[R] Embedding lists in matrices and matrices in lists

[jim holtman]

Is this what you want:

> x <- matrix(list(),3,3)  # create a matrix of lists
> # create matrices for testing
> for(i in 1:3){
+     for (j in 1:3){
+         x[[i,j]] <- matrix(runif((i+1) * (j+1)), i+1)
+     }
+ }
>
>
> x
     [,1]      [,2]       [,3]
[1,] Numeric,4 Numeric,6  Numeric,8
[2,] Numeric,6 Numeric,9  Numeric,12
[3,] Numeric,8 Numeric,12 Numeric,16
> x[[2,2]]  # extract one of them
           [,1]      [,2]      [,3]
[1,] 0.26722067 0.3823880 0.4820801
[2,] 0.38611409 0.8696908 0.5995658
[3,] 0.01339033 0.3403490 0.4935413
> str(x)  # structure of the data
List of 9
 $ : num [1:2, 1:2] 0.266 0.372 0.573 0.908
 $ : num [1:3, 1:2] 0.38 0.777 0.935 0.212 0.652 ...
 $ : num [1:4, 1:2] 0.7894 0.0233 0.4772 0.7323 0.6927 ...
 $ : num [1:2, 1:3] 0.202 0.898 0.945 0.661 0.629 ...
 $ : num [1:3, 1:3] 0.2672 0.3861 0.0134 0.3824 0.8697 ...
 $ : num [1:4, 1:3] 0.2448 0.0707 0.0995 0.3163 0.5186 ...
 $ : num [1:2, 1:4] 0.206 0.177 0.687 0.384 0.77 ...
 $ : num [1:3, 1:4] 0.186 0.827 0.668 0.794 0.108 ...
 $ : num [1:4, 1:4] 0.258 0.4785 0.7663 0.0842 0.8753 ...
 - attr(*, "dim")= int [1:2] 3 3
>


On Tue, Aug 18, 2009 at 4:48 AM, Michael Kogan<michael.kogan at gmx.net> wrote:
> Hi,
>
> I'm new to programming, new to R and even new to mailing lists so please be
> patient with me. I need to manage many matrices generated by an R program.
> These matrices have different dimensions and I'd like to group them somehow.
> The best way would be to have a big matrix (let's call it database) where
> every element database[x,y] consists of a list of matrices that all have the
> dimensions ncol(matrix1)=x and nrow(matrix1)=y. So those matrices have to be
> embedded into lists and the lists have to be embedded in the big database
> matrix. If I simply try
>
>   database=matrix(0,10,10)
>   database[4,4]=c(matrix1,matrix2)
>
> I get
>
>   Error in database[4, 4] = c(matrix1, matrix2) :
>     number of items to replace is not a multiple of replacement length
>   Execution halted
>
> which makes sense of course... Is there any possibility to make this work?
> Or maybe there is a better way to organize those matrices?
>
> Regards,
> Michael
>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?