operators (version 0.2.0)

patternFilter: Regular expression filters

Description

Filters a character vector by a regular expression.

Usage

x %~|% rx
x %!~|% rx

Value

'%~|%' : a character vector containing all the elements of x

that match the regular expression rx or NULL if there is no match.

'%!~|%' : a character vector containing all the elements of

x that do not match the regular expression rx.

Arguments

x

text to manipulate

rx

regular expression

Examples

 cols <- colors()
 cols %~|% "^blue"

 ### blue colors that don't finish with a digit
 ( a1 <- cols %~|% "blue" %!~|% "\\\\d$"         )
 ( a2 <- cols %~|% "blue[^0-9]*$"                )
 ( a3 <- grep( "blue[^0-9]*", cols, value = TRUE ) )

 # using perl regular expressions

 ### not necessary since p is in the default of the package
 with( options( operators.regexpr = "p" ), {
 	( a4 <- grep( "blue[^\\\\d]*", cols, value = TRUE, perl = TRUE  ) )
 	( a5 <- cols %~|% "blue[^\\\\d]*$" )
 })

 ### blue colors that contain a r
 cols %~|% "blue" %~|% "r"
 grep( "r", grep( "blue", cols, value = TRUE ), value = TRUE  )

 ### blue colors that don't contain a r
 cols %~|% "blue" %!~|% "r"
 cols %~|% "^[^r]*blue[^r]*$"

 grep( "^[^r]*$", grep( "blue", cols, value = TRUE ), value = TRUE  ) # tricky and verbose
 # or in two steps, ... laborious
 bluecols <- grep( "blue", cols, value = TRUE )
 bluecols[ -grep( "r", bluecols) ]