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Problem with mutli-dimensional array

6 messages · Berend Hasselman, Rui Barradas, Loukia Spineli

Berend Hasselman
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On 02-10-2012, at 16:20, Loukia Spineli <spineliloukia26 at gmail.com> wrote:

            

      
      
      
    

        
If you had inserted this line

            cat("i=",i,"l=",l,"j=",j,"k=",k,"\n")

before the assignment to results[,,l,i] in the inner loop you could have quite easily seen what the problem is.
The counter l (letter el) keeps on increasing in your code and when it reaches 65 R will complain.

So at an appropriate place in the code you need to reset l to 1.
I suggest you move the assignment l<-1 to just before the  line with for( j in 1:Nx[i]) ...
Whether the results are what you desire is up to you to decide.

Please use some more whitespace  and do some indenting in your code. As presented it is unreadable.

Berend

  
  


  


      

    

    

      
      

        


  

        

      Rui Barradas
    

    

      
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Hello,
See if this is it.


Nx <- rep(0,length(x))
Ny <- rep(0,length(y))
n <- (x+1)*(y+1)
results <- array(0, dim=c(2,2,64,7))
# l <- 1 # <--------------------------- This changed place
for(i in 1:length(x)){
     Nx[i] <- length(1:(x[i]+1))
     Ny[i] <- length(1:(y[i]+1))
     l <- 1 # <----------------------- To here
     for(j in 1:(Nx[i])){
         for(k in 1:(Ny[i])){


Hope this helps,

Rui Barradas
Em 02-10-2012 15:20, Loukia Spineli escreveu:

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        
      

    

    

      
      

        


  

        

      Rui Barradas
    

    

      
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Hello,

I'm glad it helped.
Now you have what is a data structure problem. The computations are the 
same but in a different output.

First of all a terminology issue. In R the correct names for the data 
structures you've refered to are 'list', 'matrix' and 'array'. To make 
it short,

vector ---> 1-dim
matrix ---> 2-dim
array ---> n-dim

and

list ---> no dim attribute, can hold any type of data structure.

Your first sentence of this last post would read (changes in uppercase)

Actually I am trying to make an LIST of length 7, where each LIST ELEMENT
  IS AN ARRAY containing a different number of 2 by 2 matrices.

In what follows, for the 3-dim array case I'll use the naming convention 
[row, column, slice].
Each of your output list elements is an array with a possibly varying 
number of slices. Right now all of them have 64 slices.

1. You need a list of 7 elements, each of them indexed by your current 'i';
2. Each of those elements is a 3-dim array, each slice is a 2x2 matrix 
and each slice is indexed by your current 'l'.
3. Let's try it.


Nx <- rep(0, length(x))
Ny <- rep(0, length(y))
n <- (x+1)*(y+1)

results <- vector("list", 7)

for(i in 1:length(x)){
     Nx[i] <- length(1:(x[i]+1))
     Ny[i] <- length(1:(y[i]+1))
     results[[i]] <- array(dim = c(2, 2, n[i]))
     l <- 1
     for(j in 1:(Nx[i])){
         for(k in 1:(Ny[i])){
             tmp <- c((0:x[i])[j], (0:y[i])[k],-(0:x[i])[j], -(0:y[i])[k])
             results[[i]][,, l] <- mat.stat[,,i] + matrix(tmp, nrow=2, 
ncol=2,byrow=T)
             l <- l + 1
         }
     }
}
results


I think this is it. Let us now if not.

Rui Barradas
Em 03-10-2012 08:48, Loukia Spineli escreveu: