Python - List of lists of different lengths

Question

I need to create a list which contains two lists. Something like

biglist = [list1,list2]

with

list1 = [1,2,3]
list2 = [4,5,6,7,8]

where list1 and list2 have DIFFERENT length and are imported from file.

I did it the following way:

biglist = []
list1 = #...taken from file. I checked this and it poduces a list exactly how I want it to be: [1,2,3]
biglist.append(list1)

and likewise for list2

but the problem is that I get

biglist = [array([1,2,3]),array([4,5,6,7,8])]

as opposed to

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

and I really don't want the array thing, I prefer to have simple lists. how to get around this?

Solution 1

please try:

biglist.append(list(list1))
biglist.append(list(list2))

or if they are numpy arrays

biglist.append(list1.tolist())
biglist.append(list2.tolist())

Solution 2

Just convert your list1 and list2 (those are confusing names indeed because those are numpy arrays, just a comment) with numpy.ndarray.tolist() method and that's it

biglist = [list1.tolist(), list2.tolist()]

Comments

[enterML]

It seems that your list1 and list2 are numpy arrays. You can do this first: list1 = list.tolist() list2 = list2.tolist() and then append them to your big list

[user1767754]

use extend instead of append

[A.J. Uppal]

Please show the code where you parse the list from the file, because it is in that code that your list is parsed as a numpy array rather than a python list.

[user1767754]

tolist? what python version is that?

[skrubber]

there's no such method for lists

[A.J. Uppal]

It exists for numpy.array types

[skrubber]

@ᴬᴶᵁᴾᴾᴬᴸ I think the asker made it clear that the two objects are lists

[A.J. Uppal]

@Mokshyam no the OP didn't. Just because the variable name has "list" in it doesn't make it a list. If you look at the latter part of the post, the lists are shown as array([1,2,3]). This is a numpy.array, not a list.

[Simon Mengong]

list1 and list2 are imported, so when he does this, biglist has the array things that he does not want. That's the issue

[Saelyth]

Oh, I see now, that's tricky. The only fix that comes into my mind is.. I will update this answer.

[Damian Lattenero]

Thanks for the correction, it's a good answer and it's a plus one :)

[Damian Lattenero]

@user1767754 I modified the answer, I didn't clarify that the names wasn't the best, list1 is not a list is a npArray :), thanks for comment

[Damian Lattenero]

@Mokshyam You are absolutely right, that's why I added in the edit of my answer, that I was talking about npArrays, not python list, even if the name of variables are list1, they are array, not list

[Damian Lattenero]

@ᴬᴶᵁᴾᴾᴬᴸ thanks so much for helping me clarify my answer you rules :)