Comparing two dictionaries and checking how many (key, value) pairs are equal

If you want to know how many values match in both the dictionaries, you should have said that :)

Maybe something like this:

shared_items = {k: x[k] for k in x if k in y and x[k] == y[k]}
print len(shared_items)

What you want to do is simply x==y

What you do is not a good idea, because the items in a dictionary are not supposed to have any order. You might be comparing [('a',1),('b',1)] with [('b',1), ('a',1)] (same dictionaries, different order).

For example, see this:

>>> x = dict(a=2, b=2,c=3, d=4)
>>> x
{'a': 2, 'c': 3, 'b': 2, 'd': 4}
>>> y = dict(b=2,c=3, d=4)
>>> y
{'c': 3, 'b': 2, 'd': 4}
>>> zip(x.iteritems(), y.iteritems())
[(('a', 2), ('c', 3)), (('c', 3), ('b', 2)), (('b', 2), ('d', 4))]

The difference is only one item, but your algorithm will see that all items are different

def dict_compare(d1, d2):
    d1_keys = set(d1.keys())
    d2_keys = set(d2.keys())
    shared_keys = d1_keys.intersection(d2_keys)
    added = d1_keys - d2_keys
    removed = d2_keys - d1_keys
    modified = {o : (d1[o], d2[o]) for o in shared_keys if d1[o] != d2[o]}
    same = set(o for o in shared_keys if d1[o] == d2[o])
    return added, removed, modified, same

x = dict(a=1, b=2)
y = dict(a=2, b=2)
added, removed, modified, same = dict_compare(x, y)

dic1 == dic2

From python docs:

The following examples all return a dictionary equal to {"one": 1, "two": 2, "three": 3}:

>>> a = dict(one=1, two=2, three=3)
>>> b = {'one': 1, 'two': 2, 'three': 3}
>>> c = dict(zip(['one', 'two', 'three'], [1, 2, 3]))
>>> d = dict([('two', 2), ('one', 1), ('three', 3)])
>>> e = dict({'three': 3, 'one': 1, 'two': 2})
>>> a == b == c == d == e
True

Providing keyword arguments as in the first example only works for keys that are valid Python identifiers. Otherwise, any valid keys can be used.

Comparison is valid for both python2 and python3.