Recode continuous number into continuous dates in Python

Question

I have a variable looks like

1,1,1,1, 2,2,2,3,3,3,3,3,4,4,5,6,6,6, ,.....100,100,100

I would like to recode them into dates
1=31.12.2020
2=30.12.2020
3=29.12.2020
...

In my real case, there will be more than 1000 dates (or more) to be recoded and also have to consider the leap year.

appreciate if there is an elegant way to deal with it by python pandas.

Thank you very much for helping a beginner.

`pd.TimeStamp('2021/01/01')-pd.to_timedelta(list_of_variable, units='D')` — Quang Hoang, Apr 01 '21 at 13:19

score 2 · Accepted Answer · answered Apr 01 '21 at 13:19

Pandas has a "date_range" method that can return a sequence of regularly spaced date objects based on a start date, an ~'increment', and an end date. You could use this to build a sequence of dates spaced by single days, and then use that to associate each of those indexes (1,1,1,2,2,...) with a date object in the date_range sequence.

pandas date_range docs

score 1 · Answer 2 · answered Apr 01 '21 at 13:25

you can create a simple dictionary using pd.date_range and pd.DateOffset

range_var = list(range(1000))
end_date = pd.Timestamp('31.12.2020') 

date_dict = dict(zip(range_var[::-1], #reverse the list.
         pd.date_range(
         end_date - pd.DateOffset(days=max(range_var)),
         end_date,
         freq='D'
            )
        )
    )



df = pd.DataFrame.from_dict(date_dict,orient='index').sort_index()


             0
0   2020-12-31
1   2020-12-30
2   2020-12-29
3   2020-12-28
4   2020-12-27
..         ...
995 2018-04-11
996 2018-04-10
997 2018-04-09
998 2018-04-08
999 2018-04-07

Recode continuous number into continuous dates in Python

2 Answers2