class Vec: | |
""" A simple vector class | |
Instances of the Vec class can be constructed from numbers | |
>>> a = Vec(1, 2, 3) | |
>>> b = Vec(3, 2, 1) | |
added | |
>>> a + b | |
Vec(4, 4, 4) | |
subtracted | |
>>> a - b | |
Vec(-2, 0, 2) | |
and multiplied by a scalar on the left | |
>>> 3.0 * a | |
Vec(3.0, 6.0, 9.0) | |
or on the right | |
>>> a * 3.0 | |
Vec(3.0, 6.0, 9.0) | |
""" | |
def __init__(self, *v): | |
self.v = list(v) | |
@classmethod | |
def fromlist(cls, v): | |
if not isinstance(v, list): | |
raise TypeError | |
inst = cls() | |
inst.v = v | |
return inst | |
def __repr__(self): | |
args = ', '.join(repr(x) for x in self.v) | |
return 'Vec({0})'.format(args) | |
def __len__(self): | |
return len(self.v) | |
def __getitem__(self, i): | |
return self.v[i] | |
def __add__(self, other): | |
# Element-wise addition | |
v = [x + y for x, y in zip(self.v, other.v)] | |
return Vec.fromlist(v) | |
def __sub__(self, other): | |
# Element-wise subtraction | |
v = [x - y for x, y in zip(self.v, other.v)] | |
return Vec.fromlist(v) | |
def __mul__(self, scalar): | |
# Multiply by scalar | |
v = [x * scalar for x in self.v] | |
return Vec.fromlist(v) | |
__rmul__ = __mul__ | |
def test(): | |
import doctest | |
doctest.testmod() | |
test() |