cvseqpartition序列分類

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

也可參考，於詩琪老師的書。。

#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; //聲明輸出標籤
double threshold = pos*pos; //定義閾值爲pos^2
int i, class_count = cvSeqPartition( point_seq, 0,&labels, is_equal, &threshold);
//對point_seq點序列拆分爲等效的類，條件是(Ax-Bx)^2+(Ay-By)^2<=pos^2
//含義爲兩點相差距離小於pos的屬於一類
printf("%4d classesn", class_count );
//打印出分了幾類
cvZero( canvas );

for( i = 0; i <labels->total; i++ )
{//取點、取顏色，畫圓,你可以用按任意鍵的方式一個點一個點的畫
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);//建立了一個存儲器
point_seq = cvCreateSeq( CV_32SC2, sizeof(CvSeq), sizeof(CvPoint),storage );
//建立了一個32位整型序列
CvRNG rng = cvRNG(0xffffffff);//初始化隨機數生成器

int width = 500, height = 500;//定義圖像的長和寬
int i, count = 1000;//定義了兩個計數器
canvas = cvCreateImage( cvSize(width,height), 8, 3 );
//設置圖像，大小爲500*500，色深8，三通道

colors = (CvScalar*)cvAlloc( count*sizeof(colors[0]));
//分配1000個CvScalar大小的內存緩衝區
for( i = 0; i < count; i++ )
{
CvPoint pt;//設置一個點
int icolor;//定義顏色標的
pt.x = cvRandInt( &rng ) % width;//隨機產生點的x座標
pt.y = cvRandInt( &rng ) % height;//隨機產生點的y座標
cvSeqPush( point_seq, &pt );//添加這個點到序列的尾部
icolor = cvRandInt( &rng ) +0xa0a0a0a0 ;
//用隨機的方法給顏色標的一個基準，後邊加的那個數字是可以任意的。
colors[i] = CV_RGB(icolor & 255, (icolor>> 8)&255, (icolor>> 16)&255);
//把這個點的顏色完全寫入標量容器colors中
}

cvNamedWindow( "points", 1 );//創建窗口
cvCreateTrackbar( "threshold", "points", &pos, 50,on_track );
//建立拖動條，名稱爲threshold，窗口的名字叫points，創建初始化值取自pos，
//回調函數名稱爲on_track
on_track(pos);//監視拖動條的改變並處理之
cvWaitKey(0);
return 0;
}