Sort a list of dictionaries of dates by value-CodePudding

I'm trying to sort the values with current year.

Current year values should show first.

mdlist = [{0:'31 Jan 2022', 1:'', 2:'10 Feb 2022'},
          {0:'10 Feb 2021', 1:'20, Feb 2021', 2:''}, 
          {0:'10 Feb 2022', 1:'10 Feb 2022', 2:'10 Feb 2022'}]

mdlist = sorted(mdlist, key=lambda d:d[0])

but it is not working as expected

expected output:

mdlist = [{0:'31 Jan 2022', 1:'', 2:'10 Feb 2022'},
          {0:'10 Feb 2022', 1:'10 Feb 2022', 2:'10 Feb 2022'},
          {0:'10 Feb 2021', 1:'20 Feb 2021', 2:''}]

CodePudding user response：

Maybe you could leverage the fact that these are datetimes by using the datetime module and sort it by the years in descending order and the month-days in ascending order:

from datetime import datetime
def sorting_key(dct):
    ymd = datetime.strptime(dct[0], "%d %b %Y")
    return -ymd.year, ymd.month, ymd.day

mdlist.sort(key=sorting_key)

Output:

[{0: '31 Jan 2022', 1: '', 2: '10 Feb 2022'},
 {0: '10 Feb 2022', 1: '10 Feb 2022', 2: '10 Feb 2022'},
 {0: '10 Feb 2021', 1: '20 Feb 2021', 2: ''}]

CodePudding user response：

Use a key function that returns 0 if the year is 2022, 1 otherwise. This will sort all the 2022 dates first.

firstyear = '2022'
mdlist = sorted(mdlist, key=lambda d: 0 if d:d[0].split()[-1] == firstyear else 1)