First commit on github -- NetBunch 1.0

1 files changed, 277 insertions, 0 deletions

diff --git a/src/components/strong_conn.c b/src/components/strong_conn.c
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+++ b/src/components/strong_conn.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 (size of the) strongly connected components
+ *  of a directed graph given as input. We use the Kosaraju-Sharir
+ *  algorithm, which performs two DFS scans of the graph, the first
+ *  time using the original DFS algorithm on the graph, and the second
+ *  time using the transposed graph and a slightly modified version of
+ *  "components", which traverses the nodes of the graph in descending
+ *  order of finishing time.
+ *
+ *    
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "utils.h"
+
+
+void usage(char *argv[]){
+  printf("********************************************************************\n"
+         "**                                                                **\n"
+         "**                      -*-  strong_conn  -*-                     **\n"
+         "**                                                                **\n"
+         "**   Find the strongly connected components of a directed graph   **\n"
+         "**   and print on output their size and/or the list of nodes      **\n"
+         "**   belonging to each component. The first parameter 'graph_in'  **\n"
+         "**   is the name of the file containing the edge list of the      **\n"
+         "**   graph.                                                       **\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 the SIZE of each strongly       **\n"
+         "**   connected component of the graph, one per line:              **\n"
+         "**                                                                **\n"
+         "**      size_1                                                    **\n"
+         "**      size_2                                                    **\n"
+         "**      size_3                                                    **\n"
+         "**                                                                **\n"
+         "**    The sizes are in no particular order.                       **\n"
+         "**                                                                **\n"
+         "**    If 'SHOW' is given as second argument, the list of nodes    **\n"
+         "**    belonging to each component is printed as well, in the      **\n"
+         "**    format:                                                     **\n"
+         "**                                                                **\n"
+         "**      size_1: node_1 node_2 node_3 ....                         **\n"
+         "**      size_2: node_1 node_2 node_3 ....                         **\n"
+         "**      size_3: node_1 node_2 node_3 ....                         **\n"
+         "**                                                                **\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 <graph_in> [SHOW]\n\n" , argv[0]);
+}
+
+int dfs(unsigned int i, unsigned int *J_slap, unsigned int *r_slap, 
+        unsigned int N, unsigned int nc, 
+        unsigned int *ic, unsigned int *f, 
+        char reset){
+  
+  static unsigned int time = 0;
+  unsigned int j, s;
+  
+  if(reset){
+    time = 0;
+  }
+  
+  ic[i] = nc;
+  s = 1;
+  
+  for(j=r_slap[i]; j<r_slap[i+1]; j++){
+    if (ic[J_slap[j]] == 0){
+      s += dfs(J_slap[j], J_slap, r_slap, N, nc, ic, f, 0);
+    }
+  }
+  f[time] = i;
+  time += 1;
+  return s;
+}
+
+
+
+/**
+ * 
+ * Find all the components of the given graph
+ *
+ */
+
+int components(unsigned int *J_slap, unsigned int *r_slap,
+                unsigned int N, unsigned int **ic, 
+                unsigned int **f, unsigned int **sizes){
+
+  unsigned int nc, s;
+  unsigned int i;
+
+  *ic = malloc(N * sizeof(unsigned int));
+  *f = malloc(N * sizeof(unsigned int));
+  *sizes = malloc(N * sizeof(unsigned int));
+  
+  for(i=0; i<N; i++){
+    (*ic)[i] = 0;
+    (*f)[i] = 0;
+  }
+  nc = 0;
+  for(i=0; i<N; i++){
+    while( (*ic) [i] != 0 && i < N)
+      i += 1;
+    if (i == N)
+      break;
+    nc += 1;
+    if (nc ==1){
+      s = dfs(i, J_slap, r_slap, N, nc, *ic, *f, 1);
+    }
+    else{
+      s = dfs(i, J_slap, r_slap, N, nc, *ic, *f, 0);
+    }
+    //printf("s: %d\n", s);
+    (*sizes)[nc] = s;
+  }
+  return nc;
+}
+
+
+/**
+ * 
+ * Find the components of the transposed graph, where the nodes are
+ * visited in descending order of their finishing time 
+ *
+ */
+
+int components_rev(unsigned int *J_slap, unsigned int *r_slap,
+                   unsigned int N, unsigned int **ic, 
+                   unsigned int *f, unsigned int **f_T, unsigned int **sizes){
+  
+  unsigned int nc, s;
+  unsigned int  idx;
+  int i;
+
+  *ic = malloc(N * sizeof(unsigned int));
+  *f_T = malloc(N * sizeof(unsigned int));
+  *sizes = malloc((N+1) * sizeof(unsigned int));
+  
+  for(i=0; i<N; i++){
+    (*ic)[i] = 0;
+  }
+  nc = 0;
+  for(i=N-1; i>=0; i--){
+    idx = f[i];
+    while( i >0 && (*ic) [idx] != 0 ){
+      i -= 1;
+      idx = f[i];
+    }
+    if (i < 0)
+      break;
+    nc += 1;
+    if (nc == 1){
+      s = dfs(idx, J_slap, r_slap, N, nc, *ic, *f_T, 1);
+    }
+    else{
+      s = dfs(idx, J_slap, r_slap, N, nc, *ic, *f_T, 1);
+    }
+    (*sizes)[nc] = s;
+  }
+  return nc;
+}
+
+
+
+int main(int argc, char *argv[]){
+
+
+  FILE *filein;
+  unsigned int N, K, N1, N2;
+  unsigned int *I, *J, *J_slap, *r_slap, *J_slap_T, *r_slap_T;
+  unsigned int *ic, *f, *sizes, *ic_T, *f_T, *sizes_T;
+  unsigned int i, j, nc_T;
+  char show = 0;
+
+  if (argc < 2){
+    usage(argv);
+    exit(1);
+  }
+  if (argc == 3 && !my_strcasecmp("SHOW", argv[2])){
+    show = 1;
+  }  
+  
+  if (!strcmp(argv[1], "-")){
+    /* take the input from STDIN */
+    filein = stdin;
+  }
+  else {
+    filein = openfile_or_exit(argv[1], "r", 2);
+  }
+
+
+  I = J = NULL;
+  K = read_ij(filein, &I, &J);
+  J_slap = J_slap_T = NULL;
+  r_slap = r_slap_T = NULL;
+  /* obtain the SLAP representation of the graph */
+  N1 = convert_ij2slap(I, J, K, &r_slap, &J_slap);
+  /* obtain the SLAP representation of the transposed graph */
+  N2 = convert_ij2slap(J, I, K, &r_slap_T, &J_slap_T);
+  N = N1 >= N2 ? N1 : N2;
+  components(J_slap, r_slap, N, &ic, &f, &sizes);
+
+  fclose(filein);
+
+  
+  nc_T = components_rev(J_slap_T, r_slap_T, N, &ic_T, f, &f_T, &sizes_T);
+
+  for(i=1; i<=nc_T; i++){
+    printf("%d", sizes_T[i]);
+    if (show){
+      printf(":");
+        for(j=0; j<N; j++){
+          if (ic_T[j] == i){
+            printf(" %d", j);
+          }
+        }
+      printf("\n");
+    }
+    else{
+      printf("\n");
+    }
+  }
+  free(J_slap);
+  free(r_slap);
+  free(J_slap_T);
+  free(r_slap_T);
+  free(ic);
+  free(f); 
+  free(sizes); 
+  free(ic_T);
+  free(f_T); 
+  free(sizes_T); 
+  free(I);
+  free(J);
+}