人工智能遗传算法求解函数的最大值问题

#include <iostream> #include <time.h> //产生随机数要用到使每次产生的数不同。 #include <math.h> using namespace std; const double pi = 3.1415926; const int MAX = 4194304; const int MIN = 0; class Individuality //个体类 { private: int chromosome; //染色体 public: void set(int chromosome) { this->chromosome = chromosome; } Individuality operator =(Individuality c)//重载等号 { this->chromosome = c.chromosome; return *this; } bool operator ==(Individuality c)//判相等 { return this->chromosome == c.chromosome; } float resolve() //通过染色体取得x的值 { return -1.0 + (float)chromosome * 3.0 / (MAX - 1); } float evaluate() //f() { return resolve() * (float)sin(10*pi*resolve()) + 1.0; } void print() { cout << '\t'; for(int j = 21; j >= 0; j--) //以下循环是在以二进制串的形式打印染色体 { if((1<<j) & chromosome) cout << '1'; else cout << '0'; } cout << "\t\tx = " << resolve() << "\tf(x) = " << evaluate() << endl; } //以下是对当前个体进行变异的操作 Individuality variate() { int i = rand() % 21 + 1; this->chromosome ^= 1<<i; return *this; } //以下是两个个体进行交叉，并且返回两个新个体的操作 void crisscross(Individuality prnt1, Individuality prnt2, Individuality &child1, Individuality &child2) { int i = rand() % 21 + 1; int temp1 = prnt1.chromosome; int temp2 = prnt2.chromosome; int temp = 0; for(; i < 22; i++) temp += 1<<i; temp1 &= temp; temp2 &= temp; prnt1.chromosome &= ~temp; prnt2.chromosome &= ~temp; prnt1.chromosome |= temp2; prnt2.chromosome |= temp1; child1 = prnt1; child2 = prnt2; } }; //建立一个种群的类，并且有固定的大小 const int POP_SIZE = 200; /*================================ 每次遗传，选出f(x)的排名在前50%的个体进行遗传（排名通过希尔排序实现）， 都会有约1%的个体变异，10%的个体发生交叉遗传，其余的直接遗传。每次遗传都 记录下本次f(x)为最大的个体Max。遗传150次，如果过程中发现已有30代的Max一 直不变了，说明已达到最优，基本不需要再遗传了，所以提前跳出循环。 ===================================*/ class Population //种群类 { private: Individuality ind[POP_SIZE]; public: Population() { for(int i = 0; i < POP_SIZE; i++) ind[i].set( (((double)rand()/(double)RAND_MAX) * MAX + MIN)); } void shellSort() //希尔排序 { int gap, i, j; Individuality temp; for(gap = POP_SIZE/2; gap > 0; gap /= 2) for(i = gap; i < POP_SIZE; i++) for(j=i-gap; j>=0 && ind[j].evaluate() < ind[j+gap].evaluate(); j -= gap) { temp = ind[j]; ind[j] = ind[j+gap]; ind[j+gap] = temp; } } void inherit() { Population::shellSort(); const int NT = POP_SIZE / 2; int nc = (rand() % (POP_SIZE/10) + (POP_SIZE/4)) / 2; int nv = rand() % (POP_SIZE/100+1) + (POP_SIZE/100); int i, n1, n2; Individuality temp[NT]; for(i = 0; i < NT; i++) temp[i] = ind[i]; for(i = 0; i < nv; i++) { n1 = rand() % NT; ind[i] = temp[n1].variate(); } for(i = nv; i < nc; i += 2) { n1 = rand() % NT; n2 = rand() % NT; Individuality temp1, temp2; temp->crisscross(temp[n1], temp[n2], temp1, temp2); ind[i] = temp1; ind[i+1] = temp2; } for(i = nv+nc*2; i < POP_SIZE; i++) { n1 = rand() % NT; ind[i] = temp[n1]; } } Individuality getMax() { Individuality max = ind[0]; for(int i = 0; i < POP_SIZE-1; i++) { if( ind[i+1].evaluate() > ind[i].evaluate() ) max = ind[i+1]; } return max; } void traverse() { for(int i = 0; i < POP_SIZE; i++) ind[i].print(); cout << endl; } }; int main() { srand( (unsigned)time( NULL ) ); Population a; a.traverse(); int count = 0; int gen = 0; for(int i = 0; i < 150; i++) { Individuality temp = a.getMax(); a.inherit(); if(a.getMax() == temp) count++; if(count > 30) break; a.traverse(); gen++; } cout << "The max is:\n"; a.getMax().print(); cout << "After " << gen << " generations.\n"; return 0; }