K-means算法是很典型的基于距离的聚类算法,采用距离作为相似性的评价指标,即认为两个对象的距离越近,其相似度就越大。该算法认为簇是由距离靠近的对象组成的,因此把得到紧凑且独立的簇作为最终目标。
算法过程如下:
1)从N个样本随机选取K个样本作为质心
2)对剩余的每个样本测量其到每个质心的距离,并把它归到最近的质心的类
3)重新计算已经得到的各个类的质心
4)迭代2~3步直至新的质心与原质心相等或小于指定阈值,算法结束
#include<stdio.h> #include<stdlib.h> #include<string.h> #include<time.h> #include<math.h> #define DIMENSIOM 2 //目前只是处理2维的数据 #define MAX_ROUND_TIME 100 //最大的聚类次数 typedef struct Item{
int dimension_1;
//用于存放第一维的数据 int dimension_2;
//用于存放第二维的数据 int clusterID;
//用于存放该item的cluster center是谁 }
Item;
Item* data;
typedef struct ClusterCenter{
double dimension_1;
double dimension_2;
int clusterID;
}
ClusterCenter;
ClusterCenter* cluster_center_new;
int isContinue;
int* cluster_center;
//记录center double* distanceFromCenter;
//记录一个“点”到所有center的距离 int data_size;
char filename[200];
int cluster_count;
void initial();
void readDataFromFile();
void initial_cluster();
void calculateDistance_ToOneCenter(int itemID, int centerID, int count);
void calculateDistance_ToAllCenter(int itemID);
void partition_forOneItem(int itemID);
void partition_forAllItem_OneCluster(int round);
void calculate_clusterCenter(int round);
void K_means();
void writeClusterDataToFile(int round);
void writeClusterCenterToFile(int round);
void compareNew_OldClusterCenter(double* new_X_Y);
void test_1();
int main(int argc, char* argv[]){
if( argc != 4 ) {
printf("This application need other parameter to run:" "nttthe first is the size of data set," "nttthe second is the file name that contain data" "nttthe third indicate the cluster_count" "n");
exit(0);
}
srand((unsigned)time(NULL));
data_size = atoi(argv[1]);
strcat(filename, argv[2]);
cluster_count = atoi(argv[3]);
initial();
readDataFromFile();
initial_cluster();
//test_1();
//partition_forAllItem_OneCluster();
//calculate_clusterCenter();
K_means();
return 0;
}
/* * 对涉及到的二维动态数组根据main函数中传入的参数分配空间 * */ void initial(){
data = (Item*)malloc(sizeof(struct Item) * (data_size + 1));
if( !data ) {
printf("malloc error:data!");
exit(0);
}
cluster_center = (int*)malloc(sizeof(int) * (cluster_count + 1));
if( !cluster_center ) {
printf("malloc error:cluster_center!n");
exit(0);
}
distanceFromCenter = (double*)malloc(sizeof(double) * (cluster_count + 1));
if( !distanceFromCenter ) {
printf("malloc error: distanceFromCenter!n");
exit(0);
}
cluster_center_new = (ClusterCenter*)malloc(sizeof(struct ClusterCenter) * (cluster_count + 1));
if( !cluster_center_new ) {
printf("malloc cluster center new error!n");
exit(0);
}
}
/* * 从文件中读入x和y数据 * */ void readDataFromFile(){
FILE* fread;
if( NULL == (fread = fopen(filename, "r"))) {
printf("open file(%s) error!n", filename);
exit(0);
}
int row;
for( row = 1;
row <= data_size;
row++ ) {
if( 2 != fscanf(fread, "%d %d ", &data[row].dimension_1, &data[row].dimension_2)) {
printf("fscanf error: %dn", row);
}
data[row].clusterID = 0;
}
}
/* * 根据从主函数中传入的@cluster_count(聚类的个数)来随机的选择@cluster_count个 * 初始的聚类的起点 * */ void initial_cluster(){
//辅助产生不重复的数 int* auxiliary;
int i;
auxiliary = (int*)malloc(sizeof(int) * (data_size + 1));
if( !auxiliary ) {
printf("malloc error: auxiliary");
exit(0);
}
for( i = 1;
i <= data_size;
i++ ) {
