On Tue, Mar 13, 2012 at 11:27 AM, aledanda <danda.ga...@gmail.com> wrote: > Dear All, > > I hope you don't mind helping me with this small issue. I haven't been using > R in years and I'm trying to fill in a matrix > with the output of a function (I'm probably using the Matlab logic here and > it's not working). > Here is my code: > > for (i in 1:length(input)){ > out[i,1:3] <- MyFunction(input[i,1],input[i,2], input[i,3]) > out[i,4:6] <- MyFunction(input[i,5],input[i,7], input[i,6]) > out[i,7:9] <- MyFunction(input[i,8],input[i,10], input[i,9]) > } > > 'input' is a matrix >> dim(input) > [1] 46 10 > > and each raw corresponds to a different subject. > The error I get here is > > /Error in out[i, 1:3] <- get.vaTer(input[i, 2], input[i, 4], input[i, 3], : > object 'out' not found/
out has to exist first, as previous commenter said. Furthermore, suggestions: Consider making MyFunction accept a vector of 3 arguments, rather than separate arguments. Consider making out 3 columns, as in out <- matrix(0, nrow=N, ncol=3) for(i ...){ out[i,1:3] <- MyFunction(input[i,1:3]) out[i,1:3] <- MyFunction(input[i,4:6]) out[i,1:3] <- MyFunction(input[i,7:9]) } If you could re-shape your input "thing" as a list with one element that needs to go into MyFunction, this could get easier still: lapply(input, MyFunction) or if input were an array with 3 columns, you could revise MyFuntion to accept a 3-vector. apply(input, 1, MyFunction) Hardly ever in R does one need to specify inputs as you have done in your example. pj -- Paul E. Johnson Professor, Political Science Assoc. Director 1541 Lilac Lane, Room 504 Center for Research Methods University of Kansas University of Kansas http://pj.freefaculty.org http://quant.ku.edu ______________________________________________ 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.