Assuming there is no problem with opening the file, here are some hints.

Your list `L`

contains the lines of the file `f`

, which seems to be only one line. Hence `L[0]`

is a string that looks like `"0,1,0,1,1,....,1\n"`

with `\n`

standing for the line feed character.

To extract the elements of that list, remove that character, then split the string to get a list:

```
sage: L[0].replace('\n','').split(',')
['0', '1', '0', '1', '1',..., '1']
```

Then turn that list of strings into a list of integers:

```
sage: A = [ZZ(i) for i in L[0].replace('\n','').split(',')]
sage: A
[0, 1, 0, 1, 1, ..., 1]
```

Another (simpler) way is to use the `csv`

module that deals well with comma separated values:

```
sage: r = csv.reader(f)
sage: A = [ZZ(i) for i in next(r)]
sage: A
[0, 1, 0, 1, 1, ..., 1]
```

Finally, the Python documentation about reading and writing files
recommends using `with`

to deal with files.

So instead of

```
sage: f = open('path/abc.txt')
sage: L = f.readlines()
sage: A = [ZZ(i) for i in L[0].replace('\n','').split(',')]
```

the advice is to use

```
sage: with open('path/abc.txt', 'r') as f:
....: L = f.readlines()
sage: A = [ZZ(i) for i in L[0].replace('\n','').split(',')]
```

This takes care of closing the file after it has been used,
including if some error happens while reading from the file.

What error do you get ?