class MHL::ChargedSwarm
Constants
- DEFAULT_CHARGED_TO_NEUTRAL_RATIO
default composition is half charged, i.e., QPSO, and half neutral, i.e., traditional PSO (with inertia), swarms
Public Class Methods
new(size:, initial_positions:, initial_velocities:, charged_to_neutral_ratio: nil, alpha: nil, c1: nil, c2: nil, chi: nil, constraints: nil, logger: nil)
click to toggle source
# File lib/mhl/charged_swarm.rb, line 11 def initialize(size:, initial_positions:, initial_velocities:, charged_to_neutral_ratio: nil, alpha: nil, c1: nil, c2: nil, chi: nil, constraints: nil, logger: nil) @size = size # retrieve ratio between charged (QPSO) and neutral (constrained PSO) particles ratio = (charged_to_neutral_ratio || DEFAULT_CHARGED_TO_NEUTRAL_RATIO).to_f unless ratio > 0.0 raise ArgumentError, 'Parameter :charged_to_neutral_ratio should be a real greater than zero!' end num_charged_particles = (@size * ratio).round @num_neutral_particles = @size - num_charged_particles # the particles are ordered, with neutral (PSO w/ inertia) particles # first and charged (QPSO) particles later @particles = Array.new(@size) do |index| if index < @num_neutral_particles Particle.new(initial_positions[index], initial_velocities[index]) else QuantumParticle.new(initial_positions[index]) end end # find problem dimension @dimension = initial_positions[0].size @iteration = 1 # define procedure to get dynamic value for alpha @get_alpha = if alpha and alpha.respond_to? :call alpha else ->(it) { (alpha || DEFAULT_ALPHA).to_f } end # get values for parameters C1 and C2 @c1 = (c1 || DEFAULT_C1).to_f @c2 = (c2 || DEFAULT_C2).to_f # define procedure to get dynamic value for chi @get_chi = if chi and chi.respond_to? :call chi else ->(it) { (chi || DEFAULT_CHI).to_f } end @constraints = constraints @logger = logger if @constraints and @logger @logger.info "ChargedSwarm called w/ constraints: #{@constraints}" end end
Public Instance Methods
mutate()
click to toggle source
# File lib/mhl/charged_swarm.rb, line 66 def mutate # get alpha parameter alpha = @get_alpha.call(@iteration) # get chi parameter chi = @get_chi.call(@iteration) # this calculates the C_n parameter (the centroid of the set of all the # particle attractors) as defined in equations 4.81 and 4.82 of [SUN11]. # # Note: we consider ALL the particles here, not just the charged (QPSO) # ones. As a result, the neutral particles influence the behavior of the # charged ones not only by defining the swarm attractor, but also the # centroid. attractors = @particles.map {|p| p.attractor[:position] } c_n = 0.upto(@dimension-1).map do |j| attractors.inject(0.0) {|s,attr| s += attr[j] } / @size.to_f end @particles.each_with_index do |p,i| # remember: the particles are kept in a PSO-first and QPSO-last order if i < @num_neutral_particles p.move(chi, @c1, @c2, @swarm_attractor) else p.move(alpha, c_n, @swarm_attractor) end if @constraints p.remain_within(@constraints) end end @iteration += 1 end