type/rate.py

   1 #!/usr/bin/env python3
   2
   3 # © Copyright 2021-2022, Scott Gasch
   4
   5 """A class to represent a rate of change."""
   6
   7 from typing import Optional
   8
   9
  10 class Rate(object):
  11     """A class to represent a rate of change."""
  12
  13     def __init__(
  14         self,
  15         multiplier: Optional[float] = None,
  16         *,
  17         percentage: Optional[float] = None,
  18         percent_change: Optional[float] = None,
  19     ):
  20         count = 0
  21         if multiplier is not None:
  22             if isinstance(multiplier, str):
  23                 multiplier = multiplier.replace('%', '')
  24                 m = float(multiplier)
  25                 m /= 100
  26                 self.multiplier: float = m
  27             else:
  28                 self.multiplier = multiplier
  29             count += 1
  30         if percentage is not None:
  31             self.multiplier = percentage / 100
  32             count += 1
  33         if percent_change is not None:
  34             self.multiplier = 1.0 + percent_change / 100
  35             count += 1
  36         if count != 1:
  37             raise Exception('Exactly one of percentage, percent_change or multiplier is required.')
  38
  39     def apply_to(self, other):
  40         return self.__mul__(other)
  41
  42     def of(self, other):
  43         return self.__mul__(other)
  44
  45     def __float__(self):
  46         return self.multiplier
  47
  48     def __mul__(self, other):
  49         return self.multiplier * float(other)
  50
  51     __rmul__ = __mul__
  52
  53     def __truediv__(self, other):
  54         return self.multiplier / float(other)
  55
  56     def __add__(self, other):
  57         return self.multiplier + float(other)
  58
  59     __radd__ = __add__
  60
  61     def __sub__(self, other):
  62         return self.multiplier - float(other)
  63
  64     def __eq__(self, other):
  65         return self.multiplier == float(other)
  66
  67     def __ne__(self, other):
  68         return not self.__eq__(other)
  69
  70     def __lt__(self, other):
  71         return self.multiplier < float(other)
  72
  73     def __gt__(self, other):
  74         return self.multiplier > float(other)
  75
  76     def __le__(self, other):
  77         return self < other or self == other
  78
  79     def __ge__(self, other):
  80         return self > other or self == other
  81
  82     def __hash__(self):
  83         return self.multiplier
  84
  85     def __repr__(self, *, relative=False, places=3):
  86         if relative:
  87             percentage = (self.multiplier - 1.0) * 100.0
  88         else:
  89             percentage = self.multiplier * 100.0
  90         return f'{percentage:+.{places}f}%'