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# A simple vector class
import operator
class Vec:
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):
return 'Vec(' + repr(self.v)[1:-1] + ')'
def __len__(self):
return len(self.v)
def __getitem__(self, i):
return self.v[i]
def __add__(self, other):
# Element-wise addition
v = list(map(operator.add, self, other))
return Vec.fromlist(v)
def __sub__(self, other):
# Element-wise subtraction
v = list(map(operator.sub, self, other))
return Vec.fromlist(v)
def __mul__(self, scalar):
# Multiply by scalar
v = [x*scalar for x in self.v]
return Vec.fromlist(v)
def test():
a = Vec(1, 2, 3)
b = Vec(3, 2, 1)
print(a)
print(b)
print(a+b)
print(a-b)
print(a*3.0)
test()
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