bayesType.py

from sympy import S
from wrapt import ObjectProxy

"""
A class for quickly doing math on percentages,
using bayes theorum.
"""

one = S(1)

class Probability(ObjectProxy):
    """
    A percentage object, you can use it to properly
    add or subtract percentage from one another.
    When used with a regular number, acts like
    a regular number.
    """
    def __init__(self,wrapped):
        super().__init__(S(wrapped))
    
    def __add__(self,other):
        if isinstance(other, Probability):
            return Probability(self+(one-self)*other)
        return super().__add__(other)
    def __sub__(self,other):
        if isinstance(other, Probability):
            return Probability(self-self*other)
        return super().__sub__(other)

p = Probability

print(p(0.9)+p(0.2)+p(0.5))
print(p(0.9)+p("1/3"))
print(p(0.9)-p("1/3"))
print(p("1/3")+p("1/3")+p("1/3")+p("1/3")+p("1/3"))