Class: Graph

Inherits:
Object
  • Object
show all
Defined in:
lib/rgraph/graph.rb

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(csv) ⇒ Graph

Returns a new instance of Graph.



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# File 'lib/rgraph/graph.rb', line 14

def initialize(csv)
  @nodes = []
  @links = []
  @distance = nil
  @infinity = 100_000

  csv = CSV.new(File.open(csv), headers: true) if csv.is_a?(String)

  csv.each do |row|
    #last because CSV#delete returns [column,value]
    source_id = row.delete('source').last
    target_id = row.delete('target').last
    type = row.delete('type').last || 'undirected'
    weight = row.delete('weight').last || 1

    source = get_node_by_id(source_id) || Node.new(id: source_id)
    target = get_node_by_id(target_id) || Node.new(id: target_id)

    maybe_add_to_nodes(source, target)

    @links << Link.new(source: source, target: target, weight: weight, type: type)
  end
end

Instance Attribute Details

#infinity ⇒ Object

Returns the value of attribute infinity.



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# File 'lib/rgraph/graph.rb', line 7

def infinity
  @infinity
end

#links ⇒ Object

Returns the value of attribute links.



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# File 'lib/rgraph/graph.rb', line 7

def links
  @links
end

#nodes ⇒ Object

Returns the value of attribute nodes.



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# File 'lib/rgraph/graph.rb', line 7

def nodes
  @nodes
end

Class Method Details

.new_from_string(string) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 9

def self.new_from_string(string)
  csv = CSV.new(string, headers: true)
  new(csv)
end

Instance Method Details

#average_degree ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 50

def average_degree
  degrees.inject(:+) / @nodes.size.to_f
end

#between(i) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 135

def between(i)
  shortest_paths unless @shortest_paths

  n = @shortest_paths.select{|c| c[1..-2].include?(i)}.size.to_f
  m = @shortest_paths.size.to_f
  n / m
end

#betweenness(args = {}) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 143

def betweenness(args = {})
  cumulative = args[:cumulative] || false

  #If we ask cumulative, normalized must be true
  normalized = args[:normalized] || cumulative || false

  bts = 0.upto(@nodes.size - 1).map { |i| between(i) }

  if normalized
    max = bts.max
    min = bts.min

    bts.map!{|bt| (bt - min) / (max - min)}
  end

  if cumulative
    bts.uniq.sort.map{ |bt1| [bts.select{|bt2| bt2 >= bt1}.count, bt1] }
  else
    bts
  end
end

#closeness ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 177

def closeness
  farness.map{|f| 1.0 / f }
end

#clustering ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 189

def clustering
  nodes.map{ |node| single_clustering(node) }.inject(:+) / nodes.size.to_f
end

#components ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 204

def components
  distances unless @distance

  @components = []

  @distance.each do |d|
    same = []
    d.each_with_index { |dist, i| same << @nodes[i] if dist != @infinity}

    #its a new component
    if @components.select{ |c| c.include?(same.first) }.size == 0
      @components << same
    end
  end
  @components
end

#cumulative_degree ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 54

def cumulative_degree
  cached_degrees = degrees
  out = []

  0.upto(degrees.max - 1) do |i|
    out[i] = cached_degrees.select{|degree| degree > i}.count
  end
  out.map{|a| a / out.max.to_f}
end

#degrees ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 46

def degrees
  @nodes.map{|node| node.degree}
end

#diameter ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 165

def diameter
  distances unless @distance

  (distances.flatten - [@infinity]).max
end

#distances ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 77

def distances
  @path = Array.new(@nodes.size) { Array.new(@nodes.size, nil) }

  @distance = idistance
  @distance.each_index do |k|
    @distance.each_index do |i|
      @distance.each_index do |j|
        new_dist = @distance[i][k] + @distance[k][j]
        if @distance[i][j] > new_dist
          @distance[i][j] = new_dist
          @path[i][j] = k
        end
      end
    end
  end
  @distance
end

#each_link(&block) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 42

def each_link(&block)
  @links.each(&block)
end

#each_node(&block) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 38

def each_node(&block)
  @nodes.each(&block)
end

#farness ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 171

def farness
  distances unless @distance

  @distance.map{ |line| line.select{|l| l != @infinity }.inject(:+) }
end

#idistance ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 64

def idistance
  dist = Array.new(@nodes.size) { Array.new(@nodes.size, 0) }

  @nodes.sort{|a,b| a.id <=> b.id}.each_with_index do |n1, i|
    @nodes.sort{|a,b| a.id <=> b.id}.each_with_index do |n2, j|
      if i != j
        dist[i][j] = n1.neighbours.include?(n2) ? @links.select{ |link| (link.source == n1 || link.source == n2) && (link.target == n1 || link.target == n2) }.first.weight.to_i : @infinity
        end
    end
  end
  dist
end

#mdistance ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 95

def mdistance
  distances unless @distance

  fdistance = @distance.flatten.select{|d| d != @infinity}
  fdistance.inject(:+) / fdistance.count.to_f
end

#page_rank(d = 0.85, e = 0.01) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 193

def page_rank(d = 0.85, e = 0.01)
  n = @nodes.count

  #Initial values
  @page_rank = Array.new(n, 1 / n.to_f)

  while true
    return @page_rank if @page_rank.inject(:+) - step_page_rank(d, e).inject(:+) < e
  end
end

#shortest_path(i, j) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 118

def shortest_path(i, j)

  return [] if @distance[i][j] == @infinity

  k = @path[i][j]

  case k
  when @infinity
    []
  when nil
    [i,j]
  else
    #We need to do this or k will appear three times
    shortest_path(i, k)[0..-2] + [k] + shortest_path(k, j)[1..-1]
  end
end

#shortest_paths ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 102

def shortest_paths
  tmp = []

  distances unless @my_shortest_paths

  0.upto(@nodes.size - 1).each do |i|
    i.upto(@nodes.size - 1).each do |j|
      next if i == j
      sp = shortest_path(i, j)
      tmp << sp unless sp.empty?
    end
  end

  @shortest_paths = tmp
end

#single_clustering(node) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 181

def single_clustering(node)
  possible = possible_connections(node)
  return 0 if possible == 0

  existent = node.neighbours.combination(2).select{ |t| t[0].neighbours.include?(t[1]) }.count
  existent / possible.to_f
end