[Rd] Add first() and last() to utils?

[Gregory Warnes]

Hi all,

I've been using first() and last() for some time instead of x[1] and
x[length(x)] for vectors, and I gradually added methods for lists,
matrices, and data.frames.

In preparing the next release of the 'gdata' package (2.16.1) I settled on
these definitions, which harness the existing methods for head() and tail():

# Simply call 'first' or 'last' with a different default value for 'n'.
first <- function(x, n=1, ...) head(x, n=n, ...)
last  <- function(x, n=1, ...) tail(x, n=n, ...)


This works nicely, but Brian noted that packages 'data.table' and 'xts'
also provide functions/S3 methods for head() and/or tail().

Would it make sense to add these definitions to package 'utils' to make
them generally available?

-Greg

-- 
"Whereas true religion and good morals are the only solid foundations of
public liberty and happiness . . . it is hereby earnestly recommended to
the several States to take the most effectual measures for the
encouragement thereof." Continental Congress, 1778

	[[alternative HTML version deleted]]