Thanks Gabor, that's what I understood but then why do I get these results?
library(zoo) 12*as.numeric(as.yearmon("2006-03-07")-as.yearmon("2006-02-07")) [1] NA Warning messages: 1: NAs introduced by coercion 2: NAs introduced by coercion 12*as.numeric(as.yearmon(2006-03-07)-as.yearmon(2006-02-07)) [1] -12 12*as.numeric(as.yearmon(as.Date("2006-03-07"))-as.yearmon(as.Date("2006-02-07"))) [1] 1 version _ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 2.1 year 2005 month 12 day 20 svn rev 36812 language R I am sure I am missing somehting, but what is it?? Thanks Francisco >From: "Gabor Grothendieck" <[EMAIL PROTECTED]> >To: "Francisco J. Zagmutt" <[EMAIL PROTECTED]> >CC: [EMAIL PROTECTED], r-help@stat.math.ethz.ch >Subject: Re: [R] difference between 2 dates: IN MONTHS the way >Motherscompute it >Date: Fri, 10 Mar 2006 21:01:55 -0500 > >as.yearmon has a character method so its not necessary to >convert it to Date first: > > > print(as.yearmon.character) >function (x, ...) >as.yearmon(as.Date(x, ...)) > >On 3/10/06, Francisco J. Zagmutt <[EMAIL PROTECTED]> wrote: > > 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