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