CODEWITHSUNDEEP
pythonlistsortingdictionarylambda
mat
mat

Reputation: 77

python sort dictionary list, of date strings

I have a list of dictionaries (from a JSON) containing date and time strings

[{"time": "17:00", "foo": "bar", "date": "01.02.20"}, {"time": "17:00", "foo": "bar", "date": "15.01.20"}, ...

The dates have the following format: %d.%m.%y, the times: %H:%M

my current code:

    def sortJSON(self, lis, dateKey, timeKey):
      if timeKey:
        return sorted(lis, key = lambda i: (i[dateKey], i[timeKey]))
      return sorted(lis, key = lambda i: i[dateKey])

However, since the dates are strings and of format %d.%m.%y they are not sorted correctly. Is there an elegant way of combining my current code with something like this:

Sort list of date strings

In other words, passing in an additional function to handle the values as dates?

Upvotes: 0

Views: 114

Answers (3)

TomG12
TomG12

Reputation: 21

def sortIt(key):
    from datetime import datetime
    thelist = [{"date": '30.10.2020'},
            {"date": '30.01.2020'},
            {"date": '30.06.2020'},
            {"date": '17.01.2012'},
            {"date": '25.04.2020'},
            {"date": '03.02.2016'}]
    # Unsorted
    print("-------Unsorted------")
    print(thelist)
    print("-------Sorted------")
    x = sorted(thelist, key = lambda i : datetime.strptime(i.get(key), "%d.%m.%Y"))
    print(x)

sortIt('date')

Upvotes: 0

blhsing
blhsing

Reputation: 106455

You can convert the dates to datetime.datetime objects for comparisons:

from datetime import datetime

def sortJSON(self, lis, dateKey, timeKey):
    return sorted(lis, key=lambda i: (datetime.strptime(i[dateKey], '%d.%m.%y'), i.get(timeKey)))

Upvotes: 2

marcos
marcos

Reputation: 4510

You were pretty close, you need to convert the string dates into datetime objects, so python can compare those objects according to time, this will work:

from datetime import datetime

d = [{"time": "17:00", "foo": "bar", "date": "01.02.20"}, {"time": "17:00", "foo": "bar", "date": "15.01.20"}]

sorted_dates = sorted(d, key=lambda date: datetime.strptime(date['time'] + ' ' + date['date'], '%H:%M %d.%m.%y'))
print(sorted_dates)

>>> [{'time': '17:00', 'foo': 'bar', 'date': '15.01.20'}, {'time': '17:00', 'foo': 'bar', 'date': '01.02.20'}]

Upvotes: 2

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