On 11/08/11 13:11, David Winsemius wrote:
On Aug 10, 2011, at 8:23 PM, Andra Isan wrote:
Hi All,
I would like to create a matrix in R but I dont know the size of my
matrix. I only know the size of the columns but not the size of the
rows. So, is there any way to create a dynamic matrix of size NULL by
n_cols? and then add to that matrix?
I know for a vector, I can do this: x= NULL but is there any way to
do the same for a matrix as well?
No. You cannot make an R matrix without knowing the number of rows. By
definition an R matix has two integer dimensions. Alternatives: You
can rbind to an existing matrix, or you can make a larger than
necessary matrix filled with NA's and then fill and later extract a
subset of the rows.
Wrong-oh, David. :-) Check this out:
> m <- matrix(0,nrow=0,ncol=5)
> m
[,1] [,2] [,3] [,4] [,5]
cheers,
Rolf
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