void crossover_function(population& p)
{
population new_population;
std::vector<int> cross_set;
std::vector<int>::iterator it;
float rd;
// choose which specimen will crossover
for(int i=0; i<population_size; i++)
{
rd = (randid()*1.0f) / (RAND_MAX*1.0f*population_size);
if(rd > p[i].adapt)
cross_set.push_back(i);
}
// we want even number of parents
if(cross_set.size() & 1)
cross_set.pop_back();
// more randomness
random_shuffle ( cross_set.begin(), cross_set.end(), p_randgenid );
it = cross_set.begin();
// crossover each pair from left to right
while( it != cross_set.end())
{
std::pair<permutation,permutation> desc;
crossover::type ctype;
if(cfg.compare_operators)
{
switch(randid() % xop_count)
{
case 0: ctype = crossover::type::OX; break;
case 1: ctype = crossover::type::CX; break;
case 2:
default: ctype = crossover::type::PMX; break;
}
desc = crossover::random_crossover(ctype, p[*it].perm, p[*(it+1)].perm);
}
else
{
desc = crossover::random_crossover(cfg.crossover_type, p[*it].perm, p[*(it+1)].perm);
}
specimen ch1, ch2;
ch1.perm = desc.first;
ch1.eval = evaluation(ch1.perm);
ch1.adapt = 0.0;
ch2.perm = desc.second;
ch2.eval = evaluation(ch2.perm);
ch2.adapt = 0.0;
if(cfg.compare_operators && ( ((p[*it].eval + p[*(it+1)].eval) / (ch1.eval + ch2.eval)) >= 1 ) )
{
switch(ctype)
{
case crossover::type::OX: ox_count++; break;
case crossover::type::CX: cx_count++; break;
case crossover::type::PMX:
default: pmx_count++; break;
}
}
it++; it++;
x_count++;
new_population.push_back(ch1);
new_population.push_back(ch2);
}
p.insert(p.end(), new_population.begin(), new_population.end());
}
