Python – How to convert string representation of list to a list

pythonstring

I was wondering what the simplest way is to convert a string representation of a list like the following to a list:

x = '[ "A","B","C" , " D"]'

Even in cases where the user puts spaces in between the commas, and spaces inside of the quotes, I need to handle that as well and convert it to:

x = ["A", "B", "C", "D"]

I know I can strip spaces with strip() and split() and check for non-letter characters. But the code was getting very kludgy. Is there a quick function that I'm not aware of?

Best Solution

>>> import ast
>>> x = '[ "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 literal or container display. The string or node provided may only consist of the following Python literal structures: strings, bytes, numbers, tuples, lists, dicts, booleans, and None.

This is the style that Microsoft tends to use in their examples.

It appears that the guidance in this area may have changed, as StyleCop now enforces the use of the C# specific aliases.

C++ – How to iterate over the words of a string

I use this to split string by a delimiter. The first puts the results in a pre-constructed vector, the second returns a new vector.

#include <string>
#include <sstream>
#include <vector>
#include <iterator>

template <typename Out>
void split(const std::string &s, char delim, Out result) {
    std::istringstream iss(s);
    std::string item;
    while (std::getline(iss, item, delim)) {
        *result++ = item;
    }
}

std::vector<std::string> split(const std::string &s, char delim) {
    std::vector<std::string> elems;
    split(s, delim, std::back_inserter(elems));
    return elems;
}

Note that this solution does not skip empty tokens, so the following will find 4 items, one of which is empty:

std::vector<std::string> x = split("one:two::three", ':');

Best Solution

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This is the style that Microsoft tends to use in their examples.

C++ – How to iterate over the words of a string

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