Sorting Contours Left To Right In Python (opencv)

I'm using Python and OpenCV to detect contours in my image. But when I run the following code to draw only a specific contour using the contour index, since the indices allocated a

Solution 1:

Implements de sort function of list in python like here.

In the implemented function you calculate the center and verify if the X position is gretter or smaller them the other. If gretter return 1, smaller -1 and equals 0.

def greater(a, b):
    momA = cv2.moments(a)        
    (xa,ya) = int(momA['m10']/momA['m00']), int(momA['m01']/momA['m00'])

    momB = cv2.moments(b)        
    (xb,yb) = int(momB['m10']/momB['m00']), int(momB['m01']/momB['m00'])
    if xa > xb:
        return1ifxa== xb:
        return0elsereturn -1

For sure you can do better if you calculate the centers only once.

then just do

contours.sort(greater)