How to sort a column in a dataframe containing a list of dates?

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I have a dataframe containing a column id associated with a column containing a list of dates. These columns can contain 1 or more dates, but they are not sorted. How can I sort each row of the column dates chronologically?

data = [
    [
        1,
        [
            "2017-12-06",
            "2017-12-05",
            "2017-12-06",
            "2018-01-03",
            "2018-01-04",
            "2017-11-24",
        ],
    ],
    [
        2,
        [
            "2017-12-06",
            "2017-12-05",
            "2017-12-06",
            "2019-01-03",
        ],
    ],
]
df = pd.DataFrame(data, columns=["id", "dates"])
df


id  dates
1   [2017-12-06, 2017-12-05, 2017-12-06, 2018-01-03, 2018-01-04, 2017-11-24]
2   [2017-12-06, 2017-12-05, 2017-12-06, 2019-01-03]

what I want (dates sorted chronologically):

id  dates
1   [2017-11-24, 2017-12-05, 2017-12-06, 2018-01-03, 2018-01-04]
2   [2017-12-05, 2017-12-06, 2019-01-03]

what I've tried (that has not worked):

f = lambda x: x.sort(key=lambda date: datetime.strptime(date, "%Y-%m-%d"))
df["dates"].apply(f)

(this returns all None)

pandas dataframe date sorting python
1 Answers

Try to sort the lists in-place:

df["dates"].apply(list.sort)
print(df)

Prints:

   id                                                                     dates
0   1  [2017-11-24, 2017-12-05, 2017-12-06, 2017-12-06, 2018-01-03, 2018-01-04]
1   2                          [2017-12-05, 2017-12-06, 2017-12-06, 2019-01-03]
user_100359850
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