adjacency.rb in rgl-0.4.0

- old
+ new

@@ -1,8 +1,8 @@
 # adjacency.rb
 # 
-# $Id: adjacency.rb,v 1.11 2008/03/02 13:45:43 monora Exp $
+# $Id: adjacency.rb,v 1.12 2008/08/23 05:37:05 javanthropus Exp $
 # 
 # The DirectedAdjacencyGraph class implements a generalized adjacency list
 # graph structure.  An AdjacencyGraph is basically a two-dimensional structure
 # (ie, a list of lists).  Each element of the first dimension represents a
 # vertex.  Each of the vertices contains a one-dimensional structure that is
@@ -171,9 +171,10 @@
     # Convert a general graph to an AdjacencyGraph.  If the graph is directed,
     # returns a DirectedAdjacencyGraph; otherwise, returns an AdjacencyGraph.
 
     def to_adjacency
       result = (directed? ? DirectedAdjacencyGraph : AdjacencyGraph).new
+      each_vertex { |v| result.add_vertex(v) }
       each_edge { |u,v| result.add_edge(u, v) }
       result
     end
 
     # Return a new DirectedAdjacencyGraph which has the same set of vertices.