Intersecting two dictionaries in Python

Question

I am working on a search program over an inverted index. The index itself is a dictionary whose keys are terms and whose values are themselves dictionaries of short document

Answer 1

In Python, you use the & operator to calculate the intersection of sets, and dictionary keys are set-like objects (in Python 3):

dict_a = {"a": 1, "b": 2}
dict_b = {"a": 2, "c": 3} 

intersection = dict_a.keys() & dict_b.keys()  # {'a'}

On Python 2 you have to convert the dictionary keys to sets yourself:

keys_a = set(dict_a.keys())
keys_b = set(dict_b.keys())
intersection = keys_a & keys_b