Converting subset of strings to integers in a list

Question

I frequently find myself with a list that looks like this:

lst = ['A', '1', '2', 'B', '1', 'C', 'D', '4', '1', '4', '5', 'Z', 'D']

What is the most pythonic way to convert specific strings in this list to ints?

I typically do something like this:

lst = [lst[0], int(lst[1]), int(lst[2]), lst[3], ...]

The above approach seems wrong. Are there better way to convert only certain items in lists to integers?

Answer 1

I would say something like:

>>> lst = ['A', '1', '2', 'B', '1', 'C', 'D', '4', '1', '4', '5', 'Z', 'D']
>>> lst = [int(s) if s.isdigit() else s for s in lst]
>>> lst
['A', 1, 2, 'B', 1, 'C', 'D', 4, 1, 4, 5, 'Z', 'D']

Answer 2

int and .isdigit can disagree in Unicode case i.e., int might fail to parse a string even if .isdigit returns True for the string.

def maybe_int(s):
    try:
        return int(s)
    except ValueError:
        return s

lst = [maybe_int(s) for s in lst]