1 # A simple vector class

     2 

     3 

     4 def vec(*v):

     5     return Vec(*v)

     6 

     7 

     8 class Vec:

     9 

    10     def __init__(self, *v):

    11         self.v = list(v)

    12 

    13     def fromlist(self, v):

    14         if not isinstance(v, list):

    15             raise TypeError

    16         self.v = v[:]

    17         return self

    18 

    19     def __repr__(self):

    20         return 'vec(' + repr(self.v)[1:-1] + ')'

    21 

    22     def __len__(self):

    23         return len(self.v)

    24 

    25     def __getitem__(self, i):

    26         return self.v[i]

    27 

    28     def __add__(self, other):

    29         # Element-wise addition

    30         v = map(lambda x, y: x+y, self, other)

    31         return Vec().fromlist(v)

    32 

    33     def __sub__(self, other):

    34         # Element-wise subtraction

    35         v = map(lambda x, y: x-y, self, other)

    36         return Vec().fromlist(v)

    37 

    38     def __mul__(self, scalar):

    39         # Multiply by scalar

    40         v = map(lambda x: x*scalar, self.v)

    41         return Vec().fromlist(v)

    42 

    43 

    44 

    45 def test():

    46     a = vec(1, 2, 3)

    47     b = vec(3, 2, 1)

    48     print a

    49     print b

    50     print a+b

    51     print a-b

    52     print a*3.0

    53 

    54 test()