How do I convert a nested tuple of tuples and lists to lists of lists in Python?

Question

I have a tuple containing lists and more tuples. I need to convert it to nested lists with the same structure. For example, I want to convert (1,2,[3,(4,5)]) to [1,2,[3,[4,5]]].

How do I do this (in Python)?

Solution 1

def listit(t):
    return list(map(listit, t)) if isinstance(t, (list, tuple)) else t

The shortest solution I can imagine.

Solution 2

As a python newbie I would try this

def f(t):
    if type(t) == list or type(t) == tuple:
        return [f(i) for i in t]
    return t

t = (1,2,[3,(4,5)]) 
f(t)
>>> [1, 2, [3, [4, 5]]]

Or, if you like one liners:

def f(t):
    return [f(i) for i in t] if isinstance(t, (list, tuple)) else t

Solution 3

We can (ab)use the fact that json.loads always produces Python lists for JSON lists, while json.dumps turns any Python collection into a JSON list:

import json

def nested_list(nested_collection):
    return json.loads(json.dumps(nested_collection))