Most recent previous business day in Python

Question

I need to subtract business days from the current date    I currently have some code which needs always to be running on the most recent business day  So that may be today if we re Monday thru Friday  but if it s Saturday or Sunday then I need to set it back to the Friday before the weekend  I currently have some pretty clunky code to do this    lastBusDay   datetime datetime today    if datetime date weekday lastBusDay     5        if it s Saturday      lastBusDay   lastBusDay - datetime timedelta days   1   then make it Friday  elif datetime date weekday lastBusDay     6        if it s Sunday      lastBusDay   lastBusDay - datetime timedelta days   2    then make it Friday   Is there a better way    Can I tell timedelta to work in weekdays rather than calendar days for example

User · Answer

If somebody is looking for solution respecting holidays (without any huge library like pandas), try this function:

import holidays
import datetime


def previous_working_day(check_day_, holidays=holidays.US()):
    offset = max(1, (check_day_.weekday() + 6) % 7 - 3)
    most_recent = check_day_ - datetime.timedelta(offset)
    if most_recent not in holidays:
        return most_recent
    else:
        return previous_working_day(most_recent, holidays)

check_day = datetime.date(2020, 12, 28)
previous_working_day(check_day)

which produce:

datetime.date(2020, 12, 24)

User · Answer

There seem to be several options if you re open to installing extra libraries   This post describes a way of defining workdays with dateutil   http   coding derkeiler com Archive Python comp lang python 2004-09 3758 html  BusinessHours lets you custom-define your list of holidays  etc   to define when your working hours  and by extension working days  are   http   pypi python org pypi BusinessHours

User · Answer

Maybe this code could help   lastBusDay   datetime datetime today   shift   datetime timedelta max 1  lastBusDay weekday     6    7 - 3   lastBusDay   lastBusDay - shift   The idea is that on Mondays yo have to go back 3 days  on Sundays 2  and 1 in any other day   The statement  lastBusDay weekday     6    7 just re-bases the Monday from 0 to 6   Really don t know if this will be better in terms of performance

User · Answer

If you want to skip US holidays as well as weekends  this worked for me  using pandas 0 23 3    import pandas as pd from pandas tseries holiday import USFederalHolidayCalendar from pandas tseries offsets import CustomBusinessDay US BUSINESS DAY   CustomBusinessDay calendar USFederalHolidayCalendar    july 5   pd datetime 2018  7  5  result   july 5 - 2   US BUSINESS DAY   2018-7-2   To convert to a python date object I did this   result to pydatetime   date

User · Answer

Why don t you try something like   lastBusDay   datetime datetime today   if datetime date weekday lastBusDay  not in range 0 5       lastBusDay   5

User · Answer

def getNthBusinessDay startDate  businessDaysInBetween       currentDate   startDate     daysToAdd   businessDaysInBetween     while daysToAdd  gt  0          currentDate    relativedelta days 1          day   currentDate weekday           if day  lt  5              daysToAdd -  1      return currentDate

User · Answer

This will give a generator of working days  of course without holidays  stop is datetime datetime object  If you need holidays just make additional argument with list of holidays and check with  IFology   -   def workingdays stop  start datetime date today         while start    stop          if start weekday    lt  5              yield start         start    datetime timedelta 1    Later on you can count them like  workdays   workingdays datetime datetime 2015  8  8   len list workdays

User · Answer

Use pandas  import datetime   BDay is business day  not birthday    from pandas tseries offsets import BDay  today   datetime datetime today   print today - BDay 4    Since today is Thursday  Sept 26  that will give you an output of  datetime datetime 2013  9  20  14  8  4  89761

User · Answer

timeboard package does this   Suppose your date is 04 Sep 2017  In spite of being a Monday  it was a holiday in the US  the Labor Day   So  the most recent business day was Friday  Sep 1    gt  gt  gt  import timeboard calendars US as US  gt  gt  gt  clnd   US Weekly8x5    gt  gt  gt  clnd  04 Sep 2017   rollback   to timestamp   date   datetime date 2017  9  1    In UK  04 Sep 2017 was the regular business day  so the most recent business day was itself    gt  gt  gt  import timeboard calendars UK as UK  gt  gt  gt  clnd   UK Weekly8x5    gt  gt  gt  clnd  04 Sep 2017   rollback   to timestamp   date   datetime date 2017  9  4    DISCLAIMER  I am the author of timeboard

User · Answer

DISCLAMER  I m the author     I wrote a package that does exactly this  business dates calculations  You can use custom week specification and holidays   I had this exact problem while working with financial data and didn t find any of the available solutions particularly easy  so I wrote one   Hope this is useful for other people   https   pypi python org pypi business calendar

User · Answer

Solution irrespective of different jurisdictions having different holidays   If you need to find the right id within a table  you can use this snippet  The Table model is a sqlalchemy model and the dates to search from are in the field day   def last relevant date db  Session  given date  date  - gt  int      available days    db query Table id  Table day                         order by desc Table day                          limit 100  all        close dates   pd DataFrame available days      close dates  delta     close dates  day   - given date     past dates    close dates                    loc close dates  delta    lt  pd Timedelta 0  unit  d         table id   int past dates loc past dates  delta   idxmax     id        return table id   This is not a solution that I would recommend when you have to convert in bulk  It is rather generic and expensive as you are not using joins  Moreover  it assumes that you have a relevant day that is one of the 100 most recent days in the model Table  So it tackles data input that may have different dates

User · Answer

another simplify version  lastBusDay   datetime datetime today   wk day   datetime date weekday lastBusDay  if wk day  gt  4        if it s Saturday or Sunday     lastBusDay   lastBusDay - datetime timedelta days   wk day-4   then make it Friday

[python] Most recent previous business day in Python

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