How to access the last list in a list

Question

So let's say I have the following list.

[1,2,[3,4,5,6,[7,8,[9]]]]

Is there an easy way to access the list [9] without doing a function?

For that value, `x[-1][-1][-1]`, but I imagine you mean in the general case of nested lists... — AKX, Nov 21 '21 at 20:06
1) Flatten the list; 2) `flatten(list)[-1]` for the last element — dawg, Nov 21 '21 at 20:14
note that brtt requested the last list, not the last element. — Ori, Nov 21 '21 at 20:15

score 1 · Answer 1 · answered Nov 21 '21 at 21:06

1

You could use a while loop:

L  = [1,2,[3,4,5,6,[7,8,[9]]]]

lastList = L
while isinstance(lastList[-1],list): 
    lastList = lastList[-1]

print(lastList)
[9]

answered Nov 21 '21 at 21:06

Alain T.

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score 0 · Answer 2 · answered Nov 21 '21 at 20:09

0

Lambdas are functions with another syntax, so this answer might not be what you really want, but

>>> x = [1,2,[3,4,5,6,[7,8,[9]]]]
>>> z = lambda x: z(x[-1]) if len(x) > 1 else x
>>> z(x)
[9]

answered Nov 21 '21 at 20:09

AKX

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1

This is not a general solution. It only works in this narrow case. – dawg Nov 21 '21 at 20:15
1

@dawg But I guess it's the flaw of the question. The question was not clear enough how general the solution is expected. To me it is fairly general (in terms of the depth of nests), given the question. It is the question what is to be blamed. – j1-lee Nov 21 '21 at 20:23
Agreed. That is why I originally closed it but then saw that there was a pony in there... – dawg Nov 21 '21 at 20:29

score 0 · Answer 3 · answered Nov 21 '21 at 20:27

Suppose you have:

li=[1,2,[3,4,5,6,[7,8,[9,10]]]]

You can use a recursive function to find the last list:

def flatten(L):
  last_list=[]
  for item in L:
    try:
      last_list.append(item)
      yield from flatten(item)
    except TypeError:
      yield last_list

Then just exhaust the generator and the last one is the last list:

>>> for l in flatten(li): pass
>>> l
[9,10]
>>>

How to access the last list in a list

3 Answers3