convert a string to list of list

Question

I get this string for example:

s = '[1,0],[3,5],[5,6]'

I want to convert it to list.

If I do:

s.split("[*,*]")

then it doesn't work

I want to get this:

[[1,0],[3,5],[5,6]]

@RVA92 this clearly won't work, it would also split the inner lists and keep the `[` and `]` characters. — matszwecja, Feb 28 '22 at 12:26

score 2 · Answer 1 · answered Feb 28 '22 at 12:35

You might use literal_eval from ast module (part of standard library) for this task as follows

import ast
s = '[1,0],[3,5],[5,6]'
lst = list(ast.literal_eval(s))
print(lst)

output

[[1, 0], [3, 5], [5, 6]]

Note that s is literal for python's tuple so I used list for conversion into desired structure.

score 2 · Answer 2 · answered Feb 28 '22 at 12:37

2

If the input format is really fixed :

out = [list(map(int, w.split(","))) for w in s[1:-1].split("],[")]

this may be faster but this may be less robust depending on input strict format than a real parsing solution like literal_eval

answered Feb 28 '22 at 12:37

jmbarbier

score 1 · Answer 3 · answered Feb 28 '22 at 12:34

>>> import ast
>>> ast.literal_eval('[1,0],[3,5],[5,6]')
([1, 0], [3, 5], [5, 6])

literal_eval is more secure than eval in that it contains some logic to only actually evaluate valid literals.

Converting the result to a list() left as an exercise. (Hint hint.)

3 Answers3