import random
### we'll use the 'mixin' style here.

class Elites :

    def ApplyElitism(self, pop, erate) :
        raise NotImplementedError


class DeterministicElites(Elites) :
    def ApplyElitism(self, pop, erate) :
        pop.sort()
        pop.reverse()
        return pop[0:int(erate*len(pop))]

class TournamentElites(Elites) :
    def ApplyElitism(self, pop, erate) :
        children = []
        for i in range(int(erate * len(pop))) :
            c1 = random.choice(pop)
            c2 = random.choice(pop)
            if c1 > c2 :
                children.append(c1)
            else :
                children.append(c2)
        return children


class RouletteElites(Elites) :
    def ApplyElitism(self, pop, erate) :

        total = sum([x.fitness for x in pop])
        children = []
        for j in range(int(erate * len(pop))) :
            rval = random.randint(0,total)
            i = 0
            counter = pop[0].fitness
            while counter < rval and i < len(pop) -1 :
                counter += pop[i].fitness
                i += 1
            children.append(pop[i])
        return children