Class Line

numericals.py:147–311

Numerical line.

class Line:
  """Numerical line."""

  def __init__(
      self,
      p1: Point = None,
      p2: Point = None,
      coefficients: tuple[int, int, int] = None,
  ):
    if p1 is None and p2 is None and coefficients is None:
      self.coefficients = None, None, None
      return

    a, b, c = coefficients or (
        p1.y - p2.y,
        p2.x - p1.x,
        p1.x * p2.y - p2.x * p1.y,
    )

    # Make sure a is always positive (or always negative for that matter)
    # With a == 0, Assuming a = +epsilon > 0
    # Then b such that ax + by = 0 with y>0 should be negative.
    if a < 0.0 or a == 0.0 and b > 0.0:
      a, b, c = -a, -b, -c

    self.coefficients = a, b, c

  def parallel_line(self, p: Point) -> Line:
    a, b, _ = self.coefficients
    return Line(coefficients=(a, b, -a * p.x - b * p.y))  # pylint: disable=invalid-unary-operand-type

  def perpendicular_line(self, p: Point) -> Line:
    a, b, _ = self.coefficients
    return Line(p, p + Point(a, b))

  def greater_than(self, other: Line) -> bool:
    a, b, _ = self.coefficients
    x, y, _ = other.coefficients
    # b/a > y/x
    return b * x > a * y

  def __gt__(self, other: Line) -> bool:
    return self.greater_than(other)

  def __lt__(self, other: Line) -> bool:
    return other.greater_than(self)

  def same(self, other: Line) -> bool:
    a, b, c = self.coefficients
    x, y, z = other.coefficients
    return close_enough(a * y, b * x) and close_enough(b * z, c * y)

  def equal(self, other: Line) -> bool:
    a, b, _ = self.coefficients
    x, y, _ = other.coefficients
    # b/a == y/x
    return b * x == a * y