[R] evaluating string variables

From: Leonardo Sepulveda Durán <leonardosepulveda_at_gmail.com>
Date: Sat 13 Aug 2005 - 00:44:25 EST


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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