| head_tail {photobiology} | R Documentation |
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.
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, ...)
x |
an R object. |
n |
a single integer. If positive, half the 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, to be retained from each end. If negative, all but the n last and n first number of elements of x. |
... |
arguments to be passed to or from other methods. |
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.
An object (usually) like x but generally smaller. For ftable objects
x, a transformed format(x).
default: Default method
data.frame: Specialization for data.frame objects
matrix: Specialization for matrix
function: Specialization for function
table: Specialization for table
ftable: Specialization for ftable
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'. I have been missing this method especially when checking spectral data, as both ends are of interest.
head_tail() methods for function, table and ftable classes, are
wrappers for head() method.
head, and compare the examples and the values
returned to the examples below.
head_tail(letters) head_tail(letters, n = -6L) head_tail(freeny.x, n = 10L) head_tail(freeny.y) head_tail(stats::ftable(Titanic))