// Evolve implements the inner loop of the evolutionary algorithm.
// The population calls the Evolve method of each genome, in parallel. Then,
// each receiver returns a value to replace it in the next generation.
func Evolve(current evo.Genome, matingPool []evo.Genome) evo.Genome {
// Selection:
// Select each parent using a simple random binary tournament
mom := sel.BinaryTournament(matingPool...).(*tsp)
dad := sel.BinaryTournament(matingPool...).(*tsp)
// Crossover:
// Edge recombination
child := &tsp{gene: pool.Get().([]int)}
perm.EdgeX(child.gene, mom.gene, dad.gene)
// Mutation:
// There is an n% chance for the gene to have n random swaps
// and an n% chance to undergo n steps of a greedy 2-opt hillclimber
for rand.Float64() < 0.1 {
perm.RandSwap(child.gene)
}
for rand.Float64() < 0.1 {
child.TwoOpt()
}
// Replacement:
// Only replace if the child is better or equal
if current.Fitness() > child.Fitness() {
return current
}
return child
}
func TestEdgeX(t *testing.T) {
mom := rand.Perm(8)
dad := rand.Perm(8)
child := make([]int, 8)
perm.EdgeX(child, mom, dad)
validate(t, child)
}