CODEWITHSUNDEEP
pythonpython-3.xlistdictionary
Fedor Peplin
Fedor Peplin

Reputation: 149

Transferring list to a difficult hierarchical dictionary

Everybody, hello,

I have a task to transfer list like random_list=['2018-01-01', 'google', 'cpc', 100] (which could be expanded manually) into dictionary like {'2018-01-01': {'google': {'cpc': 100}}}, which is also could be expanded more, if the list is expanded.

For example, if I would add any string or int in list - it should be included in dictionary and be like {'2018-01-01': {'google': {'cpc': {100: 'example'}}}}, or {'2018-01-01': {'google': {'cpc': {'example': 100}}}}.

I've travelled a lot on this stack overflow website, and there are questions like that, but nothing compared to "included dictionary". I'm a new user here, and maybe in future my skills of searching here will be upgraded, but I can't find anything similar. I can transform it into a simple dictionaries, but nothing compared to that.

Upvotes: 1

Views: 38

Answers (2)

Thierry Lathuille
Thierry Lathuille

Reputation: 24282

You could also build it using functools.reduce:

from functools import reduce

random_list=['2018-01-01', 'google', 'cpc', 100]

reduce(lambda v, k: {k:v}, reversed(random_list[:-1]), random_list[-1])
# {'2018-01-01': {'google': {'cpc': 100}}}

We start with the initial value random_list[-1] (100), which will be passed as value when we start iterating backward on the rest of the list. On the first iteration, the dict {'cpc': 100} gets built. On each following iteration, the already built dict gets passed as value to build the next level of the dict.

Upvotes: 1

Nick
Nick

Reputation: 147206

This can be done by recursion, using the first entry in the list as a key to a value which is a nested dictionary created from the rest of the list:

def make_dict(l):
    if len(l) < 2:
        return None
    elif len(l) == 2:
        return { l[0] : l[1] }
    else: 
        return { l[0] : make_dict(l[1:]) }

print(make_dict(['2018-01-01', 'google', 'cpc', 100]))
print(make_dict(['2018-01-01', 'google', 'cpc', 100, 'example']))

Output:

{'2018-01-01': {'google': {'cpc': 100}}}
{'2018-01-01': {'google': {'cpc': {100: 'example'}}}}

Upvotes: 3

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