UnboundLocalError:赋值前引用的局部变量“coordi”

Question

下面是一个python函数，用于检测对象并返回其边界框坐标：

def back_project_dilation(hist1,hist2,hsv,min_area,max_area,min_aspect,max_aspect,min_rect,max_rect):

 Ratio=hist1/hist2
 
 #calculating the M_blue
 #spliting the target channels
 h,s,v = cv2.split(hsv)

 #backprojecting the R_red hist
 B = Ratio[h.ravel(),s.ravel()]
 B = np.minimum(B,1)
 B = B.reshape(hsv_1.shape[:2])
 B[B >0 ]+=1
 B = np.minimum(B,1) 
 Open=cv2.morphologyEx(B,cv2.MORPH_OPEN,kernel)
 dilation = cv2.dilate(Open,kernel,iterations = 2)
 #dilation_special=dilation_special.astype(np.uint8)
 dilation*= 255
 dilation=dilation.astype(np.uint8)
 
 contours =cv2.findContours(dilation, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
 cntss = imutils.grab_contours(contours)
 if len(cntss) > 0:
   

  # print('ture')
   for cr in cntss:
                 
                 area=cv2.contourArea(cr)
                 
                 (x,y,w,h)=cv2.boundingRect(cr)
                 
                 aspect=w/float(h)
                                                        
                 if area>=min_area and area<=max_area and aspect>=min_aspect and aspect<=max_aspect:
                     center, (width,height),_=cv2.minAreaRect(cr)
                     rect=area/float((width*height))
                    
                     if rect>=min_rect and rect<=max_rect:
                           
                           
                           
                          
                        coordi = cv2.boundingRect(cr)
 return coordi

函数内部使用的检测方法称为“直方图反投影”

该函数在while循环中被调用四次，因为该函数用于同时检测两个视频中的小型汽车

while True: 
  
ret1,frame1=cap1.read()
ret2,frame2=cap2.read()
cv2.imwrite('image22.jpg',frame1)
if ret1 and ret2 !=True:
    print('cannot open Videos, please cheack your source')
    break
else:
 hsv_1 = cv2.cvtColor(frame1, cv2.COLOR_BGR2HSV)
 hsv_hist_1 = cv2.calcHist([hsv_1.copy()],[0,1],None,[180,256],[0,180,0,256])
 
 hsv_2 = cv2.cvtColor(frame2, cv2.COLOR_BGR2HSV)
 hsv_hist_2 = cv2.calcHist([hsv_2.copy()],[0,1],None,[180,256],[0,180,0,256])
 

 B_red_coord=back_project_dilation(hist_red,hsv_hist_1,hsv_1,619,1090,1.2432432432432432,3.0588235294117645,0.7296458280876743,1)

 B_red_2_coord = back_project_dilation(hist_red,hsv_hist_2,hsv_2,619,1090,1.2432432432432432,3.0588235294117645,0.7296458280876743,1)
 

 B_blue_coord  = back_project_dilation(hist_blue,hsv_hist_1,hsv_1,522,903,0.875,2.68,0.76504332843943325,1.000000410476877)
 B_blue_2_coord  = back_project_dilation(hist_blue,hsv_hist_2,hsv_2,522,903,0.875,2.68,0.76504332843943325,1.000000410476877) 

因此，当函数调用4次时，我应该获得4个输出（这是两个视频中两辆车的质心坐标）

运行代码时，出现以下错误：

<module>
B_red_2_coord = back_project_dilation(hist_red,hsv_hist_2,hsv_2,619,1090,1.2432432432432432,3.0588235294117645,0.7296458280876743,1)

back_project_dilation
return coordi

UnboundLocalError: local variable 'coordi' referenced before assignment

我在stack overflow中查找了这个问题，发现了类似的问题，但是我不知道如何针对我的问题提出建议的解决方案

因此，我将感谢一些帮助和提前感谢

哈立德·杰巴利

Answer 1

我通过将变量“coordi”设置为global解决了这个问题