公司客户最近要做一个在线考试系统,其中难点在于自动组卷,因为普通的随机方法难度不好掌握,所以领导希望采用遗传算法。算法研究的任务领导交给了我,希望能在端午放假回来看到结果。而我之前并没有听说过遗传算法(孤陋寡闻),但领导分配的任务我不可能说不做(不做回家种地去),所以硬着头皮接了下来,开始GOOGLE遗传算法原理。其中一篇博文基于遗传算法自动组卷的实现对我帮助很大,同时我也联系了此博文的作者,希望能得到他的指点。没想到下午就收到回信,说这篇文章只是纯理论的研究。真正的项目早已找不到了。另外信中给了我几篇关于遗传算法的资料,给了我最直接的帮助。废话不多说,下面直接给代码,代码不难,我也不做解释,请有兴趣的童鞋自己研究(代码现在只是在测试阶段,写得很乱,将就着看吧):
using System; using System.Windows.Forms; using System.IO; namespace GA { public partial class Form1 : Form { TTm[] TP; int _ts = 0; int n = 10; int m = 12; int Pc = 50; //杂交的概率 int Pm = 80; //变异的概率 decimal _nd = 2; int[] Fs = { 2, 2, 2, 3, 3, 3, 5, 5, 5, 5, 5, 5, 5, 5, 10, 10, 10, 10, 15, 15, 15, 15, 15, 20, 20, 20, 20 }; //题目分数 int[] Nd = { 1, 1, 1, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 4, 4, 4, 4, 4, 5, 5, 5, 5 }; //题目难度 public Form1() { InitializeComponent(); } private void button1_Click(object sender, EventArgs e) { n = Fs.Length; m = Fs.Length; TP = new TTm[n]; var P = TP; int E, t; for (int i = 0; i < n; i++) { P[i].T = new KT[m]; } Initialize(P); if (!textBox4.Text.Equals("")) _nd = decimal.Parse(textBox4.Text); t = 0; E = Evaluate(P); decimal _result = 0; while (P[E].f < 100 || _ts < 12 || Math.Round((decimal)P[E].nd / _ts, 2) < _nd) //分数小于100或者题数小于12或者难度小于2继续循环 { Crossover(P);//杂交 Mutation(P);//变异 E = Evaluate(P);//评估种群 t = t + 1; textBox1.Text = t.ToString(); textBox2.Text = P[E].f.ToString(); Print(P[E]);//输出 if (_ts != 0) { _result = Math.Round((decimal)P[E].nd / _ts, 2); textBox4.Text = _result.ToString();//(P[E].nd /_ts) } Application.DoEvents();//使程序响应事件,避免假死无法退出现象 if (P[E].f == 100 && _ts >= 12 && _result >= _nd) //总分等于100并且题数大于等于12并且难度系数大于等于2停止循环 { _ts = 0; break; } Select(P);//择优 } } /// <summary> /// 初始化种群 /// </summary> /// <param name="P"></param> private void Initialize(TTm[] P) { int i, j, G; for (i = 0; i < n; i++) { for (j = 0; j < m; j++) { P[i].T[j].Fs = Fs[j]; P[i].T[j].nd = Nd[j]; P[i].T[j].Se = 0; } } Random rnd = new Random(); int temp = rnd.Next(m); for (i = 0; i < n; i++) { G = 0; while (Math.Abs(G - 105) > 10 && G < 130) { if (P[i].T[temp].Se == 0) { P[i].T[temp].Se = 1; G = G + P[i].T[temp].Fs; P[i].T[temp].Se = 0; } } } } /// <summary> /// 评估种群 /// </summary> /// <param name="P"></param> private int Evaluate(TTm[] P) { int i, j, G, D = 0, result = 0; for (i = 0; i < n; i++) { G = 0; for (j = 0; j < m; j++) { if (P[i].T[j].Se == 1) { G = G + P[i].T[j].Fs; D = D + P[i].T[j].nd; } } P[i].f = 100 - Math.Abs(G - 100); P[i].nd = D; if (P[i].f > P[result].f && P[i].nd > P[result].nd) result = i; } return result; } /// <summary> /// 杂交 /// </summary> /// <param name="P"></param> private void Crossover(TTm[] P) { int i = 0, j = 1, k, t; Random rnd = new Random(); while (i < n - 1) { if (rnd.Next(101) > Pc) { //for (k = rnd.Next(m); k < m; k++)//一点杂交 for (k = rnd.Next(m); k <= rnd.Next(m); k++)//两点杂交 { t = P[i].T[k].Se; P[i].T[k].Se = P[j].T[k].Se; P[j].T[k].Se = t; } } i += 2; j += 1; } } /// <summary> /// 变异 /// </summary> /// <param name="P"></param> private void Mutation(TTm[] P) { int i; Random rnd = new Random(); for (i = 0; i < n; i++) { if (rnd.Next(101) > Pm) { P[i].T[rnd.Next(m)].Se = Convert.ToInt32(!Convert.ToBoolean(P[i].T[rnd.Next(m)].Se)); } } } /// <summary> /// 择优 /// </summary> /// <param name="P"></param> private void Select(TTm[] P) { int i, j; TTm Tm; for (i = 0; i < n - 1; i++) //对种群按优劣排序 { for (j = i + 1; j < n; j++) { if (P[i].f > P[j].f) { Tm = P[i]; P[i] = P[j]; P[j] = Tm; } } } for (i = 0; i <= (n - 1) / 2; i++) //淘汰50%劣等品种 { P[n - 1 - i] = P[i]; } } /// <summary> /// 输出 /// </summary> /// <param name="Tm"></param> private void Print(TTm Tm) { string s1, s2; int i; _ts = 0; s1 = "题号:"; s2 = "分值:"; for (i = 0; i < m; i++) { if (Tm.T[i].Se == 1) { s1 = s1 + (i+1) + " "; s2 = s2 + Tm.T[i].Fs + " "; _ts++; } } textBox3.Text = s1 + "\r\n" + s2 + "\r\n题数:" + _ts; } } public struct KT { public int Fs; public int nd; public int Se; } public struct TTm { public KT[] T; public int f; public int nd; } }
下面的图是运行结果:
转自:http://www.cnblogs.com/JasonChou/archive/2010/06/10/1755566.html