Best way to check if value in dictionary of lists?

Question

So I have a dictionary of lists like so:

dct = {'1': ['hello','goodbye'], '2': ['not here','definitely not here']}

What's the fastest way to check if 'hello' is in one of my lists in my dictionary

Answer 1

As Willem Van Onsem commented, the easiest way to achieve this is:

any('hello' in val for val in dct.values())

any returns True if any of the values in the given iterable are truthy.

dct.values() returns a dict_values iterable that yields all the values in a dictionary.

'hello' in val for val in dct.values() is a generator expression that yields True for each value of dct that 'hello' is in.

If you want to know the keys the string is in, you can do:

keys = [key for key, value in dct.items() if 'hello' in value]

In your case, keys will be ['1']. If you do this anyways, you can then just call use that list in a boolean context, e.g. if keys: ....