head_tail {photobiology}

Return the First and Last Parts of an Object

Description

Returns the first and last "parts" (rows or members) of a spectrum, dataframe, vector, function, table or ftable. In other words, the combined output from methods head and tail.

Usage

head_tail(x, n, ...)

## Default S3 method:
head_tail(x, n = 3L, ...)

## S3 method for class 'data.frame'
head_tail(x, n = 3L, ...)

## S3 method for class 'matrix'
head_tail(x, n = 3L, ...)

## S3 method for class ''function''
head_tail(x, n = 6L, ...)

## S3 method for class 'table'
head_tail(x, n = 6L, ...)

## S3 method for class 'ftable'
head_tail(x, n = 6L, ...)

Arguments

x

an R object.

n

integer. If positive, n rows or members in the returned object are copied from each of "head" and "tail" of x. If negative, all except n elements of x from each of "head" and "tail" are returned.

...

arguments to be passed to or from other methods.

Details

The value returned by head_tail() is equivalent to row binding the the values returned by head() and tail(), although not implemented in this way. The same specializations as defined in package 'utils' for head() and tail() have been implemented.

Value

An object (usually) like x but smaller, except when n = 0. For ftable objects x, a transformed format(x).

Methods (by class)

• head_tail(default):

• head_tail(data.frame):

• head_tail(matrix):

• head_tail(`function`):

• head_tail(table):

• head_tail(ftable):

Note

For some types of input, like functions, the output may be confusing, however, we have opted for consistency with existing functions. The code is in part a revision of that of head() and tail() from package ‘utils’. This method is especially useful when checking spectral data, as both ends are of interest.

head_tail() methods for function, table and ftable classes, are wrappers for head() method.

See Also

head, and compare the examples and the values returned to the examples below.

Examples

head_tail(letters)
head_tail(letters, n = -6L)
head_tail(freeny.x, n = 10L)
head_tail(freeny.y)

head_tail(stats::ftable(Titanic))