Create an Expanding Matrix in R -

os: linux centos 6.5 / centos 7
machine: "special" 2.5 terabytes of physical memory (yes, really)
programming language: r

problem: in r, practice (appears be) allocate before loop matrix big final result. in case, final matrix size undetermined @ initiation.

thus, cleanest way of creating expanding matrix in r?

a key point wanted avoid overhead of memory copy @ point of expansion. if way, ok not preferred

important: familiar kernel level programming, kernel level memory management, page handling systems, etc. i new r, , learning r. (it interesting, , useful) in instance, trying create scenario demonstrate memory expansion of matrix without pre-allocation of memory, or fall allocation of size n matrix extensions (incremental expansion using memory chunks).

problem example

ok, in described scenario might create matrix a, create expanded matrix b, copy b perform operation on larger matrix.

an alternate approach expand a, populate result , iterate...

for example, might start using outer(), "outer()" creates new matrix @ each invocation. looking expand existing matrix...

x<- outer(1:2,1:2,"*") x      [,1] [,2] [1,]    1    2   [2,]    2    4   

...

x<-outer(1:3,1:3,"*") x       [,1] [,2] [,3] [1,]    1    2    3 [2,]    2    4    6 [3,]    3    6    9 

...

x<-outer(1:3,1:3,"*") x       [,1] [,2] [,3] [,4] [1,]    1    2    3    4 [2,]    2    4    6    8 [3,]    3    6    9   12 [4,]    4    8   12   16 

hence, question:

"what preferred way create dynamically allocated matrix in r, without pre-allocation of large matrix?"

thanks in advance pointers , reading recommendations. appreciated.

in general, should allocate before loop matrix big final result , then, in each iteration, fill values. in example (if understood correctly how values filled), can try:

 #set dimension of final matrix  n<-10  #create matrix  res<-matrix(ncol=n,nrow=n)  #fill values  res[1,1]<-1  (i in 2:n) {    tmp<-c(i,(i+2):(2*i))    res[i,1:i]<-tmp    res[1:i,i]<-tmp    print(res)  }