Converting integer values to week (year-week format)

I am trying to convert one of the dataframes I have to year-week format to use it in my time series modeling, but I am not sure how would I be able to do this?

Here is my code:

import pandas as pd
import numpy as np
c=15
s={'week':[1,2,3,4,5,6,7,8],'Sales':[10,20,30,40,50,60,70,80]}
p=pd.DataFrame(data=s)

Output-

Desired O/p in week column should be in date time format.

The datatype was an int in the 1st dataframe, but needs to be in datetime, where 2021 is year and 1 is week. (1st week of year 2021) How would I be able to do this?

Answer

You can use .apply():

import datetime
p['week'] = p['week'].apply(
    lambda x: datetime.datetime.strptime(f'2021-{x:02}-1', '%Y-%W-%u')
)

This outputs:

        week  Sales
0 2021-01-04     10
1 2021-01-11     20
2 2021-01-18     30
3 2021-01-25     40
4 2021-02-01     50
5 2021-02-08     60
6 2021-02-15     70
7 2021-02-22     80