import numpy as np
import random

def select(individuals, sizepop):
    # 本函数对每一代种群中的染色体进行选择，以进行后面的交叉和变异
    # individuals input : 种群信息
    # sizepop input : 种群规模
    # opts input : 选择方法的选择
    # ret output : 经过选择后的种群
    # yuan=individuals;
    individuals['fitness'] = 1 / individuals.get('fitness')
    sumfitness = np.sum(individuals.get('fitness'))
    sumf = individuals.get('fitness') / sumfitness
    index = []
    for i in range(sizepop): # 转sizepop次轮盘
        pick = random.random()
        while pick == 0:
            pick = random.random()
        for j in range(sizepop):
            pick = pick - sumf[j]
            if pick < 0:
                index.append(j)
                break # 寻找落入的区间，此次转轮盘选中了染色体i，注意：在转sizepop次轮盘的过程中，有可能会重复选择某些染色体
    # index=unique(index);
    # individuals=yuan;
    individuals['chrom'] = individuals.get('chrom')[index, :]
    individuals['fitness'] = individuals.get('fitness')[index]
    ret = individuals
    return ret