vector2.py

#!/usr/bin/python
# coding: latin-1

import math

class Vector2(object):

    def __init__(self, x=0.0, y=0.0):
        self.x = x
        self.y = y

    def __str__(self):
        return "(%s, %s)"%(self.x, self.y)

    def _get_length(self):
        x, y = self.x, self.y
        return sqrt(x*x + y*y)
    
    def _set_length(self, length):
        try:
            x, y = self.x, self.y
            l = length / sqrt(x*x +y*y)
        except ZeroDivisionError:
            v[0] = 0.0
            v[1] = 0.0
            return self
        v[0] *= l
        v[1] *= l
    length = property(_get_length, _set_length, None, "Length of the vector")

    @staticmethod
    def from_points(P1, P2):
        return Vector2(P2[0] - P1[0], P2[1] - P1[1])

    def get_magnitude(self):
        return math.sqrt( self.x**2 + self.y**2 )

    def normalize(self):
        magnitude = self.get_magnitude()

        try:
            self.x /= magnitude
            self.y /= magnitude
        except ZeroDivisionError:
            self.x = 0
            self.y = 0

    # rhs stands for Right Hand Side
    def __add__(self, rhs):
        return Vector2(self.x + rhs.x, self.y + rhs.y)

    def __sub__(self, rhs):
        return Vector2(self.x - rhs.x, self.y - rhs.y)

    def __neg__(self):
        return Vector2(-self.x , -self.y)

    def __mul__(self, scalar):
        return Vector2(self.x * scalar, self.y * scalar)

    def __div__(self, scalar):
        return Vector2(self.x / scalar, self.y / scalar)