python - How do I make a dictionary with multiple keys to one value?

Question

I have a question about a dictionary I want to make. My goal is to have multiple keys to a single value, like below:

dictionary = {('a', 'b'): 1, ('c', 'd'): 2}
assert dictionary['a'] == 1
assert dictionary['b'] == 1

Any ideas?

Answer 1

I guess you mean this:

class Value:
    def __init__(self, v=None):
        self.v = v

v1 = Value(1)
v2 = Value(2)

d = {'a': v1, 'b': v1, 'c': v2, 'd': v2}
d['a'].v += 1

d['b'].v == 2 # True

• Python's strings and numbers are immutable objects,
• So, if you want d['a'] and d['b'] to point to the same value that "updates" as it changes, make the value refer to a mutable object (user-defined class like above, or a dict, list, set).
• Then, when you modify the object at d['a'], d['b'] changes at same time because they both point to same object.