k_means算法的C++实现

首先画出k_means算法的流程图：

具体代码，C++实现：

#include <iostream>
#include <fstream>
#include <cmath>
#include <ctime>
using namespace std;

const int N = 10000;

typedef struct {
    double x1,x2;
    int flag;
}oneNode;

oneNode node[N];
int k,n;

void DataInput();
void SetInitial(oneNode *p,oneNode *q);
void SetQzero(oneNode &qi);
bool GetExist(int xm,int *sb,int i);
void DataIteration(oneNode *p,oneNode *q,double &E1,double &E3);
double GetRange(oneNode &node1,oneNode &node2);
bool JudgeCondition(oneNode *p,oneNode *q);
void DataOutput(oneNode *p,double E1,double E3);

int main(){
    int E2=0;
    double E1 = 0,E3;
    n = 0;


    DataInput();                                 //将txt文件中记录读入，存储到oneNode列表中

    cout<<"请输入新的聚类数目：";
    cin>>k;
    oneNode *p = new oneNode[k];
    oneNode *q = new oneNode[k];

    SetInitial(p,q);                             //初始化开始的k个聚类中心

    
    DataIteration(p,q,E1,E3);                    //循环处理每条记录，获得新的聚类中心

    DataOutput(p,E1,E3);                         //输出程序运行结果

    delete[] q;
    delete[] p;
    return 0;
}




void DataInput(){
    ifstream ifs;                                //通过txt文件，读入所有记录,将记录存储到oneNode列表中
    ifs.open("D:k_means\aa11.txt");
    if (!ifs.is_open())
    {
        cout<<"文件读取失败"<<endl;
        exit(0);
    }


    while (!ifs.eof())                           //将txt文件中记录，存储到node[]中
    {
        ifs>>node[n].x1;
        ifs>>node[n].x2;
        n++;
    }
}



void SetInitial(oneNode *p,oneNode *q){
    int xm;
    int *sb = new int[k];
    srand((unsigned)time(0));
    for (int i = 0;i < k;i++)
    {
        do 
        {
            xm = rand()%n;
        } while (GetExist(xm,sb,i));
        sb[i] = xm;

        p[i] = node[xm];

        SetQzero(q[i]);
    }
    delete[] sb;
}


void SetQzero(oneNode &qi){
    qi.x1 = 0;
    qi.x2 = 0;
    qi.flag = 0;
}




bool GetExist(int xm,int *sb,int i){
    bool b = false;
    for (int j = 0;j < i;j++)
    {
        if (sb[j] == xm)
        {
            b = true;
            break;
        }
    }
    return b;
}


void DataIteration(oneNode *p,oneNode *q,double &E1,double &E3){
    int i,j,E2 = 0;
    bool b;
    do 
    {
        E3 = 0;
        for(i = 0;i < n;i++){
            double mm = GetRange(node[i],p[0]);
            int m = 0;
            for (j = 1;j < k;j++)
            {
                double nn = GetRange(node[i],p[j]);
                if (mm > nn)
                {
                    mm = nn;
                    m = j;
                }
            }
            node[i].flag = m;
            E3 +=  GetRange(node[i],p[m]);
            q[m].x1 += node[i].x1;
            q[m].x2 += node[i].x2;
            q[m].flag += 1;
        }
        if (E2 == 0)
        {
            E1 = E3;
        }else if(E2 > 0){
            if (E1 <= E3)
            {
                break;
            }else{
                E1 = E3;
            }
        }
        E2++;
        for (i = 0;i < k;i++)
        {
            if (q[i].flag != 0)
            {
                q[i].x1 = q[i].x1/q[i].flag;
                q[i].x2 = q[i].x2/q[i].flag;
            }
        }
        b = JudgeCondition(p,q);
        for (i = 0;i < k;i++)
        {
            p[i] = q[i];

            SetQzero(q[i]);
        }
    } while (b);

}

double GetRange(oneNode &node1,oneNode &node2){
    return pow(node1.x1-node2.x1,2)+pow(node1.x2-node2.x2,2);
}


bool JudgeCondition(oneNode *p,oneNode *q){
    bool bo = false;
    for (int i = 0;i < k;i++)
    {
        if (pow(p[i].x1-q[i].x1,2)+pow(p[i].x2-q[i].x2,2) >= 5.0)
        {
            bo = true;
            break;
        }

    }
    return bo;
}


void DataOutput(oneNode *p,double E1,double E3){
    if (E1 != E3){
        cout<<"操作失败"<<endl;
    }else{
        cout<<"本次总体误差是："<<E1<<endl;
        ofstream ofile("D://k_means/aa11result.txt");
        for (int i = 0;i < k;i++)
        {
            ofile<<"第"<<i+1<<"个聚类中心是："<<"("<<p[i].x1<<","<<p[i].x2<<")"<<endl<<"属于第"<<i+1<<"个聚类的所有点是："<<endl;
            for (int j = 0;j < n;j++)
            {
                if (node[j].flag == i)
                {
                    ofile<<node[j].x1<<" "<<node[j].x2<<endl;
                }
            }
        }

    }
}