R/grep.R

In twolodzko/twextras: twextras

#' Search strings for multiple patterns
#' 
#' @param patterns    character string containing a regular expression
#'                    (or character string)
#' @param x           character vector
#' @param ignore.case if \code{FALSE}, the pattern matching is case
#'                    sensitive and if \code{TRUE}, case is ignored
#'                    during matching
#' @param perl        logical. Should perl-compatible regexps be used?
#' @param value       if \code{FALSE}, a vector containing the (integer)
#'                    indices of the matches determined by grep is
#'                    returned, and if \code{TRUE}, a vector containing
#'                    the matching elements themselves is returned
#' @param fixed       logical. If \code{TRUE}, pattern is a string to
#'                    be matched as is. Overrides all conflicting arguments
#' @param useBytes    logical. If \code{TRUE} the matching is done byte-by-byte
#'                    rather than character-by-character.
#' @param invert      logical. If \code{TRUE} return indices or values for elements
#'                    that do not match.
#' @param list        if \code{TRUE} list all matches
#' @param action      function for aggregating matches, e.g. \code{all}, \code{any},
#'                    \code{sum} (count maches), \code{mean} (proportion of matching)
#' 
#' @seealso \code{\link{grep}}
#' @export

mgrep <- function(patterns, x, ignore.case = FALSE, perl = FALSE, value = FALSE,
                  fixed = FALSE, useBytes = FALSE, invert = FALSE, list = FALSE) {
  out <- lapply(patterns, function(p) grep(p, x, ignore.case = ignore.case,
                                           perl = perl, value = value, fixed = fixed,
                                           useBytes = useBytes, invert = invert))
  if (list) {
    names(out) <- patterns
    out
  } else {
    unlist(out)
  }
}


#' @rdname mgrep
#' @export

mgrepl <- function(patterns, x, ignore.case = FALSE, perl = FALSE, fixed = FALSE,
                   useBytes = FALSE, action = "list") {
  out <- lapply(patterns, function(p) grepl(p, x, ignore.case = ignore.case,
                                            perl = perl, fixed = fixed,
                                            useBytes = useBytes))
  names(out) <- patterns
  if (action == "list") {
    out
  } else {
    apply(as.data.frame(out), 1, action)
  }
}