R: Return the First or Last Part of an Object

head {spam} | R Documentation

## Return the First or Last Part of an Object

### Description

Returns the upper left or lower right part of a `spam` object.

### Usage

    ## S4 method for signature 'spam'
    head(x, n = 6L, m = n, ...)
    ## S4 method for signature 'spam'
    tail(x, n = 6L, m = n, addrownums = TRUE, ...)

### Arguments

`x` | a `spam` 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 `n` last/first number of elements of `x`.
`m` | similar to `n` but for the number of columns.
`addrownums` | create row and column namves them from the selected elements.
`...` | 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 and `m` columns when `n > 0` or all but the last (first) `n` rows when `n < 0` (with similar behavior for `m`).

`tail()` will add row and column names of the form `"[n,]"` and `"[,n]"` to the result, so that it looks similar to the last lines and columns of `x` when printed. Setting `addrownums = FALSE` suppresses this behaviour.

A method for `spam.chol.NgPeyton` objects is exported as well.

### Value

An regular matrix.

### Author(s)

Reinhard Furrer

### Examples

    head( precmat.RW2( 10))
    tail( precmat.season(n=10, season=3), n=4, m=10)

[Package spam version 2.2-2 Index]