def box_size_calculate(r):
  """ Calculates 1D size of bounding box
      Args:
        r:
          A list containing the 2 co-ordinates of image [(x1, y1), (x2, y2)]
      Returns:
      	length and width of box
  """
  length = r[2] - r[0]
  width = r[3] - r[1]
  return length, width