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心血来潮把GA_TSP问题用C++封装起来搞了一遍，期间真是收益不小。
主要是用STL中的vector和list，结构体赋值中遇到了一些难点，原谅我自己是一棵白菜。
选择方法：用种群前面最优的20%代替后面的20%进行淘汰(当然这个比例可以自己拟定，修改代码中得pm_即可)。
变异方法：交换一个路径上随机产生的两个城市。
交叉方法：三交换启发交叉(THGA)。
genticTsp.h 代码如下：
1 #ifndef GENTIC_TSP_H_ 2 #define GENTIC_TSP_H_ 3 #include <iostream> 4 #include <vector> 5 #include <string> 6 #define CITIES 99 7 #define UNITS 50 8 #define MAX_GEN 15 9 10 11 struct city{ 12 int id; 13 int x; 14 int y; 15 }; 16 17 struct unit{ 18 double length; 19 std::vector<int> path; 20 bool operator<(const struct unit &other) const 21 { 22 return length < other.length; 23 } 24 }; 25 26 27 class GenticTSP{ 28 public: 29 GenticTSP(); 30 void initMatrix(const std::string &filename);//file to matrix 31 void initGroup();//shuffle a group 32 double lenOfUnit(unit &p);// 33 int searchCity(unit &, int id);//search a city‘s id for cross 34 void selectGroup(); 35 void crossUnits(unit &p, unit &q, unit &r); 36 void mutateGroup(); 37 void evoluteGroup(); 38 void printBestUnit(); 39 ~GenticTSP(); 40 private: 41 unit bestUnit_; 42 double pm_;// mutate probability 43 double ps_;//save probability 44 45 }; 46 47 #endif /*GENTIC_TSP_H_*/
genticTsp.cpp代码如下：
1 #include "GenticTSP.h" 2 #include <iostream> 3 #include <fstream> 4 #include <string> 5 #include <vector> 6 #include <list> 7 #include <algorithm> 8 #include <math.h> 9 #include <time.h> 10 #include <string.h> 11 12 using namespace std; 13 14 city cities[CITIES]; 15 unit group[UNITS]; 16 double cityMatrix[CITIES][CITIES]; 17 18 GenticTSP::GenticTSP() 19 :pm_(0.2), ps_(0.8) 20 { 21 22 } 23 24 GenticTSP::~GenticTSP() 25 { 26 27 } 28 29 void GenticTSP::initMatrix(const string &filename) 30 { 31 int i, j; 32 ifstream in(filename); 33 for(i = 0; i < CITIES; ++i) 34 { 35 36 in >> cities[i].id >> cities[i].x >> cities[i].y; 37 } 38 39 for(i = 0; i < CITIES; ++i) 40 { 41 cityMatrix[i][i] = 0; 42 for(j = i + 1; j < CITIES; ++j) 43 { 44 cityMatrix[i][j] = sqrt((cities[i].x - cities[j].x) * (cities[i].x - cities[j].x) + (cities[i].y - cities[j].y) * (cities[i].y - cities[j].y)); 45 cityMatrix[j][i] = cityMatrix[i][j]; 46 } 47 48 } 49 } 50 51 52 //calculate the path-lenght of each path 53 double GenticTSP::lenOfUnit(unit &unit) 54 { 55 unit.length = 0; 56 for(int j = 0; j < CITIES - 1; ++j) 57 { 58 unit.length += cityMatrix[unit.path[j]][unit.path[j + 1]]; 59 } 60 61 //回到起始城市 62 unit.length += cityMatrix[unit.path[0] ][unit.path[CITIES - 1] ]; 63 64 return unit.length; 65 } 66 67 68 //init group of various paths 69 void GenticTSP::initGroup() 70 { 71 vector<int> tmp; 72 for(int i = 0; i < CITIES; ++i) 73 tmp.push_back(i); 74 75 for(int i = 0; i < UNITS; ++i) 76 { 77 random_shuffle(tmp.begin(),tmp.end()); 78 group[i].path = tmp; 79 group[i].length = lenOfUnit(group[i]); 80 } 81 } 82 83 //for test 84 void printlist(list<int> &path) 85 { 86 for(list<int>::iterator it = path.begin(); it != path.end(); ++it){ 87 cout << *it << " "; 88 } 89 cout << endl; 90 } 91 92 void rightRotateList(list<int> &path, list<int>::iterator ptr, list<int>::iterator res) 93 { 94 