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 15

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 8

def infinity
  @infinity
end

#links ⇒ Object

Returns the value of attribute links.



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# File 'lib/rgraph/graph.rb', line 8

def links
  @links
end

#nodes ⇒ Object

Returns the value of attribute nodes.



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# File 'lib/rgraph/graph.rb', line 8

def nodes
  @nodes
end

Class Method Details

.new_from_string(string) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 10

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 51

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

#between(i, args = {}) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 133

def between(i, args = {})
  giant = args[:giant] || false
  shortest_paths(multiples: true, giant: giant)

  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 142

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

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

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

  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.values.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.values[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 55

def cumulative_degree
  out = (0..(degrees.max - 1)).map { |i| degrees.select{|degree| degree > i}.count }
  out.map{|a| a / out.max.to_f}
end

#degrees ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 47

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

#diameter ⇒ Object 



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

def diameter
  distances unless @distance

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

#distances ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 72

def distances
  @path = matrix(@nodes.size, [nil])
  @distance = idistance.fw!(@path)
end

#each_link(&block) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 43

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

#each_node(&block) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 39

def each_node(&block)
  @nodes.each_value(&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

#giant_component ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 221

def giant_component
  components unless @components

  @giant_component = []
  @components.each do |c|
    @giant_component = c if c.size > @giant_component.size
  end

  @giant_component
end

#idistance ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 60

def idistance
  dist = matrix(@nodes.size, 0)

  @nodes.values.each_with_index do |n1, i|
    @nodes.values.each_with_index do |n2, j|
      next if i == j
      dist[i][j] = n1.has_neighbour?(n2) ? link_between(n1, n2)[:weight].to_i : @infinity
    end
  end
  dist
end

#mdistance ⇒ Object 



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

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)

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

#shortest_path(i, j, multiples = false, giant = false) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 104

def shortest_path(i, j, multiples = false, giant = false)
  nodes = giant ? @giant_component : @nodes.values

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

  path = @path[i][j].count == 1 || multiples ? @path[i][j] : [@path[i][j].first]
  out = []

  path.each do |k|

    case k
    when @infinity
      out << []
    when nil
      out << [i,j]
    else
      i_k = shortest_path(i, k)
      k_j = shortest_path(k, j)

      i_k.each do |ik|
        k_j.each do |kj|
          out << ik[0..-2] + [k] + kj[1..-1]
        end
      end
    end
  end
  out
end

#shortest_paths(args = {}) ⇒ Object 



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# File 'lib/rgraph/graph.rb', line 84

def shortest_paths(args = {})
  multiples = args[:multiples] || false
  giant = args[:giant] || false

  @shortest_paths = []

  distances
  giant_component

  nodes = giant ? @giant_component : @nodes.values

  0.upto(nodes.size - 1).each do |i|
    (i + 1).upto(nodes.size - 1).each do |j|
      @shortest_paths += shortest_path(i, j, multiples, giant)
    end
  end

  @shortest_paths
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