accounting_month.py

import pandas as pd

def accounting_month(start, end):
    month_end = pd.date_range(start=start, end=end, freq=pd.tseries.offsets.LastWeekOfMonth(n=1, weekday=6))
    month_start = month_end.shift(periods=-1, freq=pd.tseries.offsets.LastWeekOfMonth(n=1, weekday=6)).shift(periods=1, freq='D')
    weeks_in_month = (month_end - month_start).shift(periods=1, freq='D') / pd.Timedelta(7, 'D')
    return pd.DataFrame({'start': month_start, 'end': month_end}, index=month_end.to_period('M'))
  
  if __name__ == '__main__':
    accounting_calendar = accounting_month('2019-01-01', '2022-01-01')
    print(accounting_calendar['Jan 2020'])
    print(accounting_calendar)