path.insert(ptr, res, path.end()); 95 path.erase(res, path.end()); 96 } 97 98 99 void GenticTSP::selectGroup() 100 { 101 int selected = UNITS * ps_; 102 int non_selected = UNITS - selected; //防止取整丢失，所以直接采用减去selected 103 for(int i = 0; i < UNITS; ++i) 104 { 105 group[i].length = lenOfUnit(group[i]); 106 } 107 sort(group, group + UNITS); 108 109 /*群体规模保持不变 110 *被淘汰的个体数目为non_selected 111 *用被选择的前non_seleted个个体替代之 112 */ 113 for(int i = 0; i < non_selected; ++i) 114 { 115 group[UNITS-1-i].path = group[i].path; 116 group[UNITS-1-i].length = group[i].length; 117 118 /* WARNING: 119 * error:memcpy(&group[UNITS-1-i], &group[i], sizeof(unit)); 120 * 不能用memcpy 121 * 因为unit是自定义的结构体 122 * 其中的vector类型也不是原生的数据类型 123 * 如若使用，需要自定义构造函数 124 */ 125 } 126 } 127 128 129 void GenticTSP::evoluteGroup() 130 { 131 for(int i = 0; i < MAX_GEN; ++i) 132 { 133 selectGroup(); 134 135 for(int j = 0; j < UNITS-2;) 136 { 137 crossUnits(group[j], group[j+1], group[j+2]); 138 j += 2; 139 } 140 141 mutateGroup(); 142 } 143 144 } 145 146 147 void GenticTSP::mutateGroup() 148 { 149 srand(time(NULL)); 150 int num; 151 int pos1, pos2; 152 int tmp; 153 int sum = UNITS * pm_; //变异的总数= 群体数 * 变异概率 154 while(sum--) 155 { 156 //随机选取一个发生变异的unit 157 num = rand() % UNITS; 158 //随机选取两个path上变异的城市，采用交换两个城市的方法进行变异 159 pos1 = rand() % CITIES; 160 pos2 = rand() % CITIES; 161 162 //如果相同则不能算是变异，这里用while确保变异 163 while(pos1 == pos2) 164 pos2 = rand() % CITIES; 165 166 tmp = group[num].path[pos1]; 167 group[num].path[pos1] = group[num].path[pos2]; 168 group[num].path[pos2] = tmp; 169 170 //更新该变异后path的长度 171 lenOfUnit(group[num]); 172 } 173 } 174 175 176 177 178 void GenticTSP::crossUnits(unit &u1, unit &u2, unit &u3) 179 { 180 //将路径存储在list类型的容器中便于后面的插入操作 181 list<int> path1(u1.path.begin(), u1.path.end()); 182 list<int> path2(u2.path.begin(), u2.path.end()); 183 list<int> path3(u3.path.begin(), u3.path.end()); 184 //随机产生起始城市的id， 并将位置默认为第一个位置 185 srand((int)time(0)); 186 int cityID = rand() % CITIES; 187 list<int>::iterator res1, res2, res3; 188 res1 = find(path1.begin(), path1.end(), cityID); 189 res2 = find(path2.begin(), path2.end(), cityID); 190 res3 = find(path3.begin(), path3.end(), cityID); 191 if(res1 == path1.end() || res2 == path2.end() || res3 == path3.end()) 192 { 193 cout << "city not found" << endl; 194 } 195 196 //将以随机选取的城市及其后面的城市右旋到序列首部 197 rightRotateList(path1, path1.begin(), res1); 198 rightRotateList(path2, path2.begin(), res2); 199 rightRotateList(path3, path3.begin(), res3); 200 201 list<int>::iterator ptr1, ptr2, ptr3; 202 ptr1 = path1.begin(); 203 ptr2 = path2.begin(); 204 ptr3 = path3.begin(); 205 206 /*CITIES个城市 207 *第一个城市在循环体外已经确定 208 *循环体内只要再执行CITIES - 2 次即可 209 *因为当执行倒数第二次后，最后一个也就是仅剩的一个也无需再循环了 210 */ 211 for(int k = 1; k < CITIES-1; ++k) 212 { 213 // cout << "______" << k<< "______" << endl; 214 int h1 = *ptr1; 215 double len1 = cityMatrix[h1][*(++ptr1)]; 216 int h2 = *ptr2; 217 double len2 = cityMatrix[h2][*(++ptr2)]; 218 int h3 = *ptr3; 219 double len3 = cityMatrix[h3][*(++ptr3)]; 220 221 //找出前两个城市距离最小的那个path中得第一个城市的编号 222 double len = (len1 <= len2) ? len1 : len2; 223 len = (len < len3) ? len : len3; 224 if(len == len1){ 225 cityID = *ptr1; 226 }else if(len == len2){ 227 cityID = *ptr2; 228 }else{ 229 cityID = *ptr3; 230 } 231 232 //与当前城市距离最小的下一个城市编号为cityID 233 res1 = find(ptr1, path1.end(), cityID); 234 res2 = find(ptr2, path2.end(), cityID); 235 res3 = find(ptr3, path3.end(), cityID); 236 if(res1 == path1.end() || res2 == path2.end() || res3 == path3.end()) 237 { 238 cout << "city not found in loop" << endl; 239 } 240 rightRotateList(path1, ptr1, res1); 241 rightRotateList(path2, ptr2, res2); 242 rightRotateList(path3, ptr3, res3); 243 244 //指针失效，需要重新定位 245 ptr1 = find(path1.begin(), path1.end(), cityID); 246 ptr2 = find(path2.begin(), path2.end(), cityID); 247 ptr3 = find(path3.begin(), path3.end(), cityID); 248 } 249 250 251 /*为了避免三个路径相同，所以这里在不改变路径的情况下替换起点城市，有利于接下来的交叉*/ 252 cityID = (rand() % CITIES); 253 res2 = find(path2.begin(), path2.end(), cityID); 254 rightRotateList(path2, path2.begin(), res2); 255 256 cityID = (rand() % CITIES); 257 res3 = find(path3.begin(), path3.end(), cityID); 258 rightRotateList(path3, path3.begin(), res3); 259 260 //交叉完之后再赋值给vector类型 261 u1.path.assign(path1.begin(), path1.end()); 262 u2.path.assign(path2.begin(), path2.end()); 263 u3.path.assign(path3.begin(), path3.end()); 264 } 265 266 267 //print top5 paths with length 268 void GenticTSP::printBestUnit() 269 { 270 for(int i = 0; i < 5; ++i) 271 { 272 cout << "Path" << i << ": "; 273 for(vector<int>::iterator it = group[i].path.begin(); it != group[i].path.end(); ++it){ 274 cout << *it << " "; 275 } 276 cout << endl << "length: " << group[i].length << endl; 277 } 278 }
maintest.cpp
1 #include <iostream> 2 #include <string> 3 #include <vector> 4 #include <fstream> 5 #include "GenticTSP.h" 6 using namespace std; 7 8 9 int main(int argc, const char *argv[]) 10 { 11 GenticTSP genticTsp; 12 genticTsp.initMatrix("city.txt"); 13 genticTsp.initGroup(); 14 genticTsp.evoluteGroup(); 15 genticTsp.selectGroup(); //进化后需要再一次选择，从而排序出最优序列 16 genticTsp.printBestUnit (); 17 18 return 0; 19 }
city.txt
1 6 4 2 15 15 3 24 18 4 33 12 5 48 12 6 57 14 7 67 10 8 77 10 9 86 15 10 6 21 11 17 26 12 23 25 13 32 35 14 43 23 15 55 35 16 65 36 17 78 39 18 87 35 19 3 53 20 12 44 21 28 53 22 33 49 23 47 46 24 55 52 25 64 50 26 71 57 27 87 57 28 4 72 29 15 78 30 22 70 31 34 71 32 42 79 33 54 77 34 66 79 35 78 67 36 87 73 37 7 81 38 17 95 39 26 98 40 32 97 41 43 88 42 57 89 43 64 85 44 78 83 45 83 98 46 5 109 47 13 111 48 25 102 49 38 119 50 46 107 51 58 110 52 67 110 53 74 113 54 88 110 55 2 124 56 17 134 57 23 129 58 36 131 59 42 137 60 53 123 61 63 135 62 72 134 63 87 129 64 2 146 65 16 147 66 25 153 67 38 155 68 42 158 69 57 154 70 66 151 71 73 151 72 86 149 73 5 177 74 13 162 75 25 169 76 35 177 77 46 172 78 54 166 79 65 174 80 73 161 81 86 162 82 2 195 83 14 196 84 28 189 85 38 187 86 46 195 87 57 194 88 63 188 89 77 193 90 85 194 91 8 211 92 12 217 93 22 210 94 34 216 95 47 203 96 58 213 97 66 206 98 78 210 99 85 204
用的city.txt这里的数据，据说最优路径代价是1100+，可是我用我的选择，变异，交叉方法目前来看最小代价只能达到1500+。
标签：style blog http io ar color os 使用 sp
原文地址：http://www.cnblogs.com/beatrice7/p/4142568.html
