Python 3.6+: Equality Of Two Dictionaries With Same Keys But In Different Order

For two dictionaries d1 and d2 defined as d1 = {'foo':123, 'bar':789} d2 = {'bar':789, 'foo':123} The order of the keys is preserved in Python 3.6+. This is evident when we loop

Solution 1:

Dictionaries are hash tables, order is not supposed to matter. In python 3.6+ dictionaries are in insertion order but that is just how they are implemented. Order doesn't matter for equality. If you want order to matter in equality use an OrderedDict.

from collections import OrderedDict

d1 = OrderedDict({'foo':123, 'bar':789})
d2 = OrderedDict({'bar':789, 'foo':123})

print(d1 == d2) # False

Solution 2:

Dictionaries were unordered up until Python 3.6. Therefore the only sensible way to test for equality was to ignore the order. When Python 3.6 ordered dictionaries this was an implementation detail. Since Python 3.7 the insertion order can be relied upon. But changing the behavior to only consider dictionaries only equal if the keys are in the same order would break a whole lot of code. And quite frankly I think it is more useful to compare dictionaries without taking the ordering into account.