
+  for (j = 0; j<N; j++){
+    if (preds[j][0] > 0)
+      recursive_show_paths(preds, N, j, buff, 0, fileout);
+  }
+  
+}
+
+int main(int argc, char *argv[]){
+  
+  unsigned int *J_slap=NULL, *r_slap=NULL;
+  unsigned int K, N, i;
+  unsigned int **preds, *dists=NULL;
+  FILE *filein;
+  
+  if (argc < 3){
+    usage(argv);
+    exit(1);
+  }
+
+  if (!strcmp(argv[1], "-")){
+    /* take the input from STDIN */
+    filein = stdin;
+  }
+  else {
+    filein = openfile_or_exit(argv[1], "r", 2);
+  }
+  
+  read_slap(filein, &K, &N, &J_slap, &r_slap);
+  i = atoi(argv[2]);
+  if (i>N){
+    printf("Node id '%d' does not exist!!!! Exiting....\n", i);
+    exit(3);
+  }
+
+  fclose(filein);
+  
+  preds = compute_shortest_paths(N, J_slap, r_slap, i, &dists);
+  dump_dists(dists, N);
+  /* check if we should dump the shortest paths on stderr */
+  if (argc > 3 && !strcmp(argv[3], "SHOW")){
+    show_paths(preds, N, stderr);
+  }
+
+  /* Cleanup */
+
+  for (i=0; i<N; i++){
+    free(preds[i]);
+  }
+  free(preds);
+  free(dists);
+  free(J_slap);
+  free(r_slap);
+}