Epi: lgrep – R documentation

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lgrep

Convenience versions of grep

Description

Often you want the elements of a vector (or its names or levels) that meet a certain pattern. But grep only gives you the position, so these functions are designed to give you that.

Usage

fgrep( pattern, x, ... )
ngrep( pattern, x, ... )
lgrep( pattern, x, ... )

Arguments

`pattern`	Pattern searched for.
`x`	Object where `pattern` is searched. Or in whose `names` or `levels` attributes `pattern` is sought.
`...`	Arguments passed on to `grep`.

Value

Elements of the input x (fgrep) or its names attribute (ngrep) or levels attribute (lgrep).

Author(s)

Bendix Carstensen, b@bxc.dk, http://bendixcarstensen.com

Examples

ff <- factor( ll <- paste( sample( letters[1:3], 20, replace=TRUE ),
                           sample( letters[1:3], 20, replace=TRUE ), sep="" ) )
ff
fgrep( "a", ff )
fgrep( "a", ll )
ngrep( "a", ff )
lgrep( "a", ff )
lgrep( "a", ff, invert=TRUE )

Epi

Statistical Analysis in Epidemiology

v2.44

GPL-2

Authors

Bendix Carstensen [aut, cre], Martyn Plummer [aut], Esa Laara [ctb], Michael Hills [ctb]

Initial release

2021-02-28