[R] evaluating string variables

[Sean O'Riordain]

use paste() to construct the file name 
e.g. fn <- paste(i,".mat",sep="")

Sean

On 12/08/05, Leonardo Sepulveda Durán <leonardosepulveda at gmail.com> wrote:
> Hello!!!
> 
> I have a folder (C:/R/) with matrix files, named by number, i.e.
> 0.mat, 1.mat,...,1250.mat. In this case, they are 5x5 simetric
> matrices. I would like to compute a property for each matrix and put
> calculated values into a data frame for posterior ploting and
> printing. Below there is an example for 7 matrices (0.mat..6.mat)
> 
> #define data frame
> L <- data.frame(frame=numeric(7), L=numeric(7))
> f0<-1/(5*(5-1)) # first variable for computation
> 
> #loop over matrices, Open it , calculate property and put into data frame
> for(i in 0:6){
>         m<-matrix(scan('C:/R/i.mat', n=5*5),5,5, byrow=TRUE) # load matrix
>         f1<-geodist(m)
>         f2<-sum(colSums(f1$gdist))
>         l <-f0*f2
>        # Calculate property
>         L[i+1, ]<-c(i,l)
>       # Fill data frame
> }
> 
> but the matrix cannot be loaded, because it try to open a file named
> "i.mat". I don`t know how to loop with a counter named 'i', and use it
> to define the name of the file too. How can i do it? I have not found
> the way.
> 
> Leonardo
> 
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