| 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() |