Hi, I want to apply a custom function to all the elements of one matrix. The function uses the value in the same i,j in a second matrix. How can I use apply() or similar function to avoid nested loops in i and j? Thanks, Scott Waichler Pacific Northwest National Laboratory Richland, WA, USA
Hi Scott, You could set up a three-dimensional array and then use apply on the desired dimension (MARGIN in apply language). HTH! Many thanks, Ranjan On Wed, 30 Apr 2014 17:54:48 +0000 "Waichler, Scott R" <Scott.Waichler at pnnl.gov> wrote:> Hi, > > I want to apply a custom function to all the elements of one matrix. The function uses the value in the same i,j in a second matrix. How can I use apply() or similar function to avoid nested loops in i and j? > > Thanks, > Scott Waichler > Pacific Northwest National Laboratory > Richland, WA, USA > > ______________________________________________ > R-help at 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. >-- Important Notice: This mailbox is ignored: e-mails are set to be deleted on receipt. Please respond to the mailing list if appropriate. For those needing to send personal or professional e-mail, please use appropriate addresses. ____________________________________________________________ FREE 3D EARTH SCREENSAVER - Watch the Earth right on your desktop!
Scott: Your problem specification is rather vague: What do you mean by "use"? In general, matrices are merely vectors with a dim attribute, so if you can do what you want with them as vectors, then that will work for them as matrices. For example:> m1<- matrix(1:6, nr=3) > m2 <- matrix(11:16, nr=2) > m2*m2[,1] [,2] [,3] [1,] 121 169 225 [2,] 144 196 256 If this does not meet your needs, you will have to follow the posting guide and provide both code and a minimal reproducible example. Cheers, Bert Bert Gunter Genentech Nonclinical Biostatistics (650) 467-7374 "Data is not information. Information is not knowledge. And knowledge is certainly not wisdom." H. Gilbert Welch On Wed, Apr 30, 2014 at 10:54 AM, Waichler, Scott R <Scott.Waichler at pnnl.gov> wrote:> Hi, > > I want to apply a custom function to all the elements of one matrix. The function uses the value in the same i,j in a second matrix. How can I use apply() or similar function to avoid nested loops in i and j? > > Thanks, > Scott Waichler > Pacific Northwest National Laboratory > Richland, WA, USA > > ______________________________________________ > R-help at 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.