Filter a dict of dict

Question

I new in Python and I am not sure it is a good idea to use dict of dict but here is my question. I have a dict of dict and I want to filter by the key of the inside dict:

Answer 1

You can do with a dictionary comprehension:

def query(data, query):
    return {key : {query : data[key][query]} 
            for key in data if query in data[key]}

You have to look at each entry of the dictionary, which can cost a lot of time if you have many entries or do this a lot. A database with a index can speed this up.