How do you check the presence of many keys in a Python dictionary?

Question

I have the following dictionary:

sites = {
    'stackoverflow': 1,
    'superuser': 2,
    'meta': 3,
    'serverfault': 4,
    'mathoverflow': 5
}

To check if there are more than one key available in the above dictionary, I will do something like:

'stackoverflow' in sites and 'serverfault' in sites

The above is maintainable with only 2 key lookups. Is there a better way to handle checking a large number of keys in a very big dictionary?

Answer 1

You can pretend the keys of the dict are a set, and then use set.issubset:

set(['stackoverflow', 'serverfault']).issubset(sites) # ==> True

set(['stackoverflow', 'google']).issubset(sites) # ==> False