Compare two nested dictionaries

[Steven D'Aprano]

On Sun, 25 Jul 2010 08:03:06 -0700, targetsmart wrote:

> Hi,
> I am trying to compare two nested dictionaries, I want to know what is
> the exact difference between them. I tried this solution
> 
> ...
>         s1 = set(result1)
>         s2 = set(result2)
>         print s1 - s2
> 
> but it doesn't seem show any difference, but
> 
> assert result1 == result2
> fails
> 
> could someone help me to find out the difference the two nested
> dictionaries.

Have you tried printing them and just looking for the differences?

Calling set() on a dictionary will create a set from the keys only:

>>> d1 = {"a": 1, "b": 2}
>>> d2 = {"a": 1, "b": 999}
>>> set(d1) == set(d2)
True
>>> d1 == d2
False

If you want to know the difference between two dictionaries, you have to 
consider:

(1) Keys that are in the first dict, but not the second;

(2) Keys that are in the second dict, but not the first; and

(3) Keys which are in both dicts, but have different values.


-- 
Steven