Class: MHL::QuantumParticle

Inherits:
GenericParticle show all
Defined in:
lib/mhl/quantum_particle.rb

Instance Attribute Summary collapse

Attributes inherited from GenericParticle

#attractor

Instance Method Summary collapse

Methods inherited from GenericParticle

#evaluate, #initialize

Constructor Details

This class inherits a constructor from MHL::GenericParticle

Instance Attribute Details

#position ⇒ Object (readonly)

Returns the value of attribute position.



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# File 'lib/mhl/quantum_particle.rb', line 8

def position
  @position
end

Instance Method Details

#move(alpha, mean_best, swarm_attractor) ⇒ Object

move particle using QPSO - Type II algorithm



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# File 'lib/mhl/quantum_particle.rb', line 11

def move(alpha, mean_best, swarm_attractor)
  raise 'Particle attractor is nil!' if @attractor.nil?

  dimension = @position.size

  # phi represents the \phi_{i,n} parameter in [SUN11], formula 4.83
  phi = Array.new(dimension) { SecureRandom.random_number }

  # p_i represents the p_{i,n} parameter in [SUN11], formulae 4.82 and 4.83
  p_i = phi.zip(@attractor[:position], swarm_attractor[:position]).map do |phi_j,p_j,g_j|
    phi_j * p_j + (1.0 - phi_j) * g_j
  end

  # delta represents the displacement for the current position.
  # See [SUN11], formula 4.82
  delta = @position.zip(mean_best).map do |x_n,c_n| 
    # \alpha * | X_{i,n} - C_n | * log(\frac{1}{u_{i,n+1}})
    alpha * (x_n - c_n).abs * Math.log(1.0 / SecureRandom.random_number)
  end

  # update position
  if SecureRandom.random_number < 0.5
    @position = p_i.zip(delta).map {|p_in,delta_n| p_in + delta_n }
  else
    @position = p_i.zip(delta).map {|p_in,delta_n| p_in - delta_n }
  end

  @position
end

#remain_within(constraints) ⇒ Object

implement confinement à la SPSO 2011. for more information, see equations 3.14 of [CLERC12].



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# File 'lib/mhl/quantum_particle.rb', line 43

def remain_within(constraints)
  @position = @position.map.with_index do |x_j,j|
    d_max = constraints[:max][j]
    d_min = constraints[:min][j]
    if x_j > d_max
      # puts "resetting #{j}-th position component #{x_j} to #{d_max}"
      x_j = d_max
    elsif x_j < d_min
      # puts "resetting #{j}-th position component #{x_j} to #{d_min}"
      x_j = d_min
    end
    x_j
  end
end