Re-read ?"[" (always better to read the docs before archives...) and note in particular:
"[[ can be applied recursively to lists, so that if the single index i is a vector of length p, alist[[i]] is equivalent to alist[[i1]]...[[ip]] providing all but the final indexing results in a list." I agree -- it's terse. But it's accurate and complete. -- Bert On Thu, Mar 7, 2013 at 12:14 PM, Jeff Hollenbeck <holl...@peak.org> wrote: > Dear R Users. > > This seems like a simple task, but I'm stuck. > > I have a list with 3 elements: (2 vectors and 1 matrix). I wish to extract > each of these data elements using index subscripts and multiply them with a > vector multiplier. > > What I have: >> betas > [1] 0.01 0.01 0.01 > >> LData[1] > $int > [1] 1 1 1 1 1 1 1 1 1 1 > $date > [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10] > [1,] 152 153 154 155 156 157 158 159 160 161 > [2,] 163 164 165 166 167 168 162 163 164 165 > $land > [1] 0 0 0 0 1 0 1 1 0 0 > > What I'm trying to do: > I would like to have the elements in the vector, betas[1:3] multiplied by > corresponding data elements in LData[[1:3]]. > This is how I initially try to do it, but does not work: > >> probs <- betas[1:3] * LData[[1:3]] > Error in LData[[1:3]] : recursive indexing failed at level 2 > > Apparently, the above is not allowed. But, if I try > >> probs <- betas[1:3] * LData[1:3] > Error in betas[1:3] * LData[1:3] : > non-numeric argument to binary operator > > I can see that the list keys get in the way of the multiplication operation. > > There just has to be a way to do this. I have searched archives and find > plenty of examples of extracting data elements individually, and even > extraction of multiple vector elements (unfortunately one of mine is an > matrix), but not my situation. In particular, no examples attempting to > vectorize the math operation. yapply and mapply don't seem to be what I > want, but what I've read of them confuses me. Want to avoid for loops, > unless its the only way. > > All help is much appreciated! > > Thanks. > > ******************************************************************* > Jeff P. Hollenbeck > USGS Forest and Rangeland Ecosystem Science Center > 3200 SW Jefferson Way > Corvallis, OR 97331 > 541-750-0966 > > [[alternative HTML version deleted]] > > ______________________________________________ > 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. -- Bert Gunter Genentech Nonclinical Biostatistics Internal Contact Info: Phone: 467-7374 Website: http://pharmadevelopment.roche.com/index/pdb/pdb-functional-groups/pdb-biostatistics/pdb-ncb-home.htm ______________________________________________ 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.
