How to convert a list into a list of lists in python

Question

Here is an example of a list that I would like to convert into a list of lists in python:

p=[1,2,3,4]

I wrote the following code to address the problem:

u=[]
v=[x for x in p]
u.append(v)

my result: [[1,2,3,4]]

Result I would like to have: **[[1],[2],[3],[4]]**

Any suggestions? thanks.

Nitzle · Accepted Answer · 2013-09-17 15:55:48Z

6

Just make a small tweak to your list comprehension, and wrap the x in brackets to put each element in a list.

>>> p = [1, 2, 3, 4]
>>> v = [[x] for x in p]
>>> v
[[1], [2], [3], [4]]

answered Sep 17, 2013 at 15:55

Nitzle

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1 Comment

Many thanks Nitzle, I have solved similar problem in the past, but just couldn't think straight today.

Paul Evans · Accepted Answer · 2013-09-17 15:56:32Z

2

You want something like this:

u = [[x] for x in p]

answered Sep 17, 2013 at 15:56

Paul Evans

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Abhijit · Accepted Answer · 2013-09-17 15:58:02Z

1

As other answer have depicted, List Comprehension is a straightforward way, but there are alternatives

>>> map(list,zip(p))
[[1], [2], [3], [4]]

or

>>> from itertools import izip
>>> map(list,izip(p))
[[1], [2], [3], [4]]

answered Sep 17, 2013 at 15:58

Abhijit

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