public static GAPopulation generate(GAPopulation p, int xrate, int mrate)
{
// Generate a new population from p, xrate percent of the induviduals
// of new population are generated by cross-over, mrate percent of them are
// generated by mutation, and others by reproduction.
if (xrate < 0 || xrate > 100 || mrate < 0 || mrate > 100 || xrate + mrate > 100)
{
Console.Error.WriteLine("error: xrate and/or mrate are not properly set");
}
GAIndividual[] newg = new GAIndividual[p.pop_size];
int newg_index = 0;
int xn = xrate * p.pop_size / 100; // xn: number of offsprings to be produced by xover
int mn = mrate * p.pop_size / 100; // mn: number of offsprings to be produced by mutation
// xover:
for (int i = 0; i < xn; i++)
{
// select two parents for cross-over:
// we want two distinct parents (i.e. p1 != p2)
int p1, p2;
do
{
p1 = p.tr_select();
p2 = p.tr_select();
}while (p1 == p2);
newg[newg_index++] = GAIndividual.xover1p(p.ind[p1], p.ind[p2]);
}
// mutation:
for (int i = 0; i < mn; i++)
{
newg[newg_index++] = p.ind[p.tr_select()].mutate();
}
// reproduction:
for (int i = newg_index; i < p.pop_size; i++)
{
newg[i] = p.ind[p.tr_select()];
}
return(new GAPopulation(newg));
}
