Gabor, please correct me if I am wrong but shouldn't you use as.Date to change the date string to a "Date" class before you call as.yearmon? i.e.
12* as.numeric(as.yearmon(as.Date("2006-03-07"))-as.yearmon(as.Date("2006-02-07"))) That returns 1 in Windows XP Regards Francisco >From: "Gabor Grothendieck" <[EMAIL PROTECTED]> >To: "Smith, Phil" <[EMAIL PROTECTED]> >CC: r-help@stat.math.ethz.ch >Subject: Re: [R] difference between 2 dates: IN MONTHS the way >Motherscompute it >Date: Fri, 10 Mar 2006 13:38:12 -0500 > >zoo has the "yearmon" class which will convert a date to a year + >0/12 to 11/12 to represent the month, disregarding the day, so: > >library(zoo) >12 * as.numeric((as.yearmon("2006-03-07") - as.yearmon("2006-02-06"))) # 1 > >On 3/10/06, Smith, Phil <[EMAIL PROTECTED]> wrote: > > Hi R-people: > > > > I need a function to compute the number of months between 2 dates, in >the same way a mother would do it. > > > > For example, if a kid is born on February 6, the number of months >between that date and March 7 is exactly 1 month, although it is only 29 >days. > > > > Thank you! > > Phil Smith > > CDC > > > > > > > > > > [[alternative HTML version deleted]] > > > > ______________________________________________ > > R-help@stat.math.ethz.ch mailing list > > https://stat.ethz.ch/mailman/listinfo/r-help > > PLEASE do read the posting guide! >http://www.R-project.org/posting-guide.html > > > >______________________________________________ >R-help@stat.math.ethz.ch mailing list >https://stat.ethz.ch/mailman/listinfo/r-help >PLEASE do read the posting guide! >http://www.R-project.org/posting-guide.html ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html