Correct way to change a list of strings to list of ints

Question

dict = {0: ['2', '6'], 1: ['2'], 2: ['3']}

print("Original: ")
print(dict)

for key,vals in dict.items():
    vals = [int(s) for s in vals]

print("New: ")
print(dict)

Output:

Original: 
{0: ['2', '6'], 1: ['2'], 2: ['3']}
New: 
{0: ['2', '6'], 1: ['2'], 2: ['3']}

I can't figure why the list of values is not changing, I have tried the map() function and it also does not work, any reason why?

omikron · Answer 1 · 2016-03-01T14:43:39.677

2

In Python 3:

dict = {k: list(map(int, v)) for k, v in dict.items()}

edited Mar 01 '16 at 14:43

answered Mar 01 '16 at 10:51

omikron

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In the first row - I suppose it for Python 2 - you have a mistake. You should change it to something like `dict(((k, list(map(int, v))) for k, v in d.items()))` because Python 2 doesn't support dict generator – Andrii Rusanov Mar 01 '16 at 11:19
I was thinking about Python 2.7 which has it backported. I remove first row entirely since tags has `python` and most recent version that all should aim to work with is Python 3. – omikron Mar 01 '16 at 14:42

Andrii Rusanov · Accepted Answer · 2016-03-01T11:13:32.313

1

Because you don't overwrite actually values in your dictionary. Try to do:

for key,vals in dict.items():
    dict[key] = [int(s) for s in vals]

With dict comprehensions it looks much better, actually. I just tried to show what should be changed in your code.

edited Mar 01 '16 at 11:13

answered Mar 01 '16 at 10:48

Andrii Rusanov

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Correct way to change a list of strings to list of ints

2 Answers2