一个简单的遗传算法实例源码

204 阅读1分钟

研究论文时,实现了一个简单的遗传算法原型,写在这里供大家参考指正

运行结果如下:

1.png 2.png

3.png

4.png

#代码如下

##main.py:

# 尝试用遗传算法来计算一个函数的最大值
import random

import numpy

from bitopt import Bit
from bitopt import cross
import numpy as np
from matplotlib import pyplot as plt


def generate_first(in_chromosomeNum, space_num):
    ret_array = []
    for i in range(in_chromosomeNum):
        ret_array.append(random.randint(1, space_num))
    return ret_array


# 轮盘赌函数
def Roulette(in_adaptablity):
    sum_adapt = sum(in_adaptablity)
    selecter = random.random()  # 生成 0 - 1的随机值
    Probability_Total = 0
    for index, item in enumerate(in_adaptablity):
        # 这里的in_adaptablity 数组为浮点数数组
        Probability_Total = Probability_Total + item / sum_adapt
        if Probability_Total > selecter:
            return index


def select(in_chromosomeMatrix, in_adaptablity):
    # 根据轮盘赌原则选择两个个体,以进行繁殖
    a_index = Roulette(in_adaptablity)
    b_index = Roulette(in_adaptablity)
    if in_adaptablity[a_index] <= in_adaptablity[b_index]:
        return in_chromosomeMatrix[b_index]
    else:
        return in_chromosomeMatrix[a_index]


def new_individual(in_a: int, in_b: int):
    # 这里进行交叉变异操作,以产生子个体
    a_bit = Bit(in_a)
    b_bit = Bit(in_b)
    max_index = max(a_bit.ret_len(), b_bit.ret_len()) - 1
    r_p = random.random()
    if r_p < 0.90:  # 0.9交叉概率
        r_index = random.randint(0, max_index)  # 单点交叉的位点
        cross(a_bit, b_bit, r_index, max_index)  # 二进制交叉
    r_p = random.random()
    if r_p < 0.01:  # 1/100概率变异
        r_index = random.randint(0, max_index)  # 单点交叉的位点
        a_bit.reverse(r_index)

    return a_bit.ret_num(), b_bit.ret_num()


def generate_next(in_chromosomeMatrix, in_adaptablity,space_num):
    new_chromosomeMatrix = []
    while len(new_chromosomeMatrix) < len(in_chromosomeMatrix):  # 直到繁殖的数量达到预先给定的种群大小
        a = select(in_chromosomeMatrix, in_adaptablity)  # 选择出两个优良个体
        b = select(in_chromosomeMatrix, in_adaptablity)  # 选择出两个优良个体
        new_a, new_b = new_individual(a, b)
        if 0 <= new_a <= space_num and 0 <= new_b <= space_num: # 二进制交叉后可能会产生不属于考虑范围的值,应该剔除
            new_chromosomeMatrix.append(new_a)
            new_chromosomeMatrix.append(new_b)
   
    # print("generate next generation.")
    # print(new_chromosomeMatrix)
    return new_chromosomeMatrix


def calAdaptability(in_chromosomeMatrix, target_func, start, end, space_num):
    # 使用函数值的高低来表示可靠度 应当全部是正值

    my_map = lambda x: float(end - start) / space_num * x
    myfunc = target_func
    ret_array = []
    for i in range(len(in_chromosomeMatrix)):
        ret_array.append(myfunc(my_map(in_chromosomeMatrix[i])))
        # print(ret_array[i])
    return ret_array


def ga_algo(iterNum, chromosomeNum, target_func, start, end, space_num):
    chromosomeMatrix = generate_first(chromosomeNum, space_num)
    adaptabilityMatrix = []
    # fig, ax = plt.subplots()
    # plt.show()
    plt.ion()  # 交互模式
    for i in range(iterNum):
        # print("{}===>>", i)
        adaptabilityMatrix = calAdaptability(chromosomeMatrix, target_func, start, end, space_num)
        # print(adaptabilityMatrix)
        chromosomeMatrix = generate_next(chromosomeMatrix, adaptabilityMatrix,space_num)

        # 画图
        plt.cla()
        x = np.linspace(start, end, space_num)
        y = target_func(x)
        plt.plot(x, y)
        x1 = numpy.array(list(map(lambda x: x / float(space_num) * (end - start), chromosomeMatrix)))
        y1 = target_func(x1)
        # print(y1)
        plt.scatter(x1, y1, color='red')
        plt.title("{} th".format(i + 1))
        plt.pause(1)

    print("end.")
    print(list(map(lambda x: x / float(10000) * 5, chromosomeMatrix)))

    plt.ioff()
    plt.show()


def target_func(x):
    # 这里写下你的目标函数
    # return -x ** 2 + 5 * x + 1
    return 10 * np.sin(5 * x) + 7 * np.fabs(x - 5) + 10


if __name__ == '__main__':
    ga_algo(50, 100, target_func, 0, 5, 10000)

##bitopt.py

# 对正整数进行二进制操作
class Bit:
    def __init__(self, in_num):
        self._storage_num = in_num
        for item in range(0, in_num + 1):
            if 2 ** item >= in_num + 1:
                self._len = item
                break

    def is_valid_index(self, index):
        if index <= self._len - 1 and self._len >= 0:
            return True
        else:
            return False

    def ret_num(self):
        return self._storage_num

    def ret_len(self):
        return self._len

    def set_num(self, in_num):
        self._storage_num = in_num
        for item in range(1, in_num):
            if 2 ** item >= in_num + 1:
                self._len = item
                break

    # 返回给定位上的值
    def __getitem__(self, index):
        if self._storage_num & (1 << index) == 0:
            return 0
        else:
            return 1

    # 给指定位赋值
    def __setitem__(self, index, value: bool):
        if value is True:
            self._storage_num = self._storage_num | (1 << index)  # 将指定位置一
        else:
            self._storage_num = self._storage_num & (~(1 << index))  # 将指定位清零

    # 给指定位取反
    def reverse(self, index):
        self._storage_num = self._storage_num ^ (1 << index)


# 两个Bit应该是同一个长度
def cross(bit_a: Bit, bit_b: Bit, index_start, index_end):
    max_index = max(bit_a.ret_len(), bit_b.ret_len()) - 1
    if 0 <= index_start <= index_end <= max_index:
        to_clear_high = 2 ** (index_end + 1) - 1
        to_clear_low = ~(2 ** index_start - 1)
        a_mid = bit_a.ret_num() & to_clear_high & to_clear_low  # 得到a中间  0000aaaaa0000
        b_mid = bit_b.ret_num() & to_clear_high & to_clear_low  # 得到b中间  0000bbbbb0000
        bit_a.set_num(bit_a.ret_num() & (~a_mid))  # 将中间清零 => aaaa00000aaaa
        bit_a.set_num(bit_a.ret_num() | b_mid)  # 将b的中间放到a的中间 最终得到 aaaabbbbbaaaa
        bit_b.set_num(bit_b.ret_num() & (~b_mid))  # 同样 => bbbb00000bbbb
        bit_b.set_num(bit_b.ret_num() | a_mid)  # 最终得到 bbbbaaaaabbbb
        return True
    else:
        return False