From: Neil Smith <neil.github@njae.me.uk>
Date: Fri, 10 Feb 2012 20:02:29 +0000 (+0000)
Subject: Product graphs working initially
X-Git-Url: https://git.njae.me.uk/?p=graph.njae.git;a=commitdiff_plain;h=369a49ecb7cf80a1d93d7bacc0ef419320295ca1

Product graphs working initially
---

diff --git a/lib/graph.njae/edge.rb b/lib/graph.njae/edge.rb
index 814360b..4a1ba79 100644
--- a/lib/graph.njae/edge.rb
+++ b/lib/graph.njae/edge.rb
@@ -20,6 +20,7 @@ module GraphNjae
     def <<(other)
       c = Connection.new
       c.end = other
+      other.edges << self unless other.edges.include? self
       self.connections << c
       self
     end
@@ -38,8 +39,8 @@ module GraphNjae
   # A connection between an Edge and a Vertex.The connection can have arbitrary attributes,
   # treated as method names.
   class Connection < OpenStruct
-    def initialize
-      super
+    def initialize(values = {})
+      super(values)
       self
     end
   end
diff --git a/lib/graph.njae/graph.rb b/lib/graph.njae/graph.rb
index b1de59b..09d6137 100644
--- a/lib/graph.njae/graph.rb
+++ b/lib/graph.njae/graph.rb
@@ -24,18 +24,38 @@ module GraphNjae
       self
     end
     
+    # Connects two vertices, creating and storing a new edge
+    # Also adds the vertices, unless they're already in the graph
+    def connect(vertex1, vertex2)
+      self.vertices << vertex1 unless self.vertices.include? vertex1
+      self.vertices << vertex2 unless self.vertices.include? vertex2
+      edge = Edge.new
+      self.edges << edge
+      edge << vertex1 << vertex2
+    end
+    
     # Form a product graph of this graph and the other.
     # Return the new graph.
     def product(other)
       product_graph = Graph.new
       self.vertices.each do |v1|
         other.vertices.each do |v2|
-          product_vertex = Vertex.new
-          product_vertex.left_node = v1
-          product_vertex.right_node = v2
-          product_graph << product_vertex
+          product_graph << Vertex.new({:g1_vertex => v1, :g2_vertex => v2})
+        end
+      end
+      self.edges.each do |e1|
+        e1_vertices = e1.vertices
+        other.edges.each do |e2|
+          e2_vertices = e2.vertices
+          source = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[0] and v.g2_vertex == e2_vertices[0]}
+          destination = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[1] and v.g2_vertex == e2_vertices[1]}
+          pe1 = product_graph.connect source, destination
+          source = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[0] and v.g2_vertex == e2_vertices[1]}
+          destination = product_graph.vertices.find {|v| v.g1_vertex == e1_vertices[1] and v.g2_vertex == e2_vertices[0]}
+          pe2 = product_graph.connect source, destination
         end
       end
+      product_graph
     end
     
   end # class
diff --git a/lib/graph.njae/vertex.rb b/lib/graph.njae/vertex.rb
index 6b34351..aeabe30 100644
--- a/lib/graph.njae/vertex.rb
+++ b/lib/graph.njae/vertex.rb
@@ -17,8 +17,8 @@ module GraphNjae
     def connect(other)
       e = Edge.new
       e << self << other
-      self.edges << e
-      other.edges << e unless self === other
+      # self.edges << e
+      # other.edges << e unless self === other
       e
     end
     
diff --git a/spec/graph/edge_spec.rb b/spec/graph/edge_spec.rb
index d139667..8373864 100644
--- a/spec/graph/edge_spec.rb
+++ b/spec/graph/edge_spec.rb
@@ -35,11 +35,13 @@ module GraphNjae
         e.should have(1).connections
         e.should have(1).vertices
         e.vertices.should include(v1)
+        v1.edges.should include(e)
         e << v2
         e.should have(2).connections
         e.should have(2).vertices
         e.vertices.should include(v1)
         e.vertices.should include(v2)
+        v2.edges.should include(e)
       end
       
       it "adds several vertices to an edge" do
diff --git a/spec/graph/graph_spec.rb b/spec/graph/graph_spec.rb
index 5da61f5..670d252 100644
--- a/spec/graph/graph_spec.rb
+++ b/spec/graph/graph_spec.rb
@@ -84,8 +84,51 @@ module GraphNjae
 
     describe "connect" do
       it "adds and records an edge between vertices" do
+        g.vertices.should be_empty
+        g.edges.should be_empty
+        v1 = Vertex.new(:name => :v1)
+        v2 = Vertex.new(:name => :v2)
+        g.connect(v1, v2)
+        
+        g.should have(2).vertices
+        g.vertices.should include(v1)
+        g.vertices.should include(v2)
+        g.should have(1).edges
       end
     end # #connect
     
+    describe "product" do
+      it "finds a product graph of a pair of one-vertex graphs" do
+        g1 = Graph.new
+        g2 = Graph.new
+        g1v1 = Vertex.new
+        g1 << g1v1
+        g2v1 = Vertex.new
+        g2 << g2v1
+        product = g1.product g2
+        
+        product.should have(1).vertices
+        product.vertices.first.g1_vertex.should == g1v1
+        product.vertices.first.g2_vertex.should == g2v1
+        product.edges.should be_empty
+      end
+
+      it "finds a product graph of a pair of simple graphs" do
+        g1 = Graph.new
+        g2 = Graph.new
+        g1v1 = Vertex.new(:name => :g1v1)
+        g1v2 = Vertex.new(:name => :g1v2)
+        g1.connect(g1v1, g1v2)
+        g2v1 = Vertex.new(:name => :g2v1)
+        g2v2 = Vertex.new(:name => :g2v2)
+        g2.connect(g2v1, g2v2)
+        pg = g1.product g2
+        
+        pg.should have(4).vertices
+        pg.should have(2).edges
+      end
+
+    end
+    
   end
 end