Question

dictionary is usually good for find value by key,but find key by value is pretty slow

for k,v in dictionary.items():
    if v = myValue:
        return k

is there already a data structure that make both key->value and ke

Answer 1

You could try bidict:

>>> husbands2wives = bidict({'john': 'jackie'})
>>> husbands2wives['john'] # the forward mapping is just like with dict
'jackie'
>>> husbands2wives[:'jackie'] # use slice for the inverse mapping
'john'