Преобразовать строковое представление списка в список

Вдохновленный некоторыми ответами выше, которые работают с базовыми пакетами Python, я сравнил производительность нескольких (используя Python 3.7.3):

Метод 1: ast

import ast
list(map(str.strip, ast.literal_eval(u'[ "A","B","C" , " D"]')))
# ['A', 'B', 'C', 'D']

import timeit
timeit.timeit(stmt="list(map(str.strip, ast.literal_eval(u'[ \"A\",\"B\",\"C\" , \" D\"]')))", setup='import ast', number=100000)
# 1.292875313000195

Метод 2: JSON

import json
list(map(str.strip, json.loads(u'[ "A","B","C" , " D"]')))
# ['A', 'B', 'C', 'D']

import timeit
timeit.timeit(stmt="list(map(str.strip, json.loads(u'[ \"A\",\"B\",\"C\" , \" D\"]')))", setup='import json', number=100000)
# 0.27833264000014424

Метод 3: нет импорта

list(map(str.strip, u'[ "A","B","C" , " D"]'.strip('][').replace('"', '').split(',')))
# ['A', 'B', 'C', 'D']

import timeit
timeit.timeit(stmt="list(map(str.strip, u'[ \"A\",\"B\",\"C\" , \" D\"]'.strip('][').replace('\"', '').split(',')))", number=100000)
# 0.12935059100027502

Я был разочарован, увидев то, что я считал методом с худшей читабельностью, это метод с наилучшей производительностью ... при выборе наиболее читаемой опции нужно учитывать компромиссы ... для типов рабочих нагрузок, которые я использую для python, я обычно оцениваю читаемость немного выше более производительный вариант, но, как обычно, зависит.

Не импортируя ничего:

>>> x = u'[ "A","B","C" , " D"]'
>>> ls = x.strip('[]').replace('"', '').replace(' ', '').split(',')
>>> ls
['A', 'B', 'C', 'D']

If you know that your lists only contain quoted strings, this pyparsing example will give you your list of stripped strings (even preserving the original Unicode-ness).

>>> from pyparsing import *
>>> x =u'[ "A","B","C" , " D"]'
>>> LBR,RBR = map(Suppress,"[]")
>>> qs = quotedString.setParseAction(removeQuotes, lambda t: t[0].strip())
>>> qsList = LBR + delimitedList(qs) + RBR
>>> print qsList.parseString(x).asList()
[u'A', u'B', u'C', u'D']

If your lists can have more datatypes, or even contain lists within lists, then you will need a more complete grammar - like this one on the pyparsing wiki, which will handle tuples, lists, ints, floats, and quoted strings. Will work with Python versions back to 2.4.

Assuming that all your inputs are lists and that the double quotes in the input actually don't matter, this can be done with a simple regexp replace. It is a bit perl-y but works like a charm. Note also that the output is now a list of unicode strings, you didn't specify that you needed that, but it seems to make sense given unicode input.

import re
x = u'[ "A","B","C" , " D"]'
junkers = re.compile('[[" \]]')
result = junkers.sub('', x).split(',')
print result
--->  [u'A', u'B', u'C', u'D']

The junkers variable contains a compiled regexp (for speed) of all characters we don't want, using ] as a character required some backslash trickery. The re.sub replaces all these characters with nothing, and we split the resulting string at the commas.

Note that this also removes spaces from inside entries u'["oh no"]' ---> [u'ohno']. If this is not what you wanted, the regexp needs to be souped up a bit.

import ast
l = ast.literal_eval('[ "A","B","C" , " D"]')
l = [i.strip() for i in l]

There is a quick solution:

x = eval('[ "A","B","C" , " D"]')

Unwanted whitespaces in the list elements may be removed in this way:

x = [x.strip() for x in eval('[ "A","B","C" , " D"]')]

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.