Demo/classes/Vec.py

   1 # A simple vector class
   2
   3
   4 def vec(*v):
   5         return apply(Vec, v)
   6
   7
   8 class Vec:
   9
  10         def __init__(self, *v):
  11                 self.v = []
  12                 for x in v:
  13                         self.v.append(x)
  14
  15
  16         def fromlist(self, v):
  17                 self.v = []
  18                 if type(v) <> type([]):
  19                         raise TypeError
  20                 self.v = v[:]
  21                 return self
  22
  23
  24         def __repr__(self):
  25                 return 'vec(' + `self.v`[1:-1] + ')'
  26
  27         def __len__(self):
  28                 return len(self.v)
  29
  30         def __getitem__(self, i):
  31                 return self.v[i]
  32
  33         def __add__(a, b):
  34                 # Element-wise addition
  35                 v = []
  36                 for i in range(len(a)):
  37                         v.append(a[i] + b[i])
  38                 return Vec().fromlist(v)
  39
  40         def __sub__(a, b):
  41                 # Element-wise subtraction
  42                 v = []
  43                 for i in range(len(a)):
  44                         v.append(a[i] - b[i])
  45                 return Vec().fromlist(v)
  46
  47         def __mul__(self, scalar):
  48                 # Multiply by scalar
  49                 v = []
  50                 for i in range(len(self.v)):
  51                         v.append(self.v[i]*scalar)
  52                 return Vec().fromlist(v)
  53
  54
  55
  56 def test():
  57         a = vec(1, 2, 3)
  58         b = vec(3, 2, 1)
  59         print a
  60         print b
  61         print a+b
  62         print a*3.0
  63
  64 test()