Keep items with same keys in two dictionary and discard other items

I am trying to remove all non-matching items (values with different keys) in two dicts dict_a and dict_b. What is a better way of achieving this?

Example:

dict_a = {key1: x1, key2: y1, key4: z1}
dict_b = {key1: x2, key3: y2, key4: w1}
# becomes:
# dict_a = {key1: x1, key4: z1}
# dict_b = {key1: x2, key4: w1}

My attempt:

keep_keys = [keyA for keyA in dict_a.keys() if keyA in dict_b.keys()]

for i in dict_b.copy().keys():
    if i not in keep_keys:
        del dict_b[i]

for i in dict_a.copy().keys():
    if i not in keep_keys:
        del dict_a[i]

I am looking for shorter (pythonic) way of doing this.

It's not a lot better, but this uses a so-called "dictionary comprehension" to achieve it. It's effectively a for loop in one line (but two lines here since we have two dictionaries).

dict_a = {k: v for k, v in dict_a.items() if k in dict_b}
dict_b = {k: v for k, v in dict_b.items() if k in dict_a}

This below also works, and is technically shorter but (maybe?) less Pythonic

dict_a = {k: dict_a[k] for k in dict_a if k in dict_b}
dict_b = {k: dict_b[k] for k in dict_b if k in dict_a}

If you flip the problem into removing non-shared keys, it becomes a bit easier: get non-shared keys using XOR (setlike), then delete them where they occur.

d1 = {'key1': 'x1', 'key2': 'y1', 'key4': 'z1'}
d2 = {'key1': 'x2', 'key3': 'y2', 'key4': 'w1'}

discard_keys = d1.keys() ^ d2.keys()
for k in discard_keys:
    if k in d1:
        del d1[k]
    if k in d2:
        del d2[k]

print(d1)
print(d2)

{'key1': 'x1', 'key4': 'z1'}
{'key1': 'x2', 'key4': 'w1'}

You can do:

d1 = {"key1": "x1", "key2": "y1", "key4": "z1"}
d2 = {"key1": "x2", "key3": "y2", "key4": "w1"}

common_keys = d1.keys() & d2.keys()

d1 = {k: d1[k] for k in common_keys}
d2 = {k: d2[k] for k in common_keys}

print(d1)
print(d2)

Prints:

{'key1': 'x1', 'key4': 'z1'}
{'key1': 'x2', 'key4': 'w1'}