% File src/library/utils/man/head.Rd % Part of the R package, http://www.R-project.org % Copyright 1995-2007 R Core Team % Distributed under GPL 2 or later \name{head} \alias{head} \alias{head.default} \alias{head.data.frame} \alias{head.function} \alias{head.ftable} \alias{head.table} \alias{head.matrix} \alias{tail} \alias{tail.default} \alias{tail.data.frame} \alias{tail.function} \alias{tail.ftable} \alias{tail.table} \alias{tail.matrix} \title{ Return the First or Last Part of an Object } \description{ Returns the first or last parts of a vector, matrix, table, data frame or function. Since \code{head()} and \code{tail()} are generic functions, they may also have been extended to other classes. } \usage{ head(x, \dots) \method{head}{default}(x, n = 6L, \dots) \method{head}{data.frame}(x, n = 6L, \dots) \method{head}{matrix}(x, n = 6L, \dots) \method{head}{ftable}(x, n = 6L, \dots) \method{head}{table}(x, n = 6L, \dots) \method{head}{function}(x, n = 6L, \dots) tail(x, \dots) \method{tail}{default}(x, n = 6L, \dots) \method{tail}{data.frame}(x, n = 6L, \dots) \method{tail}{matrix}(x, n = 6L, addrownums = TRUE, \dots) \method{tail}{ftable}(x, n = 6L, addrownums = FALSE, \dots) \method{tail}{table}(x, n = 6L, addrownums = TRUE, \dots) \method{tail}{function}(x, n = 6L, \dots) } \arguments{ \item{x}{an object} \item{n}{a single integer. If positive, size for the resulting object: number of elements for a vector (including lists), rows for a matrix or data frame or lines for a function. If negative, all but the \code{n} last/first number of elements of \code{x}.} \item{addrownums}{if there are no row names, create them from the row numbers.} \item{\dots}{arguments to be passed to or from other methods.} } \details{ For matrices, 2-dim tables and data frames, \code{head()} (\code{tail()}) returns the first (last) \code{n} rows when \code{n > 0} or all but the last (first) \code{n} rows when \code{n < 0}. \code{head.matrix()} and \code{tail.matrix()} are exported. For functions, the lines of the deparsed function are returned as character strings. If a matrix has no row names, then \code{tail()} will add row names of the form \code{"[n,]"} to the result, so that it looks similar to the last lines of \code{x} when printed. Setting \code{addrownums = FALSE} suppresses this behaviour. } \value{ An object (usually) like \code{x} but generally smaller. For \code{\link{ftable}} objects \code{x}, a transformed \code{format(x)}. } \author{ Patrick Burns, improved and corrected by R-Core. Negative argument added by Vincent Goulet. } \examples{ head(letters) head(letters, n = -6L) head(freeny.x, n = 10L) head(freeny.y) tail(letters) tail(letters, n = -6L) tail(freeny.x) tail(freeny.y) tail(library) head(stats::ftable(Titanic)) } \keyword{ manip }