无法将设置分配给变量python

Question

嗨，我想知道这是否可能，因为我试过了，但我的变量总是空的。在我的项目中，我通过树莓派上的 PiCamera 跟踪静态对象和激光指示器，并将它们的轮廓的质心分别计算为 (smallx,smally) 和 (small2x,small2y)。

我使用它们坐标之间的差异来查看指针是否应该向上、向下、向左或向右移动，以便与第一个静态对象相遇。之后，它会选择 1 到 4 之间的方向移动，因为我的方向控件在 x-y 轴上并不完美并且是倾斜的。

我留下了从这里查找的控件和轮廓，并缩短了我的总代码，这样你就不会遇到一大堆垃圾来整理。

编辑：根据我的理解，我不认为我可以在不发布几百行代码和我的小设备的情况下提供可运行的东西，但我会把它归结为相关的代码的确切部分。运行 Python 2.7.3，使用 opencv2.4.10

代码：

#import libraries like picamera and opencv
#set empty variables like:
up = down = left = right = set()
smallx = smally = small2x = small2y = 0
#etc etc

with picamera.PiCamera() as camera:
    with picamera.array.PiRGBArray(camera) as rawCapture:

    #Calibrate my controls with the camera. updates the up, down, left, and right sets.


with picamera.PiCamera() as camera:
    with picamera.array.PiRGBArray(camera) as rawCapture:

    # Take pictures, threshold them, find contours, append their arrays to list

    if len(cnts)>0:     #If any objects were identified
            contm = sorted(smalList, key=lambda tup: tup[1])
            smallest = cnts[smalList[0][0]]           #**Take smallest object(my static object)**

            smallM = cv2.moments(smallest)                      
            smallx = int(smallM['m10']/smallM['m00'])  #**Calculate xcoord**   
            smally = int(smallM['m01']/smallM['m00'])  #**Calculate ycoord**

            cv2.line(frame, (smallx,smally), (smallx,smally), 1, 8,0) #Draws centroid

            # print(len(cnts))

            if len(cnts)==2:        #If only 2 objects were identified
                smallester = cnts[smalList[1][0]]      #** Take pointer object **
                small2 = cv2.moments(smallester)                        
                small2x = int(small2['m10']/small2['m00']) #**Calculate xcoord**
                small2y = int(small2['m01']/small2['m00']) #**Calculate ycoord**

                x = small2x - smallx
                y = small2y - smally

                print x #These prints return a value
                print y


                if x < 0:                       #Difference = Pointer - Object
                    s1 = right

                if x >0:
                    s1 = left

                if y < 0:
                    s2 = down
                if y >0:
                    s2 = up
                print s1, s2                  #set([]),set([])
                print up,down,left,right      #set([1,2]),set([3,4]),set([1,4]),set([2,3])

                selecty = s1&s2               #set([])


    #Tell the pointer where to go

我什至应该使用集合吗？

Answer 1

使用s1 = s2 = set() 代替= 0。

至于您的第二个问题，可能有更好和更知名的方法来解决您的问题。例如，使用位逻辑：

right = 1
up = 2
left = 4
down = 8

select = 0


if (small2x - smallx) < 0:  
    select |= right
if (small2x - smallx) >0:
    select |= left

if (small2y - smally) < 0:
    select |= down
if (small2y - smally) >0:
    select |= up

print(select)
print("You chose %s%s%s%s" %("UP " if select & up else "",
                             "DOWN " if select & down else "", 
                             "LEFT " if select & left else "",
                             "RIGHT" if select & right else ""))


#Do things after