数据挖掘算法实现

  1 #include <iostream>
  2 #include <string>
  3 #include <cstring>
  4 #include <vector>
  5 #include <list>
  6 #include <map>
  7 #include <algorithm>
  8 #include <cstdlib>
  9 #include <cstdio>
 10 #include <cmath>
 11 
 12 using namespace std;
 13 
 14 class Node
 15 {
 16 public:
 17     vector<int> next;
 18     string attr;
 19     string ans;
 20     //Node() next(), attr(""), ans(""){}
 21 };
 22 
 23 const string yes = "yes";
 24 const string no = "no";
 25 const int attribute_name_size = 6;
 26 vector< vector<string> > data; //day weather temperature humidity wind play_or_not
 27 Node node[1000];
 28 int cnt_of_node = 0;
 29 
 30 void input()
 31 {
 32     string str;
 33     vector<string> tmp;
 34     while (cin >> str && str != "end")
 35     {
 36         tmp.push_back(str);
 37         for (int i = 0; i < attribute_name_size-1; ++i)
 38         {
 39             cin >> str;
 40             tmp.push_back(str);            
 41         }
 42         data.push_back(tmp);
 43         tmp.clear();
 44     }
 45 }
 46 
 47 double calcEntropy(vector<vector<string> >& vec, string element)
 48 {
 49     double ans = 0;    
 50     map<string, int> mp;
 51     if (vec.size() <= 0) return -1;
 52     for (int j = 0; j < vec[0].size(); ++j)
 53     {
 54         if (vec[0][j] == element)
 55             for (int i = 1; i < vec.size(); ++i)
 56                 mp[vec[i][j]]++;            
 57     }
 58     double cnt = vec.size()-1;
 59     for (map<string, int>::iterator it = mp.begin(); it != mp.end(); ++it)
 60     {
 61         double p = (it->second)/cnt;
 62         ans -= p*log2(p);
 63     }
 64     return ans;
 65 }
 66 
 67 double calcInfo(vector<vector<string> >& vec, int idx)
 68 {
 69     double ans = 0;
 70     if (vec.size() <= 1) return -1;
 71     map<string, map<string, int> > mp;
 72     int len = vec[0].size();
 73     int size = vec.size()-1;
 74 
 75     for (int j = 1; j < vec.size(); ++j)
 76         mp[vec[j][idx]][vec[j][len-1]]++;
 77     for (map<string, map<string, int> >::iterator it = mp.begin(); it != mp.end(); ++it)
 78     {
 79         int ys = 0, nt = 0;
 80         for (map<string, int>::iterator itr = (it->second).begin(); itr != (it->second).end(); ++itr)
 81         {
 82             if (itr->first == yes) ys += itr->second;
 83             if (itr->first == no) nt += itr->second;            
 84         }
 85         ans = -(ys+nt)/size*(-ys/(ys+nt)*log2(ys/(ys+nt)) - nt/(ys+nt)*log2(nt/(ys+nt)));
 86     }
 87     return ans;
 88 }
 89 
 90 int findBestAttribute(vector<vector<string> >& tmp)
 91 {
 92     if (tmp.size() <= 1) return -1;
 93     int len = tmp[0].size();
 94     string result = tmp[0][len-1];
 95     vector<double> v;
 96     double info_result = calcEntropy(tmp, result);
 97     for (int i = 0; i < len; ++i)
 98         v.push_back(calcInfo(tmp, i));
 99     double max_info_gain = 0;
100     int idx = 0;
101     for (int i = 0; i < v.size(); ++i)
102     {
103         if (info_result-v[i] > max_info_gain)
104             max_info_gain = info_result-v[idx=i];
105     }
106     return idx;
107 }
108 
109 void work(vector< vector<string> >& source, int now_node_num)
110 {
111     int idx = 0;
112     idx = findBestAttribute(source);
113     vector<int> vis(source.size(), 0);
114     vector<string> attribute_tmp;
115     for (int i = 0; i < source[0].size(); ++i)
116         if (i != idx) attribute_tmp.push_back(source[0][i]);
117     int len = source[0].size();
118     for (int i = 1; i < source.size(); ++i)
119     {
120         if (vis[i]) continue;
121         map<string, int> mp;
122         for (int j = i; j < source.size(); ++j)
123         {
124             if (source[j][idx] == source[i][idx])
125             {
126                 mp[source[j][len-1]]++;
127                 vis[j] = 1;
128             }
129         }
130         node[now_node_num].next.push_back(++cnt_of_node);
131         node[cnt_of_node].attr = source[i][idx];
132         if (mp.size() == 1)
133         {
134             node[cnt_of_node].ans = source[i][len-1];    
135             node[cnt_of_node].next.clear();
136         }
137         else
138         {
139             vector<vector<string> > vs;
140             for (int j = 0; j < source.size(); ++j)
141             {
142                 vector<string> tmp;
143                 for (int k = 0; k < source[0].size(); ++k)
144                 {
145                     if (k == idx) continue;
146                     tmp.push_back(source[j][k]);    
147                 }
148                 vs.push_back(tmp);
149             }
150             work(vs, cnt_of_node);
151         }
152     }
153 }
154 
155 void outputSourceData()
156 {
157     for (int i = 0; i < data.size(); ++i)
158     {
159         for (int j = 0; j < data[i].size(); ++j)
160             cout << data[i][j] << ‘\t‘;
161         cout << endl;
162     }
163 }
164 
165 int main()
166 {
167         
168     return 0;
169 }