Hello! I have my data frame "mydata" (below) and data frame "reference" - that contains all the dates I would like to be present in the final data frame. I am trying to merge them so that the the result data frame contains all 8 dates in both subgroups (i.e., Group1 should have 8 rows and Group2 too). But when I merge it it's not coming out this way. Any hint would be greatly appreciated! Dimitri
mydata<-data.frame(mydate=rep(seq(as.Date("2008-12-29"), length = 8, by = "week"),2), group=c(rep("Group1",8),rep("Group2",8)),values=rnorm(16,1,1)) (reference);(mydata) set.seed(1234) out<-sample(1:16,5,replace=F) mydata<-mydata[-out,]; dim(mydata) (mydata) # "reference" contains the dates I want to be present in the final data frame: reference<-data.frame(mydate=seq(as.Date("2008-12-29"), length = 8, by = "week")) # Merging: new.data<-merge(mydata,reference,by="mydate",all.x=T,all.y=T) new.data<-new.data[order(new.data$group,new.data$mydate),] (new.data) # my new.data contains only 7 rows in Group 1 and 4 rows in Group 2 -- Dimitri Liakhovitski Ninah Consulting ______________________________________________ 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.