head
Returns the first or last parts of a vector, matrix, table, data frame
or function. Since head() and tail() are generic
functions, they may also have been extended to other classes.
- Keywords
- manip
Usage
head(x, …)
# S3 method for default
head(x, n = 6L, …)
# S3 method for data.frame
head(x, n = 6L, …)
# S3 method for matrix
head(x, n = 6L, …)
# S3 method for ftable
head(x, n = 6L, …)
# S3 method for table
head(x, n = 6L, …)
# S3 method for function
head(x, n = 6L, …)tail(x, …)
# S3 method for default
tail(x, n = 6L, …)
# S3 method for data.frame
tail(x, n = 6L, …)
# S3 method for matrix
tail(x, n = 6L, addrownums = TRUE, …)
# S3 method for ftable
tail(x, n = 6L, addrownums = FALSE, …)
# S3 method for table
tail(x, n = 6L, addrownums = TRUE, …)
# S3 method for function
tail(x, n = 6L, …)
Arguments
- x
- an object
- 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
nlast/first number of elements ofx. - addrownums
- if there are no row names, create them from the row numbers.
- …
- arguments to be passed to or from other methods.
Details
For matrices, 2-dim tables and data frames, head() (tail()) returns
the first (last) n rows when n > 0 or all but the
last (first) n rows when n < 0. head.matrix() and
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 tail() will add row names of
the form "[n,]" to the result, so that it looks similar to the
last lines of x when printed. Setting addrownums =
FALSE suppresses this behaviour.
Value
An object (usually) like x but generally smaller. For
ftable objects x, a transformed format(x).
Examples
library(utils)
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))