igraph/ext/cIGraph_basic_query.c

#include "igraph.h"
#include "ruby.h"
#include "cIGraph.h"

/* call-seq:
 *   graph.vcount() -> Fixnum
 *
 * Returns the number of vertices in the IGraph object.
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.vcount # returns 4
 *
 */

VALUE cIGraph_vcount(VALUE self){
  igraph_t *graph;

  Data_Get_Struct(self, igraph_t, graph);
  return INT2NUM(igraph_vcount(graph));
}

/* call-seq:
 *   graph.ecount() -> Fixnum
 *
 * Returns the number of edges in the IGraph object.
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.ecount # returns 2
 *
 */

VALUE cIGraph_ecount(VALUE self){
  igraph_t *graph;

  Data_Get_Struct(self, igraph_t, graph);
  return INT2NUM(igraph_ecount(graph));
}

/* call-seq:
 *   graph.edge(eid) -> [from,to]
 *
 * Returns an Array comprising the vertices making up the edge represented
 * by the edge id eid. You can find the id of an edge using IGraph#get_eid.
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.edge(1) # returns [1,2]
 *
 */

VALUE cIGraph_edge(VALUE self, VALUE eid){
    igraph_t *graph;
    igraph_integer_t from = 0;
    igraph_integer_t to   = 0;
    VALUE from_r;
    VALUE to_r;

    Data_Get_Struct(self, igraph_t, graph);

    igraph_edge(graph,NUM2INT(eid),&from,&to);

    from_r = cIGraph_get_vertex_object(self,from);
    to_r   = cIGraph_get_vertex_object(self,to);

    return rb_ary_new3(2, from_r, to_r);

}

/* call-seq:
 *   graph.get_eid(from,to,directed) -> Fixnum
 *
 * Returns the edge id of the edge connecting the vertices from and to.
 * directed is a boolean specifying whether to search for directed edges
 * in a directed graph.
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.get_eid(1,2,true) # returns 1
 *
 */
VALUE cIGraph_get_eid(VALUE self, VALUE from, VALUE to, VALUE directed){

    igraph_t *graph;
    igraph_integer_t eid = 0;
    int from_i = 0;
    int to_i = 0;
    igraph_bool_t directed_b = 0;

    Data_Get_Struct(self, igraph_t, graph);

    from_i = cIGraph_get_vertex_id(self,from);
    to_i   = cIGraph_get_vertex_id(self,to);

    if(directed)
      directed_b = 1;
    
    igraph_get_eid(graph,&eid,from_i,to_i,directed_b);
  
    return INT2NUM(eid);

}

/* call-seq:
 *   graph.neighbours(vertex,mode) -> Array
 *
 * Returns an Array of the neighbouring vertices to vertex. mode defines 
 * the way adjacent vertices are searched for directed graphs. It can have 
 * the following values: IGraph::OUT, vertices reachable by an edge from the 
 * specified vertex are searched, IGraph::IN, vertices from which the 
 * specified vertex is reachable are searched. IGraph::ALL, both kind of 
 * vertices are searched. This parameter is ignored for undirected graphs.
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.neighbours(1,IGraph::ALL) # returns [2]
 *
 */
VALUE cIGraph_neighbors(VALUE self, VALUE v, VALUE mode){

  igraph_t *graph;
  igraph_integer_t pnode;
  igraph_neimode_t pmode = NUM2INT(mode);
  igraph_vector_t neis;
  int i;
  VALUE neighbors = rb_ary_new();

  igraph_vector_init_int(&neis,0);

  Data_Get_Struct(self, igraph_t, graph);

  pnode = cIGraph_get_vertex_id(self,v);

  igraph_neighbors(graph,&neis,pnode,pmode);

  for(i=0;i<igraph_vector_size(&neis);i++){
    rb_ary_push(neighbors,cIGraph_get_vertex_object(self,VECTOR(neis)[i]));
  }

  igraph_vector_destroy(&neis);

  return neighbors;

}

/* call-seq:
 *   graph.adjacent(vertex,mode) -> Array
 *
 * Returns an Array of the adjacent edge ids to vertex. mode defines 
 * the way adjacent edges are searched for directed graphs. It can have 
 * the following values: IGraph::OUT means only outgoing edges, IGraph::IN 
 * only incoming edges, IGraph::ALL both. This parameter is ignored for 
 * undirected graphs.
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.adjacent(1,IGraph::ALL) # returns [1]
 *
 */
VALUE cIGraph_adjacent(VALUE self, VALUE v, VALUE mode){

  igraph_t *graph;
  igraph_integer_t pnode;
  igraph_neimode_t pmode = NUM2INT(mode);
  igraph_vector_t eids;
  int i;
  VALUE eids_r = rb_ary_new();

  igraph_vector_init_int(&eids,0);

  Data_Get_Struct(self, igraph_t, graph);

  pnode = cIGraph_get_vertex_id(self,v);

  igraph_adjacent(graph,&eids,pnode,pmode);

  for(i=0;i<igraph_vector_size(&eids);i++){
    rb_ary_push(eids_r,INT2NUM(VECTOR(eids)[i]));
  }

  igraph_vector_destroy(&eids);

  return eids_r;

}

/* call-seq:
 *   graph.is_directed?() -> true/false
 *
 * Returns a boolean specifying whether the graph is directed or not.
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.is_directed? #returns true
 *
 */
VALUE cIGraph_is_directed(VALUE self){
  igraph_t *graph;

  Data_Get_Struct(self, igraph_t, graph);

  return igraph_is_directed(graph) ? Qtrue : Qfalse;

}

/* call-seq:
 *   graph.degree(vs,mode,loops) -> Array
 *
 * Returns an Array of Integers specifying the degree of each of the
 * vertices specified in the vs Array. mode defines the type of the degree. 
 * IGraph::OUT, out-degree, IGraph::IN, in-degree, IGraph::ALL, total degree 
 * (sum of the in- and out-degree). This parameter is ignored for undirected 
 * graphs. 
 *
 * Example:
 *
 *   g = IGraph.new([1,2,3,4],true)
 *   g.is_directed? #returns true
 *
 */
VALUE cIGraph_degree(VALUE self, VALUE v, VALUE mode, VALUE loops){
  igraph_t *graph;
  igraph_vs_t vids;
  igraph_vector_t vidv;
  igraph_neimode_t pmode = NUM2INT(mode);
  igraph_bool_t loop_mode = loops ? 1 : 0;
  igraph_vector_t res;
  int i;
  VALUE degree_r = rb_ary_new();

  //vector to hold the results of the degree calculations
  igraph_vector_init_int(&res,0);

  Data_Get_Struct(self, igraph_t, graph);

  //Convert an array of vertices to a vector of vertex ids
  igraph_vector_init_int(&vidv,0);
  cIGraph_vertex_arr_to_id_vec(self,v,&vidv);
  //create vertex selector from the vecotr of ids
  igraph_vs_vector(&vids,&vidv);

  igraph_degree(graph,&res,vids,pmode,loop_mode);

  for(i=0;i<igraph_vector_size(&res);i++){
    rb_ary_push(degree_r,INT2NUM(VECTOR(res)[i]));
  }

  igraph_vector_destroy(&vidv);
  igraph_vector_destroy(&res);
  igraph_vs_destroy(&vids);

  return degree_r;

}