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chromosome.rb
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chromosome.rb
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class Chromosome
attr_reader :length, :genes, :fitness
def initialize(opts = {})
@length = opts.fetch :length, 8
@genes = opts.fetch :genes, []
end
# The `mutates` method tries to swap genes `count` when dices are within `chances`.
def mutate(count, chances)
count.times.each do
next unless rand(100) < chances
idx1 = rand @length
until (idx2 = rand(@length)) != idx1; end
@genes[idx1], @genes[idx2] = @genes[idx2], @genes[idx1]
end
end
# Determines to what level this chromosome is fit to survive.
# The higher the return value is, the less viable is the chromosome.
def fitness
@fitness ||= (
outter_bound, inner_bound = @length -2, @length - 1
(0..outter_bound).inject(0) do |e1, x1|
y1 = @genes[x1]
e1 + ((x1+1)..inner_bound).inject(0) do |e2, x2|
y2 = @genes[x2]
dx, dy = (x1 - x2).abs, (y1 - y2).abs
e2 + ((y1 == y2 || dx == dy) ? 1 : 0)
end
end
)
end
# Allow duplication of a chromosome for easing crossover. The fitness is not
# duplicated (cache-busting).
def dup
self.class.new(
length: @length,
genes: @genes.dup
)
end
# Creates a new Chromosome instance with random genes.
def self.new_random(length)
new length: length, genes: (0..(length-1)).to_a.shuffle
end
end