R: Convenience versions of grep

lgrep {Epi} | R Documentation

## 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

### See Also

`grep`

### 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 )

[Package Epi version 2.47 Index]