auxiliary[i] = i;
}
//产生初始化的cluster_count个聚类 int length = data_size;
int random;
for( i = 1;
i <= cluster_count;
i++ ) {
random = rand()%length + 1;
//printf("%d n", auxiliary[random]);
//data[auxiliary[random]].clusterID = auxiliary[random];
cluster_center[i] = auxiliary[random];
auxiliary[random] = auxiliary[length--];
}
for( i = 1;
i <= cluster_count;
i++ ) {
cluster_center_new[i].dimension_1 = data[cluster_center[i]].dimension_1;
cluster_center_new[i].dimension_2 = data[cluster_center[i]].dimension_2;
cluster_center_new[i].clusterID = i;
data[cluster_center[i]].clusterID = i;
}
}
/* * 计算一个点(还没有划分到cluster center的点)到一个cluster center的distance * @itemID: 不属于任何cluster中的点 * @centerID: center的ID * @count: 表明在计算的是itemID到第几个@center的distance,并且指明了结果放在distanceFromCenter的第几号元素 * */ void calculateDistance_ToOneCenter(int itemID,int centerID){
distanceFromCenter[centerID] = sqrt( (data[itemID].dimension_1-cluster_center_new[centerID].dimension_1)*(double)(data[itemID].dimension_1-cluster_center_new[centerID].dimension_1) + (double)(data[itemID].dimension_2-cluster_center_new[centerID].dimension_2) * (data[itemID].dimension_2-cluster_center_new[centerID].dimension_2) );
}
/* * 计算一个点(还没有划分到cluster center的点)到每个cluster center的distance * */ void calculateDistance_ToAllCenter(int itemID){
int i;
for( i = 1;
i <= cluster_count;
i++ ) {
calculateDistance_ToOneCenter(itemID, i);
}
}
void test_1() {
calculateDistance_ToAllCenter(3);
int i;
for( i = 1;
i <= cluster_count;
i++ ) {
printf("%f ", distanceFromCenter[i]);
}
}
/* * 在得到任一的点(不属于任一cluster的)到每一个cluster center的distance之后,决定它属于哪一个cluster center,即取距离最小的 * 函数功能:得到一个item所属的cluster center * */ void partition_forOneItem(int itemID){
//操作对象是 distanceFromCenter和cluster_center int i;
int min_index = 1;
double min_value = distanceFromCenter[1];
for( i = 2;
i <= cluster_count;
i++ ) {
if( distanceFromCenter[i] < min_value ) {
min_value = distanceFromCenter[i];
min_index = i;
}
}
data[itemID].clusterID = cluster_center_new[min_index].clusterID;
}
/* * 得到所有的item所属于的cluster center , 在一轮的聚类中 * */ void partition_forAllItem_OneCluster(int round){
//changed!!!!!!!!!!!!!!!!!!!!!!!! int i;
for( i = 1;
i <= data_size;
i++ ) {
if( data[i].clusterID != 0 ) continue;
else {
calculateDistance_ToAllCenter(i);
//计算i到所有center的distance partition_forOneItem(i);
//根据distance对i进行partition }
}
//把聚类得到的数据写入到文件中 writeClusterDataToFile(round);
}
/* * 将聚类得到的数据写入到文件中,每一个类写入一个文件中 * @round: 表明在进行第几轮的cluster,该参数的另一个作用是指定了文件名字中的第一个项. * */ void writeClusterDataToFile(int round){
int i;
char filename[200];
FILE** file;
file = (FILE**)malloc(sizeof(FILE*) * (cluster_count + 1));
if( !file ) {
printf("malloc file error!n");
exit(0);
}
for( i = 1;
i <= cluster_count;
i++ ) {
sprintf(filename, ".//ClusterProcess//round%d_cluster%d.data", round, i);
if( NULL == (file[i] = fopen(filename, "w"))) {
printf("file open(%s) error!", filename);
exit(0);
}
}
for( i = 1;
i <= data_size;
i++ ) {
//sprintf(filename, ".//ClusterProcess//round%d_cluster%d.data", round, data[i].clusterID);
fprintf(file[data[i].clusterID], "%dt%dn", data[i].dimension_1, data[i].dimension_2);
}
for( i = 1;
