Title: 2d Vector ClassAuthor: Chris Wood (http://grace.2ya.com) Description: A simple 2d vector class Download: vector.py pygame version required: None Comments: Here's a small class that provides the basics of 2d vector math. Adding other functions like vector multiplication and dot product calculation should be simple if you follow the outline of this class. 
""" vector.py A simple physics 2D vector class Licence: Public Domain Author: Chris Wood (http://grace.2ya.com) 20 September 2002 Any game involving 2D physics could do with a class similar to this one. This class is as fast as possible while still providing all the functionality you would commonly need. Note that storing the vector as cartesian coordinates (rather than polar or both) makes for faster for vector addition. It is assumed that you won't often need the polar coordinates. """ from math import sin, cos, atan, hypot # The quick way to know how big the pie is PI = 3.141592653589793238462643383 TwoPI = PI * 2.0 HalfPI = PI * 0.5 OneAndHalfPI = PI * 1.5 # new math function def direction(x, y): """Return the direction component of a vector (in radians), given cartesian coordinates. """ if x > 0: if y >= 0: return atan(y / x) else: return atan(y / x) + TwoPI elif x == 0: if y > 0: return HalfPI elif y == 0: return 0 else: return OneAndHalfPI else: return atan(y / x) + PI class Vector: """Store a vector in cartesian coordinates.""" def __init__(self, f = 0.0, mag = 0.0): """Create a Vector, given polar coordinates.""" # Calculate cartesian coordinates self.x = mag * cos(f) self.y = mag * sin(f) def add(self, b): """Add b to self, where b is another Vector.""" self.x += b.x self.y += b.y def heading(self): """Return the direction of the Vector in radians.""" return direction(self.x, self.y) def mag(self): """Return the magnitude of the Vector.""" return hypot(self.x, self.y)
From: Dave Beach 
Date: January 31, 2004 17:17 GMT 
This class could be made faster for Python 2.3 with the following small changes:

From: Anonymous 
Date: February 26, 2004 12:11 GMT 
( from quickreference site )

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