Finding the previous month

Question

I've seen some methods using dateutil module to do this, but is there a way to do this without just using the built in libs?

For example, the current month right now is July. I can do this using the datetime.now() function.

What would be the easiest way for python to return the previous month?

Answer 1

You can use the calendar module

>>> from calendar import  month_name, month_abbr
>>> d = datetime.now()
>>> month_name[d.month - 1] or month_name[-1]
'June'
>>> month_abbr[d.month - 1] or month_abbr[-1]
'Jun'
>>> 

Answer 2

If you just want it as a string then do below process.

import datetime
months =(" Blank", "December", "January", "February", "March", "April", 
 "May","June", "July","August","September","October","November")
d = datetime.date.today()
print(months[d.month])

Answer 3

Generalized function finding the year and month, based on a month delta:

# %% function
def get_year_month(ref_date, month_delta):
    year_delta, month_index = divmod(ref_date.month - 1 + month_delta, 12)
    year = ref_date.year + year_delta
    month = month_index + 1
    return year, month

# %% test
some_date = date(2022, 5, 31)
for delta in range(-12, 12):
    year, month = get_year_month(some_date, delta)
    print(f"{delta=}, {year=}, {month=}")

delta=-12, year=2021, month=5
delta=-11, year=2021, month=6
delta=-10, year=2021, month=7
delta=-9, year=2021, month=8
delta=-8, year=2021, month=9
delta=-7, year=2021, month=10
delta=-6, year=2021, month=11
delta=-5, year=2021, month=12
delta=-4, year=2022, month=1
delta=-3, year=2022, month=2
delta=-2, year=2022, month=3
delta=-1, year=2022, month=4
delta=0, year=2022, month=5
delta=1, year=2022, month=6
delta=2, year=2022, month=7
delta=3, year=2022, month=8
delta=4, year=2022, month=9
delta=5, year=2022, month=10
delta=6, year=2022, month=11
delta=7, year=2022, month=12
delta=8, year=2023, month=1
delta=9, year=2023, month=2
delta=10, year=2023, month=3
delta=11, year=2023, month=4