number.py

   1 # For licensing info see the included LICENSE file
   2 #
   3 # Josef Moudrik, <J dot Moudrik at standard google mail ending>, 2012
   4
   5 # -*- coding: utf-8 -*-
   6
   7 import math
   8
   9 from exc import IncompatibleUnits
  10 import operators
  11
  12 def units_op(u1, u2, op):
  13     u = {}
  14     for k in u1.viewkeys() | u2.viewkeys():
  15         v1, v2 = u1.get(k, 0), u2.get(k, 0)
  16         v = op( v1, v2 )
  17         if v != 0:
  18             u[k] = v
  19     return u
  20
  21 def units_diff(u1, u2):
  22     return units_op(u1, u2, lambda x, y : x - y)
  23
  24 def units_join(u1, u2):
  25     return units_op(u1, u2, lambda x, y : x + y)
  26
  27 class Number:
  28     def __init__(self, value, sdsq=0, units=None, string='', parents=None):
  29         if units == None:
  30             units = {}
  31
  32         self.value = float(value)
  33         self.sdsq = sdsq
  34         self.units = units
  35         self.string = string
  36         self.parents = parents
  37
  38     def __add__(self, other):
  39         return operators.Plus()((self, other))
  40
  41     def __sub__(self, other):
  42         return operators.Minus()((self, other))
  43
  44     def __mul__(self, other):
  45         return operators.Mult()((self, other))
  46
  47     def __rmul__(self, other):
  48         assert isinstance(other, int) or isinstance(other, float)
  49
  50         return operators.Times(other)((self,))
  51
  52     def __div__(self, other):
  53         return operators.Div()((self, other))
  54
  55     def getDifference(self, other):
  56     # TODO lip??
  57         if self.getUnits() != other.getUnits():
  58             raise IncompatibleUnits
  59
  60         assert self.sdsq == 0
  61
  62         diff = abs(1.0 - other.getValue() / self.getValue())
  63
  64         op = other.getSdPerc()
  65         if diff < op:
  66             return op
  67
  68         return diff
  69
  70     def getValue(self):
  71         return self.value
  72
  73     def getSdSquare(self):
  74         return self.sdsq
  75
  76     def getSd(self):
  77         return math.sqrt(self.getSdSquare())
  78
  79     def getSdPerc(self):
  80         return self.getSd() / abs(self.getValue())
  81
  82     def getUnits(self):
  83         return self.units
  84
  85     def strUnits(self):
  86         l=[]
  87         for key in sorted(self.units.keys()):
  88             l.append(key)
  89             v = self.units[key]
  90             if v != 1:
  91                 l.append( '^%d'%(v,))
  92         return ''.join(l)
  93
  94     def longStr(self):
  95         return self.headStr() + " = " + str(self)
  96
  97     def headStr(self):
  98         return u'%.4f ± %.4f %s'%(self.getValue(), self.getSd(), self.strUnits())
  99
 100     def __str__(self):
 101         s = self.string
 102         if self.parents:
 103             s += "(%s)"%(', '.join(map(str, self.parents), ), )
 104         return s