I've only tried
from datetime import datetime
my_dates = ['5-Nov-18', '25-Mar-17', '1-Nov-18', '7 Mar 17']
my_dates.sort(key=lambda date: datetime.strptime(date, "%d-%b-%y"))
print(my_dates)
But how can I make this work for date formats like
my_dates = ['05 Nov 2018', '25 Mar 2017', '01 Nov 2018', '07 Mar 2017']
One inelegant solution which comes to mind is replacing all spaces with dashes as shown below:
from datetime import datetime
my_dates = ['5-Nov-18', '25-Mar-17', '1-Nov-18', '7 Mar 17']
my_dates.sort(key=lambda date: datetime.strptime(date.replace(' ', '-'), "%d-%b-%y"))
print(my_dates)
If all you're looking is the specific set of dates you have provided, just change up the format in strptime():
my_dates = ['05 Nov 2018', '25 Mar 2017', '01 Nov 2018', '07 Mar 2017']
my_dates.sort(key=lambda date: datetime.strptime(date, "%d %b %Y"))
# Change the last %y to %Y
However, if you have varying date formats in your list, you could prepare a list of possibly anticipated string formats and define your own function to parse against each format:
def func(date, formats):
for frmt in formats:
try:
str_date = datetime.strptime(date, frmt)
return str_date
except ValueError:
continue
# might want to consider handling a scenario when nothing is returned
my_formats = ['%d-%b-%y', '%d %b %y', '%d %b %Y']
my_dates = ['5-Nov-18', '25-Mar-17', '1-Nov-18', '7 Mar 17', '05 Nov 2018', '25 Mar 2017', '01 Nov 2018', '07 Mar 2017']
my_dates.sort(key=lambda date: func(date, my_formats))
print(my_dates)
# ['7 Mar 17', '07 Mar 2017', '25-Mar-17', '25 Mar 2017', '1-Nov-18', '01 Nov 2018', '5-Nov-18', '05 Nov 2018']
The caveat here is if an unanticipated date format shows up, the function will return None so it won't be sorted properly. If that's a concern, you might want to add some handling at the end of the func() when all parsing attempts failed. Some devs might also say to avoid try...except..., but I can only come up with this way.
dates can be sorted once it's a datetime object
my_dates = ['05 Nov 2018', '25 Mar 2017', '01 Nov 2018', '07 Mar 2017']
my_dates = [ dt.strptime(date, '%d %b %Y') for date in my_dates ]
print(my_dates)
# [datetime.datetime(2018, 11, 5, 0, 0), datetime.datetime(2017, 3, 25, 0, 0), datetime.datetime(2018, 11, 1, 0, 0), datetime.datetime(2017, 3, 7, 0, 0)]
my_dates.sort()
print(my_dates)
# [datetime.datetime(2017, 3, 7, 0, 0), datetime.datetime(2017, 3, 25, 0, 0), datetime.datetime(2018, 11, 1, 0, 0), datetime.datetime(2018, 11, 5, 0, 0)]
my_dates = [ date.strftime('%d %b %Y') for date in my_dates ]
print(my_dates)
# ['07 Mar 2017', '25 Mar 2017', '01 Nov 2018', '05 Nov 2018']
