{key, value(数値)}の辞書でルーレット選択

Roulette

for i in self.pronlist.values():
    totalweight += i
r = random.randint(1, totalweight)

for k,v in sorted(self.pronlist.items(), key=lambda x:x[1], reverse=True):
    if r <= v:
        pron = k
        break
    else:
        r -= v
return pron