Class: Fdgd

Inherits:
Object
  • Object
show all
Defined in:
lib/rtl/fdgd.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(graph = nil) ⇒ Fdgd

Returns a new instance of Fdgd.



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# File 'lib/rtl/fdgd.rb', line 10

def initialize graph=nil
  puts "FDGD: force-directed graph drawer"
  @graph=graph
  @l0=80
  @c1=30
  @epsilon=10
  @damping=0.92
  @timestep=0.1
  @stop=false
end

Instance Attribute Details

#graph ⇒ Object

Returns the value of attribute graph.



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# File 'lib/rtl/fdgd.rb', line 7

def graph
  @graph
end

#stop ⇒ Object

Returns the value of attribute stop.



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# File 'lib/rtl/fdgd.rb', line 8

def stop
  @stop
end

Instance Method Details

#angle(a, b) ⇒ Object 



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# File 'lib/rtl/fdgd.rb', line 25

def angle a,b
  if dist(a,b)!=0
    if b.x > a.x
      angle = Math.asin((b.y-a.y)/dist(a,b))
    else
      angle = Math::PI - Math.asin((b.y-a.y)/dist(a,b))
    end
  else
    angle =0
  end
  return angle
end

#coulomb_repulsion(a, b) ⇒ Object 



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# File 'lib/rtl/fdgd.rb', line 38

def coulomb_repulsion a,b
  angle = angle(a,b)
  dab = dist(a,b)
  c= -0.2*(a.radius*b.radius)/Math.sqrt(dab)
  [c*Math.cos(angle),c*Math.sin(angle)]
end

#dist(a, b) ⇒ Object 



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# File 'lib/rtl/fdgd.rb', line 21

def dist a,b
  Math.sqrt((a.x - b.x)**2 + (a.y - b.y)**2)
end

#hooke_attraction(a, b) ⇒ Object

,c1=10#,l0=40



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# File 'lib/rtl/fdgd.rb', line 49

def hooke_attraction a,b #,c1=10#,l0=40
  angle = angle(a,b)
  dab = dist(a,b)
  c = @c1*Math.log((dab-@l0).abs)*sign_minus(dab,@l0)
  [c*Math.cos(angle),c*Math.sin(angle)]
end

#run(iter = 2) ⇒ Object 



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# File 'lib/rtl/fdgd.rb', line 56

def run iter=2
  if @graph
    Thread.new do
      step = 0
      total_kinetic_energy=1000
      next_pos={}
      next_speed={}
      until total_kinetic_energy < @epsilon or step==iter do

        step+=1
        total_kinetic_energy = 0

        for node in graph.nodes
          net_force = Vector.new(0, 0)

          for other in graph.nodes-[node]
            rep = coulomb_repulsion( node, other)
            net_force += rep
          end

          for edge in graph.edges.select{|e| e.source==node or e.sink==node}
            other = edge.sink==node ? edge.source : edge.sink
            attr = hooke_attraction(node, other) #, c1=30,@l0)
            net_force += attr
          end

          # without damping, it moves forever
          speed = (node.speed + net_force.scale(@timestep)).scale(@damping)
          next_pos[node.id]   = node.pos + speed.scale(@timestep)
          next_speed[node.id] = speed
          total_kinetic_energy += node.radius * speed.squared
        end

        #puts total_kinetic_energy
        yield if block_given?
        #update nodes position
        for node in graph.nodes
          unless node.fixed.x
            node.pos.x = next_pos[node.id].x
            node.speed.x = next_speed[node.id].x
          end
          unless node.fixed.y
            node.pos.y = next_pos[node.id].y
            node.speed.y = next_speed[node.id].y
          end
        end
        break if @stop
      end
      puts "algorithm end"
      puts "reached epsilon" if total_kinetic_energy < @epsilon
      puts "reached max iterations" if step==iter
    end #thread
  end
end

#sign_minus(a, b) ⇒ Object 



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# File 'lib/rtl/fdgd.rb', line 45

def sign_minus(a,b)
  a>b ? 1 : -1
end