Add X days to a Datetime Series

Question

I have a Datetime Series that always contains the datetime of yesterday like:

Series: '' [datetime[ns]]
[
    2024-08-29 00:00:00
]

How can I add 2 days to that Datetime Series so that I can add the datetime from 2 days and 3 days ago?

End result should be:

Series: '' [datetime[ns]]
[
    2024-08-29 00:00:00
    2024-08-28 00:00:00
    2024-08-27 00:00:00
]

Answer 1

pl.date_range can be used along with pl.Series.dt.offset_by to create the start date.

pl.date_range(dates.dt.offset_by("-2d"), dates, eager=True)

shape: (3,)
Series: 'dates' [date]
[
    2024-08-27
    2024-08-28
    2024-08-29
]

If the series is required in decreasing order, one can subsequently reverse the series using pl.Series.reverse.

pl.date_range(dates.dt.offset_by("-2d"), dates, eager=True).reverse()