Module: GRATR::AdjacencyGraph

Includes:
Graph
Included in:
Digraph, UndirectedGraph
Defined in:
lib/gratr/adjacency_graph.rb

Overview

This provides the basic routines needed to implement the Digraph, UndirectedGraph, PseudoGraph, DirectedPseudoGraph, MultiGraph and DirectedPseudoGraph class.

Defined Under Namespace

Classes: ArrayWithAdd

Class Method Summary collapse

Instance Method Summary collapse

Methods included from Graph

#dotty, #to_dot, #to_dot_graph, #write_to_graphic_file

Class Method Details

.included(cl) ⇒ Object 



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# File 'lib/gratr/adjacency_graph.rb', line 199

def self.included(cl)
  # Shortcut for creating a Graph
  #
  #  Example: GRATR::Digraph[1,2, 2,3, 2,4, 4,5].edges.to_a.to_s =>
  #    "(1-2)(2-3)(2-4)(4-5)"
  # 
  # Or as a Hash for specifying lables
  # GRATR::Digraph[ [:a,:b] => 3, [:b,:c] => 4 ]  (Note: Do not use for Multi or Pseudo graphs)
  def cl.[] (*a)
    result = new
    if a.size == 1 and a[0].kind_of? Hash
      # Convert to edge class
      a[0].each do |k,v|
        if result.edge_class.include? GRATR::ArcNumber
          result.add_edge!(result.edge_class[k[0],k[1],nil,v])
        else
         result.add_edge!(result.edge_class[k[0],k[1],v])
        end 
      end
    elsif a[0].kind_of? GRATR::Arc
      a.each{|e| result.add_edge!(e); result[e] = e.label}
    elsif a.size % 2 == 0    
      0.step(a.size-1, 2) {|i| result.add_edge!(a[i], a[i+1])}
    else
      raise ArgumentError
    end
    result
  end
end

Instance Method Details

#add_edge!(u, v = nil, l = nil, n = nil) ⇒ Object

Adds an edge to the graph Can be called in two basic ways, label is optional

* add_edge!(Arc[source,target], "Label")
* add_edge!(source,target, "Label")



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# File 'lib/gratr/adjacency_graph.rb', line 109

def add_edge!(u, v=nil, l=nil, n=nil)
  n = u.number if u.class.include? ArcNumber and n.nil?
  u, v, l = u.source, u.target, u.label if u.kind_of? GRATR::Arc
  return self if not @allow_loops and u == v
  n = (@next_edge_number+=1) unless n if @parallel_edges
  add_vertex!(u); add_vertex!(v)        
  @vertex_dict[u].add(v)
  (@edge_number[u] ||= @edgelist_class.new).add(n) if @parallel_edges
  unless directed?
    @vertex_dict[v].add(u)
    (@edge_number[v] ||= @edgelist_class.new).add(n) if @parallel_edges
  end        
  self[n ? edge_class[u,v,n] : edge_class[u,v]] = l if l
  self
end

#add_vertex!(vertex, label = nil) ⇒ Object

Adds a vertex to the graph with an optional label



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# File 'lib/gratr/adjacency_graph.rb', line 99

def add_vertex!(vertex, label=nil)
  @vertex_dict[vertex] ||= @edgelist_class.new
  self[vertex] = label if label
  self
end

#adjacent(x, options = {}) ⇒ Object 



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# File 'lib/gratr/adjacency_graph.rb', line 180

def adjacent(x, options={})
  options[:direction] ||= :out
  if !x.kind_of?(GRATR::Arc) and (options[:direction] == :out || !directed?)
    if options[:type] == :edges
      i = -1
      @parallel_edges ?
        @vertex_dict[x].map {|v| e=edge_class[x,v,@edge_number[x][i+=1]]; e.label = self[e]; e} :
        @vertex_dict[x].map {|v| e=edge_class[x,v];  e.label = self[e]; e}
    else
      @vertex_dict[x].to_a
    end
  else
    graph_adjacent(x,options)
  end
end

#edge?(u, v = nil) ⇒ Boolean

Returns true if [u,v] or u is an Arc An O(1) implementation

Returns:

  • (Boolean) 


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# File 'lib/gratr/adjacency_graph.rb', line 93

def edge?(u, v=nil)
  u, v = u.source, u.target if u.kind_of? GRATR::Arc
  vertex?(u) and @vertex_dict[u].include?(v)
end

