keep_pos {mclm}

Subset an object by index

Description

These methods can be used to subset objects based on a numeric vector of indices.

Usage

keep_pos(x, pos, invert = FALSE, ...)

## S3 method for class 'fnames'
drop_pos(x, pos, ...)

## S3 method for class 'fnames'
keep_pos(x, pos, invert = FALSE, ...)

## S3 method for class 'freqlist'
drop_pos(x, pos, ...)

## S3 method for class 'freqlist'
keep_pos(x, pos, invert = FALSE, ...)

drop_pos(x, pos, ...)

## S3 method for class 'tokens'
drop_pos(x, pos, ...)

## S3 method for class 'tokens'
keep_pos(x, pos, invert = FALSE, ...)

## S3 method for class 'types'
drop_pos(x, pos, ...)

## S3 method for class 'types'
keep_pos(x, pos, invert = FALSE, ...)

Arguments

x

An object of any of the classes for which the method is implemented.

pos

A numeric vector, the numbers in which identify positions (= indices) of items in x.

If the numbers are positive, then their values point to the items that are to be selected.

If the numbers are negative, then their absolute values point to the items that are not to be selected. Positive and negative numbers must not be mixed.

invert

Logical. Whether the matches should be selected rather than the non-matches.

...

Additional arguments.

Details

The methods keep_pos() and drop_pos() are part of a family of methods of the mclm package used to subset different objects. The methods starting with keep_ extract the items in x based on the criterion specified by the second argument. In contrast, the methods starting with drop_ exclude the items that match the criterion in the same argument.

Calling a drop_ method is equivalent to calling its keep_ counterpart when the invert argument is TRUE.

Value

Object of the same class as x with the selected elements only.

See Also

Other subsetters: brackets, keep_bool(), keep_re(), keep_types()

Examples

# For a 'freqlist' object --------------------
(flist <- freqlist("The man and the mouse.", as_text = TRUE))

keep_pos(flist, c(2, 3))

# For a 'types' object -----------------------
(tps <- as_types(letters[1:10]))

keep_pos(tps, c(1, 3, 5, 7, 9))
drop_pos(tps, c(1, 3, 5, 7, 9))

# For a 'tokens' object ----------------------
(tks <- as_tokens(letters[1:10]))

keep_pos(tks, c(1, 3, 5, 7, 9))
drop_pos(tks, c(1, 3, 5, 7, 9))