Dear R-List, thank you very much for the fast answers. Andy Liaw and James Holtman both gave me some example code which does exactly what I want.
I will now try to check which one is better suited for my actual matrix (in terms of speed). Thanks, Roland -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Sent: Friday, January 21, 2005 3:57 PM To: Rau, Roland Cc: [email protected]; [EMAIL PROTECTED] Subject: Re: [R] Avoiding a Loop? Does this do what you want? nr.of.columns <- 4 myconstant <- 27.5 mymatrix <- matrix(myconstant, nrow=5, ncol=nr.of.columns) mymatrix[,1] <- 1:5 t(apply(mymatrix, 1, function(x) cumprod(x))) __________________________________________________________ James Holtman "What is the problem you are trying to solve?" Executive Technical Consultant -- Office of Technology, Convergys [EMAIL PROTECTED] +1 (513) 723-2929 "Rau, Roland" <[EMAIL PROTECTED]> To: <[email protected]> Sent by: cc: [EMAIL PROTECTED] Subject: [R] Avoiding a Loop? ath.ethz.ch 01/21/2005 07:31 Dear R-Helpers, I have a matrix where the first column is known. The second column is the result of multiplying this first column with a constant "const". The third column is the result of multiplying the second column with "const"..... So far, I did it like this (as a simplified example): nr.of.columns <- 4 myconstant <- 27.5 mymatrix <- matrix(numeric(0), nrow=5, ncol=nr.of.columns) mymatrix[,1] <- 1:5 for (i in 2:nr.of.columns) { mymatrix[,i] <- myconstant * mymatrix[,i-1] } Can anyone give me some advice whether it is possible to avoid this loop (and if yes: how)? Any suggestions are welcome! Thanks, Roland +++++ This mail has been sent through the MPI for Demographic Rese...{{dropped}} ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html +++++ This mail has been sent through the MPI for Demographic Rese...{{dropped}} ______________________________________________ [email protected] mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
