Thanks for the help!
> a.df[1:10,c(1,6,9)] DATE DEATH DEATH1 1207 2009-04-16 2009-05-06 20 days 1514 2009-04-16 2009-05-06 20 days 2548 2009-04-16 2009-05-08 22 days 3430 2009-04-16 2009-05-09 23 days 3851 2009-04-16 2009-05-09 23 days 3945 2009-04-16 2009-05-09 23 days 7274 2009-04-16 2009-05-12 26 days 7532 2009-04-16 2009-05-12 26 days 7651 2009-04-16 2009-05-12 26 days 8495 2009-04-16 2009-05-13 27 days > 2010/6/20 Christos Argyropoulos <argch...@hotmail.com>: > Hi, > Are you sure these are date objects and not strings? For example > >> d1<-runif(10,0,100) >> d2<-runif(10,0,200) >> df<-data.frame(d1=d1+as.Date("2010-6-20")+d1,d2=as.Date("2009-6-20")+d2) >> df > d1 d2 > 1 2010-09-23 2009-06-30 > 2 2010-06-25 2009-08-21 > 3 2010-10-10 2009-08-04 > 4 2010-07-06 2009-07-30 > 5 2010-07-05 2009-10-19 > 6 2010-07-07 2009-08-01 > 7 2010-11-09 2009-09-25 > 8 2010-07-19 2009-12-03 > 9 2010-12-24 2009-07-19 > 10 2010-09-25 2009-06-27 >> df$DD<-df$d1-df$d2 >> df > d1 d2 DD > 1 2010-09-23 2009-06-30 449.7866 days > 2 2010-06-25 2009-08-21 307.0807 days > 3 2010-10-10 2009-08-04 431.7428 days > 4 2010-07-06 2009-07-30 341.2171 days > 5 2010-07-05 2009-10-19 259.0490 days > 6 2010-07-07 2009-08-01 339.7433 days > 7 2010-11-09 2009-09-25 410.1609 days > 8 2010-07-19 2009-12-03 227.1901 days > 9 2010-12-24 2009-07-19 523.5030 days > 10 2010-09-25 2009-06-27 454.6529 days > > generates differences between the 2 columns without NAs. > What's the output you get when you call str on your data frame? > > Christos > > >> Date: Sun, 20 Jun 2010 19:13:24 -0500 >> From: erinm.hodg...@gmail.com >> To: r-h...@stat.math.ethz.ch >> Subject: [R] difference in dates >> >> Dear R People: >> >> I have a data frame with the two following date columns: >> >> >> > a.df[1:10,c(1,6)] >> DATE DEATH >> 1207 2009-04-16 2009-05-06 >> 1514 2009-04-16 2009-05-06 >> 2548 2009-04-16 2009-05-08 >> 3430 2009-04-16 2009-05-09 >> 3851 2009-04-16 2009-05-09 >> 3945 2009-04-16 2009-05-09 >> 7274 2009-04-16 2009-05-12 >> 7532 2009-04-16 2009-05-12 >> 7651 2009-04-16 2009-05-12 >> 8495 2009-04-16 2009-05-13 >> > >> >> I would like to generate a 3rd column which is the difference in days >> between the two dates. >> >> I tried >> >> a.df$DEATH - a.df$DATE >> >> but I obtain all NA. >> >> Any help would be much appreciated. >> >> Thanks, >> Erin >> >> >> >> -- >> Erin Hodgess >> Associate Professor >> Department of Computer and Mathematical Sciences >> University of Houston - Downtown >> mailto: erinm.hodg...@gmail.com >> >> ______________________________________________ >> 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. > > ________________________________ > Hotmail: Powerful Free email with security by Microsoft. Get it now. -- Erin Hodgess Associate Professor Department of Computer and Mathematical Sciences University of Houston - Downtown mailto: erinm.hodg...@gmail.com ______________________________________________ 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.