Use class to keep track of average lane lines

python-class.py

class Lane():
    def __init__(self):
        #everything starting with `self` keyword will be consider property/data memeber/field of this class
        #here we declare all the fields/variables of this class that we need to keep track of data
        
        #flag to represent whether first polynomial fitting has been done
        #and now that data can be used for future
        self.is_ready = False
        #fitting done on current frame
        self.current_fit = None
        #fitting in meters per pixel
        self.current_fit_m = None
        #current curvature
        self.current_curvature = None
        #all curvatures
        self.all_curvatures = []
        #all fits
        self.all_fits = []
        #all fits_m
        self.all_fits_m = []
        
        #Iterations count to take avg 
        self.N = 10
        
    def add_fit(self, fit):
        self.current_fit = None
        self.all_fits.append(fit)
        self.is_ready = True
        
    def avg_fit(self):
        n_fits = self.all_fits[-self.N:]
        
        if(len(self.all_fits_m) > self.N):
            self.all_fits = n_fits
        
        return np.mean(np.array(n_fits), axis=0)

#--------------Below code is outside of class. Remember, the indentation of this code is not under class but at the same
# level as class
#declaring Lane objects for left_lane and right lane
left_lane = Lane()
right_lane = Lane()

#for image : images/video
    #left_fit = fit the left line
    #left_lane.add_fit(left_fit)

    #right_fit = fit the right line
    #right_lane.add_fit(right_fit)
    
    #now use average fit to draw on image, something like this
    #drawn_img(undistorted_img, warped_binary, left_lane.avg_fit(), right_lane.avg_fit())