cvseqpartition序列分类

转自：http://www.cnblogs.com/gnuhpc/archive/2012/10/09/2717306.html

也可参考，于诗琪老师的书。。

#include "cxcore.h"
#include "highgui.h"
#include <stdio.h>

CvSeq* point_seq = 0;
IplImage* canvas = 0;
CvScalar* colors = 0;
int pos = 10;

int is_equal( const void* _a, const void* _b, void*userdata )
{
CvPoint a = *(const CvPoint*)_a;
CvPoint b = *(const CvPoint*)_b;
double threshold = *(double*)userdata;
return (double)(a.x - b.x)*(a.x - b.x) + (double)(a.y - b.y)*(a.y -b.y) <= threshold;
}

void on_track( int pos )
{
CvSeq* labels = 0; //声明输出标签
double threshold = pos*pos; //定义阈值为pos^2
int i, class_count = cvSeqPartition( point_seq, 0,&labels, is_equal, &threshold);
//对point_seq点序列拆分为等效的类，条件是(Ax-Bx)^2+(Ay-By)^2<=pos^2
//含义为两点相差距离小于pos的属于一类
printf("%4d classesn", class_count );
//打印出分了几类
cvZero( canvas );

for( i = 0; i <labels->total; i++ )
{//取点、取颜色，画圆,你可以用按任意键的方式一个点一个点的画
CvPoint pt = *(CvPoint*)cvGetSeqElem( point_seq, i );
CvScalar color = colors[*(int*)cvGetSeqElem( labels, i )];
cvCircle( canvas, pt, 1, color, -1 );
cvShowImage( "points", canvas );
cvWaitKey(0);
}

}

int main( int argc, char** argv )
{
CvMemStorage* storage = cvCreateMemStorage(0);//建立了一个存储器
point_seq = cvCreateSeq( CV_32SC2, sizeof(CvSeq), sizeof(CvPoint),storage );
//建立了一个32位整型序列
CvRNG rng = cvRNG(0xffffffff);//初始化随机数生成器

int width = 500, height = 500;//定义图像的长和宽
int i, count = 1000;//定义了两个计数器
canvas = cvCreateImage( cvSize(width,height), 8, 3 );
//设置图像，大小为500*500，色深8，三通道

colors = (CvScalar*)cvAlloc( count*sizeof(colors[0]));
//分配1000个CvScalar大小的内存缓冲区
for( i = 0; i < count; i++ )
{
CvPoint pt;//设置一个点
int icolor;//定义颜色标的
pt.x = cvRandInt( &rng ) % width;//随机产生点的x座标
pt.y = cvRandInt( &rng ) % height;//随机产生点的y座标
cvSeqPush( point_seq, &pt );//添加这个点到序列的尾部
icolor = cvRandInt( &rng ) +0xa0a0a0a0 ;
//用随机的方法给颜色标的一个基准，后边加的那个数字是可以任意的。
colors[i] = CV_RGB(icolor & 255, (icolor>> 8)&255, (icolor>> 16)&255);
//把这个点的颜色完全写入标量容器colors中
}

cvNamedWindow( "points", 1 );//创建窗口
cvCreateTrackbar( "threshold", "points", &pos, 50,on_track );
//建立拖动条，名称为threshold，窗口的名字叫points，创建初始化值取自pos，
//回调函数名称为on_track
on_track(pos);//监视拖动条的改变并处理之
cvWaitKey(0);
return 0;
}