K-means聚类

记录一点代码，C++写的K-means聚类算法。从Test_data.txt文件中读取数据，k-means分类后给每个样本点打上标签，并存入Resut_data.txt中，最后两行（标签为2的）是聚类中心。

/*****************************************
Copyright (c) 2015 Jingshuang Hu

@filename:demo.cpp
@datetime:2015.11.16
@author:HJS
@e-mail:jingshuang_hu@163.com
@blog:http://blog.csdn.net/hujingshuang
*****************************************/
#include <iostream>
#include <math.h>
#include "class_point.h"

using namespace std;

void read_text(Point *point);
void write_text(Point *point, Point *center);
double point_distance(Point A, Point B);
Point *k_means(Point *point);

int main()
{
	Point *center;
	Point point[1000];
	read_text(point);
	center = k_means(point);
	write_text(point, center);

	return 0;
}//end main
//K-means算法
Point *k_means(Point *point)
{
	Point *center = new Point[2];		//两个聚类中心
	Point *pre_center = new Point[2];
	center[0] = point[200];				//任意选取两个样本点作为聚类中心
	center[1] = point[800];
	double dis0 = 0, dis1 = 0;			//临时距离
	double sum0x = 0, sum0y = 0, sum1x = 0, sum1y = 0;
	int num0 = 0, num1 = 0;				//类的个数
	double d0 = 0, d1 = 0;
	do
	{
		pre_center[0] = center[0];
		pre_center[1] = center[1];
		for (int i = 0; i < 1000; ++i)
		{
			dis0 = point_distance(center[0], point[i]);
			dis1 = point_distance(center[1], point[i]);
			if (dis0 < dis1)
			{
				point[i].set_label(0);		//打上标签
				num0 += 1;					//统计个数
				sum0x += point[i].pos_x();
				sum0y += point[i].pos_y();
			}
			else
			{
				point[i].set_label(1);		//打上标签
				num1 += 1;					//统计个数
				sum1x += point[i].pos_x();
				sum1y += point[i].pos_y();
			}
		}//end for
		center[0].set_cursor(sum0x / num0, sum0y / num0);
		center[1].set_cursor(sum1x / num1, sum1y / num1);
		sum0x = sum0y = sum1x = sum1y = 0;
		num0 = num1 = 0;
		d0 = point_distance(center[0], pre_center[0]);//聚类中心不再有太大的变化，认为收敛
		d1 = point_distance(center[1], pre_center[1]);
	}while((d0 > 0.00001) || (d1 > 0.00001));//终止条件
	return center;
}//end function
//计算两点间距离
double point_distance(Point A, Point B)
{
	return sqrt(pow(A.pos_x() - B.pos_x(), 2) + pow(A.pos_y() - B.pos_y(), 2));
}
//读取样本点数据
void read_text(Point *point)
{
	FILE *fp = fopen("Test_data.txt","r");
	if (!fp)
	{
		cout << "打开文件失败！" << endl;
		return;
	}
	int i = 0;
	double x = 0, y = 0;
	while(!feof(fp))
	{
		fscanf(fp, "%lf", &x);
		fscanf(fp, "%lf", &y);
		point[i].set_cursor(x, y);
		++i;
	}
	fclose(fp);
	return;
}
//保存样本点数据（保留一位小数）
void write_text(Point *point, Point *center)
{
	FILE *fp = fopen("Result_data.txt", "w");
	for(int i = 0; i < 1000; ++i)
	{
		fprintf(fp, "%.1lf\t%.1lf\t%d\n", point[i].pos_x(), point[i].pos_y(), point[i].pos_label());
	}
	fprintf(fp, "%.1lf\t%.1lf\t%d\n", center[0].pos_x(), center[0].pos_y(), 2);
	fprintf(fp, "%.1lf\t%.1lf\t%d", center[1].pos_x(), center[1].pos_y(), 2);

	fclose(fp);
}

/*****************************************
Copyright (c) 2015 Jingshuang Hu

@filename:clas_point.h
@datetime:2015.11.16
@author:HJS
@e-mail:jingshuang_hu@163.com
@blog:http://blog.csdn.net/hujingshuang
*****************************************/
#ifndef _CLASS_POINT_H_
#define _CLASS_POINT_H_

#include <iostream>

using namespace std;

class Point
{
public:
	Point();
	Point(Point &);					//拷贝构造函数
	double pos_x(void);				//获取x坐标
	double pos_y(void);				//获取y坐标
	int pos_label(void);			//获取样本点标签
	void set_cursor(double, double);//设置坐标
	void set_label(int);			//设置标签
private:
	int label;						//标签
	double x;						//横坐标
	double y;						//纵坐标
};

#endif

/*****************************************
Copyright (c) 2015 Jingshuang Hu

@filename:class_point.cpp
@datetime:2015.11.16
@author:HJS
@e-mail:jingshuang_hu@163.com
@blog:http://blog.csdn.net/hujingshuang
*****************************************/
#include "class_point.h"

Point::Point()
{}
Point::Point(Point &point)	//拷贝构造函数
{
	x = point.x;
	y = point.y;
	label = point.label;
}
double Point::pos_x(void)
{
	return x;
}
double Point::pos_y(void)
{
	return y;
}
int Point::pos_label(void)
{
	return label;
}
void Point::set_cursor(double x = 0, double y = 0)
{
	this->x = x;
	this->y = y;
}
void Point::set_label(int label = 0)
{
	this->label = label;
}

K-means聚类

原文：http://blog.csdn.net/hujingshuang/article/details/49867455