I need to convert the given list of String format to a single list

Question

need to convert this list :

a = ["['0221', '02194', '02211']"]

type = list

to this list :

a = ['0221', '02194', '02211']

type = list

the list you have is list of string not list of list, you can simply do `a[0]` to get the first element — Abhishek, Oct 05 '21 at 06:20
To turn the first element from a string into a list you can use [astliteral_eval](https://stackoverflow.com/questions/29552950/when-to-use-ast-literal-eval): `a = ast.literal_eval(a[0])` — DarrylG, Oct 05 '21 at 06:22
@DarrylG , Why unnecessarily complicating, just use `a=a[0]`. — Faraaz Kurawle, Oct 05 '21 at 06:52
@FaraazKurawle--because a[0] is the string `"['0221', '02194', '02211']"`. OP wants to convert the string into a list. — DarrylG, Oct 05 '21 at 06:54

Faraaz Kurawle · Answer 1 · 2021-10-05T07:51:21.733

If your new to python this code would seem like very complicated, but i will explain whats in this piece of code:

a=["['0221', '02194', '02211']"]
a1=[]
nums_str=""
for i in a:
    for j in i:
        try:
            if j=="," or j=="]":
                a1.append(nums_str)
                nums_str=""
            nums=int(j)
            nums_str+=str(nums)
        except Exception as e:
            pass
else:
    a=a1.copy()
print(a)
print(type(a))

Steps:

Used for loop to read the content in list a.
Then again used a for loop to read each character in the string of i.
Then used try to try if i can typecast j into int so that it would only add the numbers to nums_str.
Then appended the nums_str to the list a1 if j if = "," or "]".
Continued the above process on each item in a.
After the for loop gets over, i change a to copy of a1.

Papis Sahine · Answer 2 · 2021-10-05T07:29:24.257

0

You can try list comprehension:

 a = a[0][2:][:-2].split("', '")

output:

a = ['0221', '02194', '02211']

edited Oct 05 '21 at 07:29

answered Oct 05 '21 at 06:24

Papis Sahine

105
8

Have you actually tried that? – user2390182 Oct 05 '21 at 06:27
Not my downvote, but I get a different output. – DarrylG Oct 05 '21 at 06:27
yes of courses it works – Papis Sahine Oct 05 '21 at 06:28
oh I see let me edit my answer – Papis Sahine Oct 05 '21 at 06:29

score 0 · Answer 3 · answered Oct 05 '21 at 06:31

You can use astliteral_eval to convert strings to Python data structures. In this case, we want to convert the first element in the list a to a list.

import ast
a = ast.literal_eval(a[0])

print(a)
# ['0221', '02194', '02211']

Note: Python built-in function eval also works but it's considered unsafe on arbitray strings. With eval:

a = eval(a[0])  # same desired output

I need to convert the given list of String format to a single list

3 Answers3