[R] evaluating string variables

[Dimitris Rizopoulos]

look at ?paste(), e.g.,

paste("C:/R/", i, "mat", sep = "")

I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/16/336899
Fax: +32/16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Leonardo Sepulveda Durán" <leonardosepulveda at gmail.com>
To: <r-help at stat.math.ethz.ch>
Sent: Friday, August 12, 2005 4:44 PM
Subject: [R] evaluating string variables


> 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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