operators.py

   1 from math import sqrt
   2
   3 import number
   4 from exc import IncompatibleUnits
   5
   6
   7
   8 OPERATORS_ALL=[]
   9
  10 OP_CLASSES=[]
  11 OPERATORS_ARITHMETIC=[]
  12
  13 def register_operator(cl):
  14     OP_CLASSES.append(cl)
  15     return cl
  16
  17 class GenericOp(object):
  18     def __init__(self, arity, commutativity, name):
  19         self.arity = arity
  20         self.commutativity = commutativity
  21         self.name = name
  22
  23     def __call__(self, args):
  24         assert len(args) == self.getArity()
  25         values = map(lambda n: n.getValue(), args)
  26         sdsqs = map(lambda n: n.getSdSquare(), args)
  27         units = map(lambda n: n.getUnits(), args)
  28
  29         new_value, new_sdsq, new_units = self.computeNewNumber(values, sdsqs, units)
  30         return number.Number(new_value, sdsq=new_sdsq, string=self.name, units=new_units, parents=args)
  31
  32     def computeNewNumber(self, values, sdsqs, units):
  33         raise NotImplementedError
  34
  35     def getArity(self):
  36         return self.arity
  37
  38     def isCommutative(self):
  39         return self.commutativity
  40 #
  41 #
  42 #   Arithmetic Operators
  43 #
  44
  45 @register_operator
  46 class Plus(GenericOp):
  47     def __init__(self):
  48         super(Plus, self).__init__(2, True, "Plus")
  49
  50     def computeNewNumber(self, (n1v, n2v), (n1sdsq, n2sdsq), (u1, u2)):
  51         if u1 != u2:
  52             raise IncompatibleUnits
  53         new_value = n1v + n2v
  54         new_sdsq = n1sdsq + n2sdsq
  55         return new_value, new_sdsq, u1
  56
  57 @register_operator
  58 class Minus(GenericOp):
  59     def __init__(self):
  60         super(Minus, self).__init__(2, False, "Minus")
  61
  62     def computeNewNumber(self, (n1v, n2v), (n1sdsq, n2sdsq), (u1, u2)):
  63         if u1 != u2:
  64             raise IncompatibleUnits
  65         new_value = n1v - n2v
  66         new_sdsq = n1sdsq + n2sdsq
  67         return new_value, new_sdsq, u1
  68
  69 @register_operator
  70 class Mult(GenericOp):
  71     def __init__(self):
  72         super(Mult, self).__init__(2, True, "Mult")
  73
  74     def computeNewNumber(self, (n1v, n2v), (n1sdsq, n2sdsq), (u1, u2)):
  75         new_value = n1v * n2v
  76         new_sdsq = n1v**2 * n2sdsq + n2v**2 * n1sdsq
  77         return new_value, new_sdsq, number.units_join(u1, u2)
  78
  79 @register_operator
  80 class Div(GenericOp):
  81     def __init__(self):
  82         super(Div, self).__init__(2, False, "Div")
  83
  84     def computeNewNumber(self, (n1v, n2v), (n1sdsq, n2sdsq), (u1, u2)):
  85         new_value = n1v / n2v
  86         new_sdsq = n2v**(-2) * n1sdsq + n1v**2 * n2v**(-4) * n2sdsq
  87         return new_value, new_sdsq, number.units_diff(u1, u2)
  88
  89 #
  90 #       Numeric operators
  91 #
  92 # e.g. op(number) -> 2 * number
  93 #
  94
  95 class Times(GenericOp):
  96     def __init__(self, num):
  97         super(Times, self).__init__(1, True, str(num))
  98         self.num=num
  99
 100     def computeNewNumber(self, (n1v,), (n1sdsq, ), (u1,)):
 101         new_value = self.num * n1v
 102         new_sdsq = self.num**2 * n1sdsq
 103         return new_value, new_sdsq, u1
 104
 105 #
 106 #       Unit Conversions
 107 #
 108
 109 # TODO TODO TODO
 110
 111 #
 112 #   All together
 113 #
 114
 115 OPERATORS_ARITHMETIC = map(lambda x: x() , OP_CLASSES)
 116