like: Convenience function for calling grep.

In Rdatatable/data.table: Extension of `data.frame`

Convenience function for calling grep.

Description

Intended for use in i in [.data.table, i.e., for subsetting/filtering.

Syntax should be familiar to SQL users, with interpretation as regex.

Usage

like(vector, pattern, ignore.case = FALSE, fixed = FALSE, perl = FALSE)
vector %like% pattern
vector %ilike% pattern
vector %flike% pattern
vector %plike% pattern

Arguments

vector	Either a character or a factor vector.
pattern	Pattern to be matched
ignore.case	logical; is pattern case-sensitive?
fixed	logical; should pattern be interpreted as a literal string (i.e., ignoring regular expressions)?
perl	logical; is pattern Perl-compatible regular expression?

Details

Internally, like is essentially a wrapper around base::grepl, except that it is smarter about handling factor input (base::grep uses slow as.character conversion).

Value

Logical vector, TRUE for items that match pattern.

Note

Current implementation does not make use of sorted keys.

See Also

base::grepl

Examples

DT = data.table(Name=c("Mary","George","Martha"), Salary=c(2,3,4))
DT[Name %like% "^Mar"]
DT[Name %ilike% "mar"]
DT[Name %flike% "Mar"]
DT[Name %plike% "(?=Ma)(?=.*y)"]

Rdatatable/data.table documentation built on Dec. 28, 2024, 5:20 p.m.