X-Git-Url: https://git.njae.me.uk/?a=blobdiff_plain;f=lib%2Fgraph.njae%2Fgraph.rb;h=011dd8625720dd601cd4868257ae7224273fb133;hb=32518a2c5089dbd3b9f74aad780ded127e3040ea;hp=e08a1ad8544d12aec4cacf3a095ca5e1e5df6aea;hpb=5d0d968af54bf21b892c25074a9ca452604bb210;p=graph.njae.git

diff --git a/lib/graph.njae/graph.rb b/lib/graph.njae/graph.rb
index e08a1ad..011dd86 100644
--- a/lib/graph.njae/graph.rb
+++ b/lib/graph.njae/graph.rb
@@ -7,8 +7,8 @@ module GraphNjae
   # A container for all the parts of a graph.  The graph can have arbitrary attributes,
   # treated as method names.
   class Graph < OpenStruct
-    def initialize
-      super
+    def initialize(values = {})
+      super(values)
       self.edges = Array.new
       self.vertices = Array.new
       self
@@ -23,5 +23,79 @@ module GraphNjae
       end
       self
     end
-  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 product graph.
+    def product(other)
+      product_graph = Graph.new
+      self.vertices.each do |v1|
+        other.vertices.each do |v2|
+          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]}
+          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]}
+          product_graph.connect source, destination
+        end
+      end
+      product_graph
+    end
+    
+    
+    def initial_similarity
+      self.vertices.each do |v|
+        if block_given?
+          v.initial_similarity = yield v
+        else
+          v.initial_similarity = 1.0
+        end
+        v.similarity = v.initial_similarity
+      end
+    end
+    
+    # Performs similarity flooding on a graph
+    # Assumes that the initial similarity has already been calculated
+    def similarity_flood(opts = {})
+      max_iterations = opts[:iterations] || 100
+      max_residual = opts[:max_residual] || 0.001
+      iteration = 1
+      residual = max_residual + 1
+      while residual > max_residual and iteration <= max_iterations
+        self.vertices.each do |v|
+          v.last_similarity = v.similarity
+        end
+        self.vertices.each do |v|
+           n = v.neighbours.length
+           v.neighbours.each do |neighbour|
+             neighbour.similarity += v.last_similarity / n
+           end
+        end
+        max_similarity = vertices.max {|v, w| v.similarity <=> w.similarity}.similarity
+        self.vertices.each do |v|
+          v.similarity = v.similarity / max_similarity
+        end
+        residual = Math.sqrt(self.vertices.reduce(0) {|a, v| a += (v.similarity - v.last_similarity) ** 2})
+        iteration += 1
+      end
+      
+    end
+    
+  end # class
 end