VectorClass.py

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# Sprite Movement Towards Target Example
# programed/documented by Mad Cloud Games
# contact Mad Cloud Games @ madcloudgames@gmail.com with any comments, questions, or changes
#
# This project is released under the GNU General Public License V3
# This code is open source
# We would love to know what it gets used for
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import pygame, math
from pygame.locals import *

class Vector():
    '''
        Class:
            creates operations to handle vectors such
            as direction, position, and speed
        '''
    def __init__(self, x, y):
        self.x = x
        self.y = y

    def __str__(self): # used for printing vectors
        return "(%s, %s)"%(self.x, self.y)

    def __getitem__(self, key):
        if key == 0:
            return self.x
        elif key == 1:
            return self.y
        else:
            raise IndexError("This "+str(key)+" key is not a vector key!")

    def __sub__(self, o): # subtraction
        return Vector(self.x - o.x, self.y - o.y)

    def length(self): # get length (used for normalize)
        return math.sqrt((self.x**2 + self.y**2)) 

    def normalize(self): # divides a vector by its length
        l = self.length()
        if l != 0:
            return (self.x / l, self.y / l)
        return None