How to find the third latest date from a list of dates

Question

There is a list of dates in the form of array list Example : 11/02/2012 21/04/2019 12/03/2061 11/09/1961 22/08/2014

We will have to return the third latest date from the above list

I feel we will have to first sort in descending order of year and take the third latest date from that

Could you please give me a suggestions on this?

You are expected to attempt to solve the problem yourself before asking a question here. You already have a plan for a solution that might work, now you can just try to implement that. — apokryfos, Jul 15 '17 at 08:59
You have a list of what, exactly? `datetime` objects? Strings? — Aran-Fey, Jul 15 '17 at 09:03
You literally have to Google these three majestic words `"python datetime sort"` and let Google wind take you to learning land. — darksky, Jul 15 '17 at 09:05

score 3 · Answer 1 · edited Jul 18 '17 at 01:33

Is this the way you expect

>>> import datetime
>>> list = ['11/02/2012', '21/04/2019', '12/03/2061', '11/09/1961', '22/08/2014']
>>> d_list = [ datetime.datetime.strptime(d,'%d/%m/%Y') for d in list]
>>> d_list
[datetime.datetime(2012, 2, 11, 0, 0), datetime.datetime(2019, 4, 21, 0, 0), datetime.datetime(2061, 3, 12, 0, 0), datetime.datetime(1961, 9, 11, 0, 0), datetime.datetime(2014, 8, 22, 0, 0)]
>>> sorted(d_list)
[datetime.datetime(1961, 9, 11, 0, 0),
 datetime.datetime(2012, 2, 11, 0, 0),
 datetime.datetime(2014, 8, 22, 0, 0),
 datetime.datetime(2019, 4, 21, 0, 0),
 datetime.datetime(2061, 3, 12, 0, 0)]

score 1 · Answer 2 · answered Jul 15 '17 at 09:08

1

Assuming that you have datetime object in a list:

l = [list containing datetime objects]
l.sort()
l[2]

Should give you third latest date

answered Jul 15 '17 at 09:08

Rahul

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Mateen Ulhaq · Answer 3 · 2017-07-15T09:07:45.793

0

Without using the built in libraries, one way to do this is to:

Get the year, month, and date into a tuple. For instance, "11/02/2012" can be represented as (2012, 02, 11).
Run sort.
Retrieve the third latest date on the sorted list using sorted_dates[-3].

We can get the year, month, and date in the following way:

(d, m, y) = "11/02/2012".split('/')

Then, simply reverse the tuple, and run sort.

edited Jul 15 '17 at 09:07

answered Jul 15 '17 at 08:59

Mateen Ulhaq

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Assuming there isn't a year 2016 and a year 17. Datetimes are tricky. – darksky Jul 15 '17 at 09:01
This is not what OP has asked for. – Rahul Jul 15 '17 at 09:02
@Rahul Why not? I didn't give him the entire answer. Just a few hints. – Mateen Ulhaq Jul 15 '17 at 09:03
OP wants third latest date from list of dates. – Rahul Jul 15 '17 at 09:06
@Rahul That's just a simple `sorted_dates[-3]` from the list of sorted dates. This answer was more about how to sort the dates. – Mateen Ulhaq Jul 15 '17 at 09:08
Which is the reason not to use already available built-in libraries? It goes against one of the main good practices of programming: don't reinvent the wheel. Unless it is for educational purposes (and the OP doesnt seem to care about it). – Imanol Luengo Jul 15 '17 at 14:07
@ImanolLuengo I assumed it was for educational purposes. – Mateen Ulhaq Jul 15 '17 at 14:27

score 0 · Answer 4 · answered Jul 15 '17 at 09:08

So before working on dates you actually have to convert it into actual datetime object so simply do this:

from datetime import datetime


lst = ['11/02/2012' ,'21/04/2019' , '12/03/2061' , '11/09/1961' , '22/08/2014']
lstnew = []
for x in lst:
    lstnew.append(datetime.strptime(x, '%d/%m/%Y'))

now you can run the sort or find the max

for sorting the list use sorted(lstnew) for max use max(lstnew)

How to find the third latest date from a list of dates

4 Answers4