python中的IF语法错误

Question

我在if语法中有错误

if(m.distance<0.75*n.distance):

• 我正在进行图像处理项目

代码：

while True:

    ret, QueryImgBGR=cam.read()
    QueryImg=cv2.cvtColor(QueryImgBGR,cv2.COLOR_BGR2GRAY)
    queryKP,queryDesc=detector.detectAndCompute(QueryImg,None)
    matches=flann.knnMatch(queryDesc,trainDesc,k=2)
    goodMatch=[]

    for m,n in matches:
         if(m.distance<0.75*n.distance):
             goodMatch.append(m)

    if(len(goodMatch)>MIN_MATCH_COUNT):
        tp=[]
        qp=[]

        for m in goodMatch:
            tp.append(trainKP[m.trainIdx].pt)
            qp.append(queryKP[m.queryIdx].pt)
        tp,qp=np.float32((tp,qp))
        H,status=cv2.findHomography(tp,qp,cv2.RANSAC,3.0)
        h,w=trainImg.shape
        trainBorder=np.float32([[[0,0],[0,h-1],[w-1,h-1],[w-1,0]]])
        queryBorder=cv2.perspectiveTransform(trainBorder,H)
        cv2.polylines(QueryImgBGR,[np.int32(queryBorder)],True,(0,255,0),5)
    else:
        print "Not Enough match found- %d/%d"%(len(goodMatch),MIN_MATCH_COUNT)

    cv2.imshow('result',QueryImgBGR)
    if cv2.waitKey(10)==ord('q'):
        break

cam.release()
cv2.destroyAllWindows()   

Answer 1

半冒号用于终止语句，当if语句中存在语句时终止语句。它通常用于在同一行上编写多个语句，如a=1;print a;c=3;