[R] Avoiding a Loop?

[Uwe Ligges]

Rau, Roland wrote:

> 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]
> }

   nr.of.columns <- 4
   myconstant <- 27.5
   mycolumn <- 1:5
   outer(mycolumn, myconstant^(0:(nr.of.columns-1)))

Uwe Ligges



> 
> 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}}
> 
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html