i <= cluster_count;
i++ ) {
//sprintf(filename, ".//ClusterProcess//round%d_cluster%d.data", round, i);
fclose(file[i]);
}
}
/* * 重新计算新的cluster center * */ void calculate_clusterCenter(int round){
//changed!!!!!!!!!!!!!!!!!!!!!! int i;
double* new_X_Y;
/* 用来计算和保存新的cluster center的值,同样的,0号元素不用。1,2号元素分别用来 存放第一个聚类的所有的项的x和y的累加和。3,4号元素分别用来存放第二个聚类的所有 的项的x和y的累加和...... */ new_X_Y = (double*)malloc(sizeof(double) * (2 * cluster_count + 1));
if( !new_X_Y ) {
printf("malloc error: new_X_Y!n");
exit(0);
}
//初始化为0 for( i = 1;
i <= 2*cluster_count;
i++ ) new_X_Y[i] = 0.0;
//用来统计属于各个cluster的item的个数 int* counter;
counter = (int*)malloc(sizeof(int) * (cluster_count + 1));
if( !counter ) {
printf("malloc error: countern");
exit(0);
}
//初始化为0 for( i = 1;
i <= cluster_count;
i++ ) counter[i] = 0;
for( i = 1;
i <= data_size;
i++ ) {
new_X_Y[data[i].clusterID * 2 - 1] += data[i].dimension_1;
new_X_Y[data[i].clusterID * 2] += data[i].dimension_2;
counter[data[i].clusterID]++;
}
for( i = 1;
i <= cluster_count;
i++ ) {
new_X_Y[2 * i - 1] = new_X_Y[2 * i - 1] / (double)(counter[i]);
new_X_Y[2 * i] = new_X_Y[2 * i] / (double)(counter[i]);
}
//要将cluster center的值保存在文件中,后续作图 writeClusterCenterToFile(round);
/* * 在这里比较一下新的和旧的cluster center值的差别。如果是相等的,则停止K-means算法。 * */ compareNew_OldClusterCenter(new_X_Y);
//将新的cluster center的值放入cluster_center_new for( i = 1;
i <= cluster_count;
i++ ) {
cluster_center_new[i].dimension_1 = new_X_Y[2 * i - 1];
cluster_center_new[i].dimension_2 = new_X_Y[2 * i];
cluster_center_new[i].clusterID = i;
}
free(new_X_Y);
free(counter);
//在重新计算了新的cluster center之后,意味着我们要重新来为每一个Item进行聚类,所以data中用于表示聚类ID的clusterID //要都重新置为0。 for( i = 1;
i <= data_size;
i++ ) {
data[i].clusterID = 0;
}
}
/* * 将得到的新的cluster_count个cluster center的值保存在文件中。以便于观察聚类的过程。 * */ void writeClusterCenterToFile(int round){
FILE* file;
int i;
char filename[200];
sprintf(filename, ".//ClusterProcess//round%d_clusterCenter.data", round);
if( NULL == (file = fopen(filename, "w"))) {
printf("open file(%s) error!n", filename);
exit(0);
}
for( i = 1;
i <= cluster_count;
i++ ) {
fprintf(file, "%ft%fn", cluster_center_new[i].dimension_1, cluster_center_new[i].dimension_2);
}
for( i = 1;
i <= cluster_count;
i++ ) {
fclose(file);
}
}
/* * 比较新旧的cluster center的差异 * */ void compareNew_OldClusterCenter(double* new_X_Y){
int i;
isContinue = 0;
//等于0表示的是不要继续 for( i = 1;
i <= cluster_count;
i++ ) {
if( new_X_Y[2 * i - 1] != cluster_center_new[i].dimension_1 || new_X_Y[2 * i] != cluster_center_new[i].dimension_2) {
isContinue = 1;
//要继续 break;
}
}
}
/************************************************************************************************ * K-means算法 * ***********************************************************************************************/ void K_means(){
int times_cluster;
for( times_cluster = 1;
times_cluster <= MAX_ROUND_TIME;
times_cluster++ ) {
printf("n times : %d n", times_cluster);
partition_forAllItem_OneCluster(times_cluster);
calculate_clusterCenter(times_cluster);
if( 0 == isContinue ) {
break;
//printf("nnthe application can stop!nn");
}
}
}
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