I have been trying to change the following format of time 8.25 (fractional hours) to 8.15 meaning 8:15. And 17.75 to 17.45 meaning 17:45. The problem is that I specifically need that format (timedelta) e.g 17.45 with a point . instead of :.

This can be done conveniently by using the appropriate representation for your fractional hours, namely a timedelta. If the input is of datatype string, convert to float first.

Ex:

from datetime import datetime, timedeltafor td in [8.25, 17.75]:# add the duration as timedelta to an arbitrary date to get a time object:print((datetime(2020,1,1) + timedelta(hours=td)).time())

08:15:00
17:45:00

Using pandas, that could look like

import pandas as pds = pd.Series([8.25, 17.75])refDate = '2020-01-01' # need a date..t = pd.Timestamp(refDate) + pd.to_timedelta(s, unit='h')print(t)# 0   2020-01-01 08:15:00
# 1   2020-01-01 17:45:00
# dtype: datetime64[ns]print(t.dt.time)# 0    08:15:00
# 1    17:45:00
# dtype: object