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)?

Answer 1

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

The shortest solution I can imagine.

Answer 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

Answer 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))

Answer 4

This is what I had come up with, but I like the other's better.

def deep_list(x):
      """fully copies trees of tuples or lists to a tree of lists.
         deep_list( (1,2,(3,4)) ) returns [1,2,[3,4]]
         deep_list( (1,2,[3,(4,5)]) ) returns [1,2,[3,[4,5]]]"""
      if not ( type(x) == type( () ) or type(x) == type( [] ) ):
          return x
      return map(deep_list,x)

I see aztek 's answer can be shortened to:

def deep_list(x):
     return map(deep_list, x) if isinstance(x, (list, tuple)) else x

Update : But now I see from DasIch 's comment that this wouldn't work in Python 3.x since map() there returns a generator.