How to convert list of intable strings to int

I'd use a custom function:

def try_int(x):
    try:
        return int(x)
    except ValueError:
        return x

Example:

>>> [try_int(x) for x in  ['sam', '1', 'dad', '21']]
['sam', 1, 'dad', 21]

---

Edit: If you need to apply the above to a list of lists, why didn't you converted those strings to int while building the nested list?

Anyway, if you need to, it's just a matter of choice on how to iterate over such nested list and apply the method above.

One way for doing that, might be:

>>> list_of_lists = [['aa', '2'], ['bb', '3']]
>>> [[try_int(x) for x in lst] for lst in list_of_lists]
[['aa', 2], ['bb', 3]]

You can obviusly reassign that to list_of_lists:

>>> list_of_lists = [[try_int(x) for x in lst] for lst in list_of_lists]

I would create a generator to do it:

def intify(lst):
    for i in lst:
        try:
            i = int(i)
        except ValueError:
            pass
        yield i

lst = ['sam','1','dad','21']
intified_list = list(intify(lst))
# or if you want to modify an existing list
# lst[:] = intify(lst)

If you want this to work on a list of lists, just:

new_list_of_lists = map(list, map(intify, list_of_lists))

How about using map and lambda

>>> map(lambda x:int(x) if x.isdigit() else x,['sam','1','dad','21'])
['sam', 1, 'dad', 21]

or with List comprehension

>>> [int(x) if x.isdigit() else x for x in ['sam','1','dad','21']]
['sam', 1, 'dad', 21]
>>> 

As mentioned in the comment, as isdigit may not capture negative numbers, here is a refined condition to handle it notable a string is a number if its alphanumeric and not a alphabet :-)

>>> [int(x) if x.isalnum() and not x.isalpha() else x for x in ['sam','1','dad','21']]
['sam', 1, 'dad', 21]