Hi Dimitri, I have some doubts whether storing the results of a loop in a data frame and merging it with every run is the most efficient way of doing things, but I do not know your situation. This does what you want, I believe, but I suspect it could be quite slow. I worked around the placeholder issue using an if statement.
HTH, Josh for (i in 1:10) { x <- data.frame(a = 1, b = 2, c = i) if (i == 1) { y <- x } else { y <- merge(x, y, all.x = TRUE, all.y = TRUE) } } On Tue, Nov 9, 2010 at 8:42 AM, Dimitri Liakhovitski <dimitri.liakhovit...@gmail.com> wrote: > Hello! > > I am running a loop. The result of each run of the loop is a data > frame. I am merging all the data frames. > For exampe: > > The dataframe from run 1: > x<-data.frame(a=1,b=2,c=3) > > The dataframe from run 2: > y<-data.frame(a=10,b=20,d=30) > > What I want to get is: > merge(x,y,all.x=T,all.y=T) > > Then I want to merge it with the output of the 3rd run, etc. > > Unfortunately, I can't create the placeholder for the overall resutls > BEFORE I run the loop because I don't even know how many columns I'll > end up with - after merging all the data frames. > I was thinking of creating an empty list: > > first<-NULL > > ...and then updating it during each run by merging it with the data > frame that is the output of the run. However, when I try to merge the > empty list with any non-empty data frame - it ends up empty: > merge(first,a,,all.x=T,all.y=T) > > Is there a way to make it merge while keeping everything? > Thanks a lot! > -- > Dimitri Liakhovitski > Ninah Consulting > www.ninah.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. > -- Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.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.