R/subset.R

In re2r: RE2 Regular Expression

## This file is part of the 're2r' package for R.
## Copyright (C) 2016, Qin Wenfeng
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#' Keep strings matching a pattern.
#'
#' This is a convenient wrapper around \code{x[re2_detect(x, pattern)]}. Vectorised over strings and patterns.
#'
#' @inheritParams re2_detect
#' @param omit_na omit na result
#' @return A character vector.
#' @export
#' @examples
#' fruit <- c("apple", "banana", "pear", "pinapple")
#' re2_subset(fruit, "a")
#' re2_subset(fruit, "^a")
#' re2_subset(fruit, "a$")
#' re2_subset(fruit, "b")
#' re2_subset(fruit, "[aeiou]")
#'
#' re2_subset(c("a", NA, "b"), ".")
re2_subset <-
    function(string,
             pattern,
             anchor = 0,
             omit_na = TRUE,
             parallel = FALSE,
             grain_size = 100000,
             ...) {
        if (is.character(pattern) || mode(pattern) == "logical") {
            pattern = re2(pattern, ...)
        }
        cpp_subset(stri_enc_toutf8(string), pattern , anchor, parallel, grain_size, omit_na)
    }