knn算法C++实现

knn的C++实现，有不对的地方请各位指正！谢谢！

knn原理请见：http://blog.csdn.net/u013593585/article/details/51284537

#include <iostream>#include <vector>#include <fstream>#include <string>#include <sstream>using namespace std;typedef vector<float> Tuple;const int k = 4;const int dims = 3;const int categories = 3; // 1,2,3int RunKnn(vector<Tuple>& trainData,vector<int>& label, Tuple& testData, int count);float getDist(Tuple& trainData, Tuple& testData);void sortDist(Tuple& dists, vector<int>& label, int count);void showDist(Tuple& dists, int count);int main(){// 准备训练数据cout << "Preparing the Trainning data----" << endl;string fileName = "datingTestSet.txt";fstream file(fileName);if (!file){cout << "can not open the file " << endl;return 0;}vector<Tuple> trainData;vector<int> label;int count = 0;while(!file.eof()){string str;getline(file,str);stringstream ss(str);ss << str;Tuple temp(dims,0);for(int i = 0; i < dims; i++)ss >> temp[i];trainData.push_back(temp);int t;ss >> t;label.push_back(t);count ++;}//训练数据归一化Tuple maxnum(dims,0);Tuple minnum(dims,0);for (int i = 0; i < count; i++){for (int j = 0; j < dims; j++){if (trainData[i][j] > maxnum[j])maxnum[j] = trainData[i][j];if (trainData[i][j] < minnum[j])minnum[j] = trainData[i][j];}}float chazhi;for (int i = 0; i < dims; i++){chazhi = maxnum[i] - minnum[i];for (int j = 0; j < count; j++)trainData[j][i] = (trainData[j][i] - minnum[i])/chazhi;}//准备测试数据cout << "Preparing the testing data-----" << endl;int ind = 80;Tuple testData = trainData[ind];int truthLabel = label[ind];//knn开始cout << "Running" << endl;int testLabel = RunKnn(trainData,label,testData,count);cout << "testLabel: " << testLabel << endl;cout <<  "truthLabel: " << truthLabel << endl;if(testLabel == truthLabel)cout << "Yes!" << endl;elsecout << "No!" << endl;system("pause");return 0;}float getDist(Tuple& trainData, Tuple& testData){float dist = 0;for(int i = 0; i < dims; i++)dist += (trainData[i] - testData[i]) * (trainData[i] - testData[i]);return dist;}void sortDist(Tuple& dists, vector<int>& label,int count){for (int i = 1; i < count; i++){for (int j = 0; j < count-i-1; j++){if(dists[j] > dists[j+1]){float temp1 = dists[j];dists[j] = dists[j+1];dists[j+1] = temp1;int temp2 = label[j];label[j] = label[j+1];label[j+1] = temp2;}}}}int RunKnn(vector<Tuple>& trainData,vector<int>& label, Tuple& testData, int count){//计算距离Tuple dists(count,0);for(int i = 0; i < count; i++)dists[i] = getDist(trainData[i],testData);showDist(dists,count);//距离排序sortDist(dists,label,count);showDist(dists,count);//统计前k个;int sumLabels[3] = {0};for(int i = 0; i < k; i++)sumLabels[label[i]-1] ++;//统计最多的那个labelint temp = 0;int testLabel;for(int i = 0; i < k; i++){if(sumLabels[i] > temp){temp = sumLabels[i];testLabel = i + 1;}}return testLabel;}void showDist(Tuple& dists, int count){for (int i = 0; i < count; i++)cout << dists[i] << " ";cout << endl;}