sketch-a-day/s182/Population.pde

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// The Nature of Code
// Daniel Shiffman
// http://natureofcode.com
// Interactive Selection
// http://www.genarts.com/karl/papers/siggraph91.html
// A class to describe a population of faces
// this hasn't changed very much from example to example
class Population {
float mutationRate; // Mutation rate
Organism[] population; // array to hold the current population
ArrayList<Organism> matingPool; // ArrayList which we will use for our "mating pool"
int generations; // Number of generations
// Create the population
Population(float m, int num) {
mutationRate = m;
population = new Organism[num];
matingPool = new ArrayList<Organism>();
generations = 0;
//for (int i = 0; i < population.length; i++) {
// population[i] = new Organism(new DNA(), 50+i*88.5, 60);
//}
float s = width/5.2;
int i = 0;
for (int x = 0; x < 5; x++) {
for (int y = 0; y < 5; y++) {
population[i] = new Organism(new DNA(), s/1.75+x*s, s/1.75+y*s);
i++;
}
}
}
// Display all faces
void display() {
for (int i = 0; i < population.length; i++) {
population[i].display();
}
}
// Are we rolling over any of the faces?
void rollover(int mx, int my) {
for (int i = 0; i < population.length; i++) {
population[i].checkMouseOver(mx, my);
}
}
// Generate a mating pool
void selection() {
// Clear the ArrayList
matingPool.clear();
// Calculate total fitness of whole population
float maxFitness = getMaxFitness();
// Calculate fitness for each member of the population (scaled to value between 0 and 1)
// Based on fitness, each member will get added to the mating pool a certain number of times
// A higher fitness = more entries to mating pool = more likely to be picked as a parent
// A lower fitness = fewer entries to mating pool = less likely to be picked as a parent
for (int i = 0; i < population.length; i++) {
float fitnessNormal = map(population[i].getFitness(), 0, maxFitness, 0, 1);
int n = (int) (fitnessNormal * 100); // Arbitrary multiplier
for (int j = 0; j < n; j++) {
matingPool.add(population[i]);
}
}
}
// Making the next generation
void reproduction() {
// Refill the population with children from the mating pool
for (int i = 0; i < population.length; i++) {
// Sping the wheel of fortune to pick two parents
int m = int(random(matingPool.size()));
int d = int(random(matingPool.size()));
// Pick two parents
Organism mom = matingPool.get(m);
Organism dad = matingPool.get(d);
// Get their genes
DNA momgenes = mom.getDNA();
DNA dadgenes = dad.getDNA();
// Mate their genes
DNA child = momgenes.crossover(dadgenes);
// Mutate their genes
child.mutate(mutationRate);
// Fill the new population with the new child
population[i] = new Organism(child, population[i].x, population[i].y);
}
generations++;
}
int getGenerations() {
return generations;
}
// Find highest fintess for the population
float getMaxFitness() {
float record = 0;
for (int i = 0; i < population.length; i++) {
if (population[i].getFitness() > record) {
record = population[i].getFitness();
}
}
return record;
}
}