Is there a simple way to increment a datetime object one month in Python

Question

So I am trying to find a way to increment a datetime object by one month  However  it seems this is not so simple  according to this question    I was hoping for something like    import datetime as dt  now   dt datetime now   later   now   dt timedelta months 1    But that doesn t work  I was also hoping to be able to go to the same day  or the closest alternative  in the next month if possible  For example  a datetime object set at January 1st would increment to Feb 1st whereas a datetime object set at February 28th would increment to March 31st as opposed to March 28th or something     To be clear  February 28th would  typically  map to March 31st because it is the last day of the month  and thus it should go to the last day of the month for the next month  Otherwise it would be a direct link  the increment should go to the day in the next month with the same numbered day     Is there a simple way to do this in the current release of Python

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Question  Is there a simple way to do this in the current release of Python   Answer  There is no simple  direct  way to do this in the current release of Python   Reference  Please refer to docs python org 2 library datetime html  section 8 1 2  timedelta Objects  As we may understand from that  we cannot increment month directly since it is not a uniform time unit   Plus  If you want first day -  first day and last day -  last day mapping you should handle that separately for different months

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gt  gt  gt  now datetime datetime 2016  1  28  18  26  12  980861   gt  gt  gt  later   now replace month now month 1   gt  gt  gt  later datetime datetime 2016  2  28  18  26  12  980861    EDIT  Fails on  y   datetime date 2016  1  31   y replace month 2  results in ValueError  day is out of range for month   Ther is no simple way to do it  but you can use your own function like answered below

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Check out from dateutil relativedelta import   for adding a specific amount of time to a date  you can continue to use timedelta for the simple stuff i e  use date   use date   datetime timedelta minutes  10  use date   use date   datetime timedelta hours  1  use date   use date   datetime timedelta days  1  use date   use date   datetime timedelta weeks  1   or you can start using relativedelta use date   use date relativedelta months  1   use date   use date relativedelta years  1   for the last day of next month  use date   use date relativedelta months  1  use date   use date relativedelta day 31   Right now this will provide 29 02 2016 for the penultimate day of next month  use date   use date relativedelta months  1  use date   use date relativedelta day 31  use date   use date relativedelta days -1   last Friday of the next month  use date   use date relativedelta months  1  day 31  weekday FR -1    2nd Tuesday of next month  new date   use date relativedelta months  1  day 1  weekday TU 2    As  mrroot5 points out dateutil s rrule functions can be applied  giving you an extra bang for your buck  if you require date occurences  for example  Calculating the last day of the month for 9 months from the last day of last month  Then  calculate the 2nd Tuesday for each of those months  from dateutil relativedelta import   from dateutil rrule import   from datetime import datetime use date   datetime 2020 11 21    Calculate the last day of last month use date   use date relativedelta months -1  use date   use date relativedelta day 31    Generate a list of the last day for 9 months from the calculated date x   list rrule freq MONTHLY  count 9  dtstart use date  bymonthday  -1     print  quot Last day quot   for ld in x      print ld    Generate a list of the 2nd Tuesday in each of the next 9 months from the calculated date print  quot  n2nd Tuesday quot   x   list rrule freq MONTHLY  count 9  dtstart use date  byweekday TU 2    for tuesday in x      print tuesday   Last day 2020-10-31 00 00 00 2020-11-30 00 00 00 2020-12-31 00 00 00 2021-01-31 00 00 00 2021-02-28 00 00 00 2021-03-31 00 00 00 2021-04-30 00 00 00 2021-05-31 00 00 00 2021-06-30 00 00 00  2nd Tuesday 2020-11-10 00 00 00 2020-12-08 00 00 00 2021-01-12 00 00 00 2021-02-09 00 00 00 2021-03-09 00 00 00 2021-04-13 00 00 00 2021-05-11 00 00 00 2021-06-08 00 00 00 2021-07-13 00 00 00  This is by no means an exhaustive list of what is available  Documentation is available here  https   dateutil readthedocs org en latest

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Note  This answer shows how to achieve this using only the datetime and calendar standard library  stdlib  modules - which is what was explicitly asked for  The accepted answer shows how to better achieve this with one of the many dedicated non-stdlib libraries  If you can use non-stdlib libraries   by all means do so for these kinds of date time manipulations   How about this   def add one month orig date         advance year and month by one month     new year   orig date year     new month   orig date month   1       note  in datetime date  months go from 1 to 12     if new month  gt  12          new year    1         new month -  12      new day   orig date day       while day is out of range for month  reduce by one     while True          try              new date   datetime date new year  new month  new day          except ValueError as e              new day -  1         else              break      return new date   EDIT   Improved version which    keeps the time information if given a datetime datetime object doesn t use try catch  instead using calendar monthrange from the calendar module in the stdlib      import datetime import calendar  def add one month orig date         advance year and month by one month     new year   orig date year     new month   orig date month   1       note  in datetime date  months go from 1 to 12     if new month  gt  12          new year    1         new month -  12      last day of month   calendar monthrange new year  new month  1      new day   min orig date day  last day of month       return orig date replace year new year  month new month  day new day

[python] Is there a simple way to increment a datetime object one month in Python?

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