mutation: pass mutation probability to the mutater (#32)

examplegnetic_test.go

@@ -35,15 +35,20 @@ func (i *HIndividual) SetFitness(newFitness float64) {
 type HMutater struct {
 }
 
-func (m HMutater) Mutate(indiv evoli.Individual) (evoli.Individual, error) {
-	x := rand.Float64()*20 - 10
-	y := rand.Float64()*20 - 10
-	vx := rand.Float64()*20 - 10
-	vy := rand.Float64()*20 - 10
-	return &HIndividual{
-		x: []float64{x, y},
-		v: []float64{vx, vy},
-	}, nil
+func (m HMutater) Mutate(indiv evoli.Individual, p float64) (evoli.Individual, error) {
+	if rand.Float64() <= p {
+		x := rand.Float64()*20 - 10
+		y := rand.Float64()*20 - 10
+		vx := rand.Float64()*20 - 10
+		vy := rand.Float64()*20 - 10
+		return &HIndividual{
+			x: []float64{x, y},
+			v: []float64{vx, vy},
+		}, nil
+	} else {
+		return indiv, nil
+	}
+
 }
 
 type HCrosser struct {

genetic.go

@@ -137,15 +137,13 @@ func (g *genetic) mutations(pop Population) (Population, error) {
 		wg.Add(1)
 		go func(i int) {
 			defer wg.Done()
-			if rand.Float64() <= g.MutationProbability {
-				indiv := pop.Get(i)
-				mutant, err := g.mutater.Mutate(indiv)
-				if err != nil {
-					bubbledErr = err
-					return
-				}
-				pop.Replace(i, mutant)
+			indiv := pop.Get(i)
+			mutant, err := g.mutater.Mutate(indiv, g.MutationProbability)
+			if err != nil {
+				bubbledErr = err
+				return
 			}
+			pop.Replace(i, mutant)
 		}(i)
 	}
 	wg.Wait()

mock_test.go

@@ -22,7 +22,7 @@ func (e evaluaterMock) Evaluate(individual Individual) (Fitness float64, err err
 type mutaterMock struct {
 }
 
-func (m mutaterMock) Mutate(individual Individual) (Individual, error) {
+func (m mutaterMock) Mutate(individual Individual, p float64) (Individual, error) {
 	return individual, nil
 }
 

mutater.go

@@ -2,5 +2,5 @@ package evoli
 
 // Mutater randomly modify a individual. This operator maintain diversity in a population.
 type Mutater interface {
-	Mutate(Individual) (Individual, error)
+	Mutate(indiv Individual, p float64) (Individual, error)
 }