/* -*- mode: C -*-  */
/* 
   IGraph library.
   Copyright (C) 2010-2012  Gabor Csardi <csardi.gabor@gmail.com>
   334 Harvard st, Cambridge MA, 02139 USA
   
   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 2 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, write to the Free Software
   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 
   02110-1301 USA

*/

#include <igraph.h>
#include <stdio.h>

int main() {
  igraph_t g, sub;
  igraph_vector_t map, invmap;
  igraph_vector_t keep;
  long int i;
  
  igraph_small(&g, 9, IGRAPH_DIRECTED, 0,1, 0,2, 1,3, 2,3,
	       1,4,4,2, 1,5,5,2, 1,6,6,2, 1,7,7,2, 1,8,8,2,
	       -1);
  igraph_vector_init(&map, 0);
  igraph_vector_init(&invmap, 0);
  igraph_vector_init(&keep, igraph_vcount(&g));
  for (i=0; i<igraph_vector_size(&keep); i++) {
    VECTOR(keep)[i] = i;
  }

  igraph_induced_subgraph_map(&g, &sub, 
			      igraph_vss_vector(&keep),
			      IGRAPH_SUBGRAPH_COPY_AND_DELETE,
			      &map, &invmap);
  
  printf("Map:         "); igraph_vector_print(&map);
  printf("Inverse map: "); igraph_vector_print(&invmap);
  igraph_write_graph_edgelist(&sub, stdout);

  igraph_vector_destroy(&keep);
  igraph_vector_destroy(&map);
  igraph_vector_destroy(&invmap);
  
  igraph_destroy(&sub);
  igraph_destroy(&g);

  return 0;
}
