Use write.table. Write.csv follows a very specific definition for csv... one element of which is that it is not allowed to have a second header line after data lines. The only way for write.csv to enforce this is to disallow appending.
On June 4, 2020 6:34:14 PM PDT, Erin Hodgess <erinm.hodg...@gmail.com> wrote: > Hello! > >Hope everyone is doing as well as possible. > >I have a question about write.csv. I thought that the append argument >would permit adding another data frame with the same column names. > >Here is my example: > > date1 <- as.Date("2020-03-09") > wday <- weekdays(date1) > x1 <- data.frame(date=date1,day=wday,lev=1:5,y=rnorm(5)) > x1 > date day lev y >1 2020-03-09 Monday 1 -0.09543049 >2 2020-03-09 Monday 2 0.53943428 >3 2020-03-09 Monday 3 -0.79224851 >4 2020-03-09 Monday 4 0.68168147 >5 2020-03-09 Monday 5 -1.02902897 > write.csv(file="test1.csv",x1,row.names=FALSE) > date1 <- date1 + 1 > wday <- weekdays(date1) > x2 <- data.frame(date=date1,day=wday,lev=1:5,y=rnorm(5)) > x2 > date day lev y >1 2020-03-10 Tuesday 1 -0.6648301 >2 2020-03-10 Tuesday 2 -0.1137580 >3 2020-03-10 Tuesday 3 1.6532675 >4 2020-03-10 Tuesday 4 -0.5845293 >5 2020-03-10 Tuesday 5 0.2849392 > write.csv(file="test1.csv",x2,row.names=FALSE,append=TRUE) >Warning message: >In write.csv(file = "test1.csv", x2, row.names = FALSE, append = TRUE) >: > attempt to set 'append' ignored > >The values from x2 appear in the test1.csv file. > >What am I missing, please? > >Thanks, >Erin > > >Erin Hodgess, PhD >mailto: erinm.hodg...@gmail.com > > [[alternative HTML version deleted]] > >______________________________________________ >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. -- Sent from my phone. Please excuse my brevity. ______________________________________________ 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.