dim(x) dim(x) <- values
dim and dim<- are generic.
For an array (and hence in particular, for a matrix) they retrieve or
set the dim attribute of the object.
dim has a method for data frames, which returns the length of
the row.names attribute of x and the length of x
(the numbers of ``rows'' and ``columns'').
ncol, nrow and dimnames.x <- 1:12 ; dim(x) <- c(3,4) x # simple versions of nrow and ncol could be defined as follows nrow0 <- function(x) dim(x)[1] ncol0 <- function(x) dim(x)[2]