conversion_utils.py

   1 #!/usr/bin/env python3
   2
   3 from numbers import Number
   4 from typing import Callable
   5
   6
   7 class Converter(object):
   8     def __init__(self,
   9                  name: str,
  10                  category: str,
  11                  to_canonical: Callable,
  12                  from_canonical: Callable,
  13                  unit: str) -> None:
  14         self.name = name
  15         self.category = category
  16         self.to_canonical = to_canonical
  17         self.from_canonical = from_canonical
  18         self.unit = unit
  19
  20     def to_canonical(self, n: Number) -> Number:
  21         return self.to_canonical(n)
  22
  23     def from_canonical(self, n: Number) -> Number:
  24         return self.from_canonical(n)
  25
  26     def unit_suffix(self) -> str:
  27         return self.unit
  28
  29
  30 conversion_catalog = {
  31     "Fahrenheit": Converter("Fahrenheit",
  32                             "temperature",
  33                             lambda f: (f - 32.0) * 0.55555555,
  34                             lambda c: c * 1.8 + 32.0,
  35                             "°F"),
  36     "Celsius": Converter("Celsius",
  37                          "temperature",
  38                          lambda c: c,
  39                          lambda c: c,
  40                          "°C"),
  41     "Kelvin": Converter("Kelvin",
  42                         "temperature",
  43                         lambda k: k - 273.15,
  44                         lambda c: c + 273.15,
  45                         "°K"),
  46 }
  47
  48
  49 def convert(magnitude: Number,
  50             from_thing: str,
  51             to_thing: str) -> Number:
  52     src = conversion_catalog.get(from_thing, None)
  53     dst = conversion_catalog.get(to_thing, None)
  54     if src is None or dst is None:
  55         raise ValueError("No known conversion")
  56     return _convert(magnitude, src, dst)
  57
  58
  59 def _convert(magnitude: Number,
  60              from_unit: Converter,
  61              to_unit: Converter) -> Number:
  62     canonical = from_unit.to_canonical(magnitude)
  63     converted = to_unit.from_canonical(canonical)
  64     return converted
  65
  66
  67 def f_to_c(temp_f: float) -> float:
  68     """Fahrenheit to Celsius."""
  69     return convert(temp_f, "Fahrenheit", "Celsius")
  70
  71
  72 def c_to_f(temp_c: float) -> float:
  73     """Celsius to Fahrenheit."""
  74     return convert(temp_c, "Celsius", "Fahrenheit")