[R] Error in rep.int() invalid 'times' value

[Maram SAlem]

Dear All,

I'm trying to do a simple task (which is in fact a tiny part of a larger
code).

I want to create a matrix, D, each of its columns is a sequence from 0 to
(n-m), by 1. Then, using D, I want to create another matrix ED, whose rows
represent all the possible combinations of the elements of the columns of
D. Then from ED, I'll select only the rows whose sum is less than or equal
to (n-m), which will be called the matrix s. I used the following code:

> n=5
> m=3
> D<-matrix(0,nrow=n-m+1,ncol=m-1)
> for (i in 1:m-1)
+  {
+ D[,i]<-seq(0,n-m,1)
+  }
> ED <- do.call(`expand.grid`,as.data.frame(D))
> ED<-as.matrix(ED)

> lk<-which(rowSums(ED)<=(n-m))

> s<-ED[lk,]


This works perfectly well. But for rather larger values of n and m (which
are not so large actually), the number of all possible combinations of the
columns of D gets extremely large giving me this error (for n=25, m=15):

> ED <- do.call(`expand.grid`,as.data.frame(D))
Error in rep.int(rep.int(seq_len(nx), rep.int(rep.fac, nx)), orep) :
  invalid 'times' value
In addition: Warning message:
In rep.int(rep.int(seq_len(nx), rep.int(rep.fac, nx)), orep) :
  NAs introduced by coercion to integer range


Any help or suggestions will be greatly appreciated.

Thanks,

Maram Salem

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