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.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 }
GenticTsp.cpp
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 }
maintest.cpp
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
city.txt
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+。
时间： 2024-08-30 10:41:47