R/count.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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#' Count the number of matches in a string.
#'
#' Count the number of matches in a string. Vectorised over strings and patterns.
#' @param pattern a character vector or pre-compiled regular expressions
#' @param string a character vector
#' @param anchor see \code{\link{UNANCHORED}}
#' @param parallel use multithread
#' @param grain_size a minimum chunk size for tuning the behavior of parallel algorithms
#' @param ... further arguments passed to \code{\link{re2}}
#' @return An integer vector.
#' @examples
#' re2_count("one", "(o.e)")
#' re2_count("123-234-2222", "\\d\\d\\d-\\d\\d\\d-\\d\\d\\d\\d")
#'
#' words = c("sunny","beach","happy","really")
#' re2_count(words, "y")
#' re2_count(words, "^b")
#' re2_count(words, "[abc]")
#'
#' # vectorize
#' re2_count("This", letters)
#' @export
re2_count = function(string,
                      pattern,
                      anchor = UNANCHORED,
                      parallel = FALSE,
                      grain_size = 100000,
                      ...) {
    if (is.character(pattern) || mode(pattern) == "logical") {
        pattern = re2(pattern, ...)
    }
    cpp_count(stri_enc_toutf8(string),
              regexp = pattern,
              anchor = anchor,
              parallel = parallel,
              grain_size = grain_size)
}