R help - Aug 2009 - Embedding lists in matrices and matrices in lists

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

Try this:
> m12 <- matrix(10, 1, 2)
> m22 <- matrix(20, 2, 2)
> # create matrix of lists of matrices
> M <- matrix(list(list(1, 2), list(m12, m12), list(t(m12)), list(m22,
m22, m22)), 2, 2)
> M
     [,1]   [,2]
[1,] List,2 List,1
[2,] List,2 List,3
> M[[1,2]]
[[1]]
     [,1]
[1,]   10
[2,]   10
> M[[2,1]]
[[1]]
     [,1] [,2]
[1,]   10   10

[[2]]
     [,1] [,2]
[1,]   10   10


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
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

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
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


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

What is the problem that you are trying to solve?