Hello Jim,
Many thanks for the feedback > Using "month" first advances the month without changing the day: if > this results in an invalid day of the month, it is counted forward > into the next month: see the examples. Indeed I missed the documentation of seq.Date that refers to seq.POSIXt. Many thanks for pointing this out. Still I would be tempted to count back the day into the same month instead of counting forward. But this behavior seems intentional and documented so no need to question it. > What is the problem that you are trying to solve? > Tell me what you want to do, not how you want to do it. The problem I'm trying to solve is this. for a date d and an integer m add.month(d,m) would Using "month" first advance the month without changing the day: if this results in an invalid day of the month, it is counted backward into the same month. so nearly the same behavior as seq.Date except add.month("2020-08-31",1) ==> 2020-09-30 add.month("2020-08-01",1) ==> 2020-09-01 Best regards, Jeremie ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.