通过构造函数制作的所有对象都具有相同的向量 [英] All objects made through constructor have the same vectors

问题描述

我是C ++的新手，我正在尝试创建一种基本的遗传算法.我创建了一个染色体类，并希望创建一个Society类，该类使用随机生成的基因"生成这些染色体的向量.基因是染色体中的向量，其值为0或1.我正在测试染色体的构造函数，并且所有对象都具有相同的基因向量.如何使构造函数生成随机值?我在下面包含了代码.任何其他编码实践或优化技巧也将不胜感激.

I'm new to C++ and I am trying to create a basic genetic algorithm. I created a Chromosome class and want to create a Society class that generates a vector of these Chromosomes with randomly generated "genes". Genes being the vector in the Chromosome that holds values of 0 or 1. I was testing out the Chromosome constructor, and all of the objects have the same gene vectors. How can I make the constructor generate random values? I have included code below. Any other coding practice or optimization tips would also be extremely appreciated.

Source.cpp

Source.cpp

#include "Chromosome.h"
#include "Society.h"

using namespace std;

int main()
{
    Chromosome demo = Chromosome::Chromosome();
    Chromosome demo2 = Chromosome::Chromosome();
    return 1;
}

Chromosome.h

Chromosome.h

#pragma once
#include <vector>
using namespace std;

class Chromosome
{
private:
    int fitness;
    vector<int> genes;

public:
    Chromosome();

    void generateGenes();

    int calculateFitness(),
        getFitness();

    vector<int> getGenes();
    void setGenes(vector<int> child);
};

Chromosome.cpp

Chromosome.cpp

#include "Chromosome.h"
#include <cstdlib>
#include <ctime> 
#include <numeric>
using namespace std;

Chromosome::Chromosome()
{
    generateGenes();
    Chromosome::fitness = calculateFitness();
}

void Chromosome::generateGenes()
{
    srand(time(NULL));
    for (unsigned i = 0; i < 10; i++)
    {
        unsigned chance = rand() % 5;
        Chromosome::genes.push_back((!chance)? 1 : 0);
    }
}

int Chromosome::calculateFitness()
{
    int sum = 0;
    for (unsigned i = 0; i < Chromosome::genes.size(); i++)
    {
        sum += Chromosome::genes[i];
    }
    return sum;
}

int Chromosome::getFitness()
{
    return Chromosome::fitness;
}

vector<int> Chromosome::getGenes()
{
    return Chromosome::genes;
}

void Chromosome::setGenes(vector<int> child)
{
    Chromosome::genes = child;
}

推荐答案

您将具有相同值 time(NULL)的随机数生成器作为种子.彼此之后的两个呼叫将返回相同的 time_t .您将首先生成一组随机数，然后重置随机数生成器并再次生成它们.

You seed the random number generator with the same value time(NULL). Two calls after eachother will return the same time_t. You'll generate one set of random numbers first, then reset the random number generator and generate them again.

在整个程序运行期间仅调用 srand() 一次.

Only call srand() once during the whole program run.

此外，请使用 < random> 而是获得更好/更快的随机数生成器.

Also, use <random> instead to get better/faster random number generators.

使用< random> 代替 rand()％5; :

#include <random>

// A function to return a random number generator.
inline std::mt19937& generator() {
    // the generator will only be seeded once since it's static
    static std::mt19937 gen(std::random_device{}());
    return gen;
}

// A function to generate unsigned int:s in the range [min, max]
int my_rand(unsigned  min, unsigned  max) {
    std::uniform_int_distribution<unsigned > dist(min, max);
    return dist(generator());
}

然后称呼它:

unsigned chance = my_rand(0, 4);

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