Convert string representation of list to list
I was wondering what the simplest way is to convert a string list like the following to a list :
x = u'[ "A","B","C" , " D"]'
Even in case user puts spaces in between the commas, and spaces inside of the quotes. I need to handle that as well to:
x = ["A", "B", "C", "D"]
in Python.
I know I can strip spaces with strip() and split() using the split operator and check for non alphabets. But the code was getting very kludgy. Is there a quick function that I'm not aware of?
>>> import ast
>>> x = u'[ "A","B","C" , " D"]'
>>> x = ast.literal_eval(x)
>>> x
['A', 'B', 'C', ' D']
>>> x = [n.strip() for n in x]
>>> x
['A', 'B', 'C', 'D']
ast.literal_eval:
With ast.literal_eval, you can 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.
The eval is dangerous - you shouldn't execute user input.
If you have 2.6 or newer, use ast instead of eval:
>>> import ast
>>> ast.literal_eval('["A","B" ,"C" ," D"]')
["A", "B", "C", " D"]
Once you have that, strip the strings.
If you're on an older version of Python, you can get very close to what you want with a simple regular expression:
>>> x='[ "A", " B", "C","D "]'
>>> re.findall(r'"s*([^"]*?)s*"', x)
['A', 'B', 'C', 'D']
This isn't as good as the ast solution, for example it doesn't correctly handle escaped quotes in strings. But it's simple, doesn't involve a dangerous eval, and might be good enough for your purpose if you're on an older Python without ast.
The json module is a better solution whenever there is a stringified list of dictionaries. The json.loads(your_data) function can be used to convert it to a list.
>>> import json
>>> x = u'[ "A","B","C" , " D"]'
>>> json.loads(x)
[u'A', u'B', u'C', u' D']
Similarly
>>> x = u'[ "A","B","C" , {"D":"E"}]'
>>> json.loads(x)
[u'A', u'B', u'C', {u'D': u'E'}]
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