1# Simply call 'first' or 'last' with a different default value for 'n'.
2first <- function(x, n=1, ...) head(x, n=n, ...)
3last  <- function(x, n=1, ...) tail(x, n=n, ...)
4
5"first<-" <- function(x, n=1, ..., value )
6{
7  x[1:n] <- value[1:n]
8  x
9}
10
11"last<-" <- function(x, n=1, ..., value )
12{
13  index <- seq( length(x)-n+1, length(x) )
14  x[index] <- value[1:n]
15  x
16}
17