type/rate.py

   1 #!/usr/bin/env python3
   2
   3 """A class to represent a rate of change."""
   4
   5 from typing import Optional
   6
   7
   8 class Rate(object):
   9     """A class to represent a rate of change."""
  10
  11     def __init__(
  12         self,
  13         multiplier: Optional[float] = None,
  14         *,
  15         percentage: Optional[float] = None,
  16         percent_change: Optional[float] = None,
  17     ):
  18         count = 0
  19         if multiplier is not None:
  20             if isinstance(multiplier, str):
  21                 multiplier = multiplier.replace('%', '')
  22                 m = float(multiplier)
  23                 m /= 100
  24                 self.multiplier: float = m
  25             else:
  26                 self.multiplier = multiplier
  27             count += 1
  28         if percentage is not None:
  29             self.multiplier = percentage / 100
  30             count += 1
  31         if percent_change is not None:
  32             self.multiplier = 1.0 + percent_change / 100
  33             count += 1
  34         if count != 1:
  35             raise Exception('Exactly one of percentage, percent_change or multiplier is required.')
  36
  37     def apply_to(self, other):
  38         return self.__mul__(other)
  39
  40     def of(self, other):
  41         return self.__mul__(other)
  42
  43     def __float__(self):
  44         return self.multiplier
  45
  46     def __mul__(self, other):
  47         return self.multiplier * float(other)
  48
  49     __rmul__ = __mul__
  50
  51     def __truediv__(self, other):
  52         return self.multiplier / float(other)
  53
  54     def __add__(self, other):
  55         return self.multiplier + float(other)
  56
  57     __radd__ = __add__
  58
  59     def __sub__(self, other):
  60         return self.multiplier - float(other)
  61
  62     def __eq__(self, other):
  63         return self.multiplier == float(other)
  64
  65     def __ne__(self, other):
  66         return not self.__eq__(other)
  67
  68     def __lt__(self, other):
  69         return self.multiplier < float(other)
  70
  71     def __gt__(self, other):
  72         return self.multiplier > float(other)
  73
  74     def __le__(self, other):
  75         return self < other or self == other
  76
  77     def __ge__(self, other):
  78         return self > other or self == other
  79
  80     def __hash__(self):
  81         return self.multiplier
  82
  83     def __repr__(self, *, relative=False, places=3):
  84         if relative:
  85             percentage = (self.multiplier - 1.0) * 100.0
  86         else:
  87             percentage = self.multiplier * 100.0
  88         return f'{percentage:+.{places}f}%'