Polygon approximation for a contour segement with a given number of sides

gistfile1.txt

def fixedPoly(contour, polysides = 8):
    opencv_contour = contour.reshape(-1, 1, 2)
    
    higherr = 50.0
    lowerr = 1.0
    tryerr = 25.0
    poly = []
    #binary search polygon approximations until we get a 4 point polygon
    maxiterations = 100
    while len(poly) != polysides and maxiterations:
        poly = cv2.approxPolyDP(opencv_contour, tryerr, False)
        maxiterations -= 1
        
        
        if len(poly) < polysides:
            higherr = tryerr
            tryerr = (higherr + lowerr) / 2
        
        if len(poly) > polysides:
            lowerr = tryerr
            tryerr = (higherr + lowerr) / 2
    
            
    poly = poly.reshape(-1, 2)  # get it out of opencv 
    return poly

this is probably backwards -- i imagine this can be much more efficiently done, but it works for me