#edges ⇒ Object

Returns an array of edges, most likely of class Arc or Edge depending upon the type of graph



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# File 'lib/gratr/adjacency_graph.rb', line 164

def edges
  @vertex_dict.keys.inject(Set.new) do |a,v|
    if @parallel_edges and @edge_number[v]
      @vertex_dict[v].zip(@edge_number[v]).each do |w|
        s,t,n = v,w[0],w[1]
        a.add( edge_class[ s,t,n, edge_label(s,t,n) ] )
      end
    else
      @vertex_dict[v].each do |w|
        a.add(edge_class[v,w,edge_label(v,w)])
      end
    end; a
  end.to_a
end

#graph_adjacent ⇒ Object 



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# File 'lib/gratr/adjacency_graph.rb', line 179

alias graph_adjacent adjacent

#initialize(*params) ⇒ Object

Initialization parameters can include an Array of edges to add, Graphs to copy (will merge if multiple) :parallel_edges denotes that duplicate edges are allowed :loops denotes that loops are allowed

Raises:

  • (ArgumentError) 


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# File 'lib/gratr/adjacency_graph.rb', line 50

def initialize(*params)
  @vertex_dict     = Hash.new    
  raise ArgumentError if params.any? do |p| 
    !(p.kind_of? GRATR::Graph or 
      p.kind_of? Array or 
      p == :parallel_edges or
      p == :loops)
  end
  clear_all_labels

  # Basic configuration of adjacency
  @allow_loops    = params.any? {|p| p == :loops}
  @parallel_edges = params.any? {|p| p == :parallel_edges}
  @edgelist_class = @parallel_edges ? ArrayWithAdd : Set
  if @parallel_edges
    @edge_number      = Hash.new
    @next_edge_number = 0 
  end

  # Copy any given graph into this graph
  params.select {|p| p.kind_of? GRATR::Graph}.each do |g|
    g.edges.each do |e| 
      add_edge!(e)
      edge_label_set(e, edge_label(e)) if edge_label(e)
    end
    g.vertices.each do |v|
      vertex_label_set(v, vertex_label(v)) if vertex_label(v)
    end  
  end

  # Add all array edges specified
  params.select {|p| p.kind_of? Array}.each do |a|
    0.step(a.size-1, 2) {|i| add_edge!(a[i], a[i+1])}
  end

end

#remove_edge!(u, v = nil) ⇒ Object

Removes an edge from the graph, can be called with source and target or with and object of GRATR::Arc derivation

Raises:

  • (ArgumentError) 


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# File 'lib/gratr/adjacency_graph.rb', line 140

def remove_edge!(u, v=nil)
  unless u.kind_of? GRATR::Arc
    raise ArgumentError if @parallel_edges
    u = edge_class[u,v]
  end
  raise ArgumentError if @parallel_edges and (u.number || 0) == 0
  return self unless @vertex_dict[u.source] # It doesn't exist
  delete_label(u) # Get rid of label
  if @parallel_edges
    index = @edge_number[u.source].index(u.number)
    raise NoArcError unless index
    @vertex_dict[u.source].delete_at(index)
    @edge_number[u.source].delete_at(index) 
  else
    @vertex_dict[u.source].delete(u.target) 
  end
  self
end

#remove_vertex!(v) ⇒ Object

Removes a given vertex from the graph



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# File 'lib/gratr/adjacency_graph.rb', line 126

def remove_vertex!(v)
# FIXME This is broken for multi graphs 
  @vertex_dict.delete(v)
  @vertex_dict.each_value { |adjList| adjList.delete(v) }
  @vertex_dict.keys.each  do |u| 
    delete_label(edge_class[u,v]) 
    delete_label(edge_class[v,u])
  end
  delete_label(v) 
  self
end

#vertex?(v) ⇒ Boolean

Returns true if v is a vertex of this Graph An O(1) implementation of vertex?

Returns:

  • (Boolean) 


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# File 'lib/gratr/adjacency_graph.rb', line 89

def vertex?(v) @vertex_dict.has_key?(v); end

#vertices ⇒ Object

Returns an array of vertices that the graph has



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# File 'lib/gratr/adjacency_graph.rb', line 160

def vertices() @vertex_dict.keys; end