Method: IGraph#initialize

Defined in:
ext/cIGraph.c

#new(edges, directed) ⇒ IGraph

Creates a new IGraph graph with the edges specified in the edges Array. The first two elements define the first edge (the order is from,to for directed graphs). The next two define the second edge and so on. The Array should contain an even number of elements. Graph elements can be any ruby object.

The boolean value directed specifies whether a directed or undirected graph is created.

Example:

IGraph.new([1,2,3,4],true)

Creates a graph with four vertices. Vertex 1 is connected to vertex 2. Vertex 3 is connected to vertex 4.



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# File 'ext/cIGraph.c', line 78

VALUE cIGraph_initialize(int argc, VALUE *argv, VALUE self){

  igraph_t *graph;
  igraph_vector_t edge_v;
  VALUE vertex;
  VALUE directed;
  VALUE edges;
  VALUE attrs;
  VALUE v_ary;
  int vertex_n = 0;
  int current_vertex_id;
  int i;

  igraph_vector_ptr_t vertex_attr;
  igraph_vector_ptr_t edge_attr;

  igraph_i_attribute_record_t v_attr_rec;
  v_attr_rec.name  = "__RUBY__";
  v_attr_rec.type  = IGRAPH_ATTRIBUTE_PY_OBJECT;
  v_attr_rec.value = (void*)rb_ary_new();

  igraph_i_attribute_record_t e_attr_rec;
  e_attr_rec.name  = "__RUBY__";
  e_attr_rec.type  = IGRAPH_ATTRIBUTE_PY_OBJECT;
  e_attr_rec.value = (void*)rb_ary_new();

  rb_scan_args(argc,argv,"12", &edges, &directed, &attrs);

  //Initialize edge vector
  IGRAPH_FINALLY(igraph_vector_destroy,&edge_v);
  IGRAPH_FINALLY(igraph_vector_ptr_destroy,&vertex_attr);
  IGRAPH_FINALLY(igraph_vector_ptr_destroy,&edge_attr);

  IGRAPH_CHECK(igraph_vector_init_int(&edge_v,0));

  IGRAPH_CHECK(igraph_vector_ptr_init(&vertex_attr,0));
  IGRAPH_CHECK(igraph_vector_ptr_init(&edge_attr,0));

  Data_Get_Struct(self, igraph_t, graph);

  v_ary = rb_ary_new();

  if(!directed)
    IGRAPH_CHECK(igraph_to_undirected(graph,IGRAPH_TO_UNDIRECTED_COLLAPSE));

  //Loop through objects in edge Array
  for (i=0; i<RARRAY(edges)->len; i++) {
    vertex = RARRAY(edges)->ptr[i];
    if(rb_ary_includes(v_ary,vertex)){
      //If @vertices includes this vertex then look up the vertex number
      current_vertex_id = NUM2INT(rb_funcall(v_ary,rb_intern("index"),1,vertex));
    } else {
      //Otherwise add to the list of vertices
      rb_ary_push(v_ary,vertex);
      current_vertex_id = vertex_n;
      vertex_n++;
      
      //Add object to list of vertex attributes
      rb_ary_push((VALUE)v_attr_rec.value,vertex);
      
    }
    IGRAPH_CHECK(igraph_vector_push_back(&edge_v,current_vertex_id));
    if (i % 2){
      if (attrs != Qnil){
	rb_ary_push((VALUE)e_attr_rec.value,RARRAY(attrs)->ptr[i/2]);
      } else {
	rb_ary_push((VALUE)e_attr_rec.value,Qnil);
      }
    }
  }

  IGRAPH_CHECK(igraph_vector_ptr_push_back(&vertex_attr, &v_attr_rec));
  IGRAPH_CHECK(igraph_vector_ptr_push_back(&edge_attr,   &e_attr_rec));

  if(igraph_vector_size(&edge_v) > 0){
    IGRAPH_CHECK(igraph_add_vertices(graph,vertex_n,&vertex_attr));
    IGRAPH_CHECK(igraph_add_edges(graph,&edge_v,&edge_attr));
  }

  igraph_vector_destroy(&edge_v);
  igraph_vector_ptr_destroy(&vertex_attr);
  igraph_vector_ptr_destroy(&edge_attr);

  IGRAPH_FINALLY_CLEAN(3);

  return self;

}