[R] Embedding lists in matrices and matrices in lists

[Michael Kogan]

This works, but then I can only save a single matrix in each 
database[x,y] while I need to save a list of matrices.

Gabor Grothendieck schrieb:
> Try this:
>
>   
>> database[[4,4]] <- tetrahedron
>> database[[4,4]][1,]
>>     
> [1] 0 1 1 1
>
>
> On Wed, Aug 19, 2009 at 6:02 AM, Michael Kogan<michael.kogan at gmx.net> wrote:
>   
>> Unfortunately the  matrix(list(),x,y) way seems to have some limitations. I
>> want to continue working with the matrices which are saved in the database
>> matrix. But for example the following doesn't work:
>>
>> tetrahedron=matrix(c(
>> 0,1,1,1,
>> 1,0,1,1,
>> 1,1,0,1,
>> 1,1,1,0
>> ),nrow=4, byrow=TRUE) # an example matrix
>>
>> database=matrix(list(),5,5) # create database matrix
>> database[[4,4]]=list(tetrahedron) # save example matrix in database matrix
>>
>> ## try to access the first row of the saved example matrix ##
>> database[[4,4]][1] # prints the whole example matrix
>> database[[4,4]][1][1,] # should have printed the first row of the example
>> matrix, but gives:
>>
>> Error in database[[4, 4]][1][1,] : incorrect number of dimensions
>> Execution halted
>>
>> The same happens with database[[4,4]][1,]... Is there any way to access the
>> saved matrices like "normal" ones?
>>
>> Thanks,
>> Michael
>>
>>
>>     
>
>