Hi William, Glad to know that. So, I guess "difftime()" did the trick if both befong to the class "Date".
A.K. ________________________________ From: William Mabe <billm...@gmail.com> To: arun <smartpink...@yahoo.com> Sent: Thursday, July 12, 2012 1:12 PM Subject: Re: [R] unable to subtract dates in R Thanks Arun! That worked. On Wed, Jul 11, 2012 at 8:17 PM, arun <smartpink...@yahoo.com> wrote: Hi, > >It is a bit difficult to give suggestions when there are no example datasets. >Have you checked whether both belong to "Date" class? > >You could use, >difftime(intakeDS$DOB, intakeDS$IntakeDate_d,units="days") >to get the difference between dates >A.K. > > > > > >----- Original Message ----- >From: William Mabe <billm...@gmail.com> >To: r-help@r-project.org >Cc: >Sent: Wednesday, July 11, 2012 6:20 PM >Subject: [R] unable to subtract dates in R > >Hi, > >I wanted to calculate the age of people in my dataset by subtracting the >individual's date of birth from their intake into a program. > >After several hours, searches of help archives, and the downloading of >lubiridate, I have had no luck with this. > >Below is the code I used. > >> intakeDS$DOB <- as.character(intakeDS$DOB) > >> intakeDS$DOB <- as.Date(intakeDS$DOB, "%Y%m%d") > >> > >> # Make IntakeDate a date variable, by first converting it from numeric to >character then from character to date > >> #intakeDS$IntakeDate <- as.character(intakeDS$IntakeDate) > >> intakeDS$IntakeDate_d <- as.Date(intakeDS$IntakeDate_c, "%Y%m%d") > >> > >> intakeDS$intake_age <- intakeDS$DOB - intakeDS$IntakeDate_d > >> intakeDS$intake_age > >Time differences in days > > [1] NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA > >[61] NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA > >[121] NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA > >[181] NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA NA >NA NA NA NA NA NA NA NA NA NA NA NA > >[241] NA NA NA NA NA NA NA > > >I also downloaded the lubridate package and used the new_interval command >and that created a variable that showed the start date and the end date. >However, I was not able to subtract one date from the other to calculate an >age variable. > > >Any help would be greatly appreciated as this has been a pretty miserable >afternoon hacking away at this. > > >Thanks, > >Bill > > > [[alternative HTML version deleted]] > >______________________________________________ >R-help@r-project.org mailing list >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. > > ______________________________________________ R-help@r-project.org mailing list 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.