Accessing nested keys in Python

Question

I have a nested dictionary as below

entry = {
    0: {"Q": 0},
    1: {"W": 2, "E": 3, "N": 5, "S": 4, "Q": 0},
    2: {
        "N": {
            "Q": {"E"}
        }
    },
}

When I try to access only the keys for the key 1, I get the following:

>>> print(entry[1].keys())
dict_keys(['W', 'E', 'N', 'S', 'Q'])

But for key 2 it only returns the top key and not the nested key.

>>> print(entry[2].keys())
dict_keys(['N'])  

Why is it not returning the nested key of the dictionary?

Answer 1

keys()doesn't work that way.

keys()

Return a new view of the dictionary’s keys

Your nested dictionnary is a completely separate dict, and you can get its own keys with its own keys() method :

entry[2]['N'].keys()

If you want to recursively get all the keys inside nested dictionnaries, you will have to implement a method for that :

entry = {0: {"Q": 0},
         1: {"W": 2, "E": 3, "N": 5, "S": 4, "Q": 0},
         2: {"N": { "Q":{"E"}}},
}


def rec_keys(dictio):
    keys = []
    for (key,value) in dictio.items():
        if isinstance(value, dict):
            keys.extend(rec_keys(value))
        else:
            keys.append(key)
    return keys

print(rec_keys(entry))
# ['Q', 'Q', 'W', 'N', 'S', 'E', 'Q']