Converting a string representation of a list into an actual list object

Question

I have a string that looks identical to a list, let’s say:

fruits = "['apple', 'orange', 'banana']"

What would be the way to convert that to a list object?

Asked By: Markum

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Source

Answer 1

I think this is what ast.literal_eval is for.

( http://docs.python.org/library/ast.html#ast.literal_eval )

Answered By: mgilson

Answer 2

>>> fruits = "['apple', 'orange', 'banana']"
>>> import ast
>>> fruits = ast.literal_eval(fruits)
>>> fruits
['apple', 'orange', 'banana']
>>> fruits[1]
'orange'

As pointed out in the comments ast.literal_eval is safe. From the docs:

Safely evaluate an expression node or a string containing a Python
expression. The string or node provided may only consist of the
following Python literal structures: strings, numbers, tuples, lists,
dicts, booleans, and None.

This can be used for safely evaluating strings containing Python
expressions from untrusted sources without the need to parse the
values oneself.

Answered By: fraxel

Answer 3

A simple call to eval() will do:

fruits = eval("['apple', 'orange', 'banana']")
fruits
> ['apple', 'orange', 'banana']

Or as explained in this article, the same can be accomplished a bit more safely (meaning: without risking unintended side-effects or malicious code injections) like this:

fruits = eval("['apple', 'orange', 'banana']", {'__builtins__':None}, {})

This solution has the advantage of not depending on additional modules.

Answered By: Óscar López

Converting a string representation of a list into an actual list object

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