R/search_count_bound.R

In stringi: Fast and Portable Character String Processing Facilities

# kate: default-dictionary en_US

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#' @title
#' Count the Number of Text Boundaries
#'
#' @description
#' These functions determine the number of text boundaries
#' (like character, word, line, or sentence boundaries) in a string.
#'
#' @details
#' Vectorized over \code{str}.
#'
#' For more information on text boundary analysis
#' performed by \pkg{ICU}'s \code{BreakIterator}, see
#' \link{stringi-search-boundaries}.
#'
#' In case of \code{stri_count_words},
#' just like in \code{\link{stri_extract_all_words}} and
#' \code{\link{stri_locate_all_words}},
#' \pkg{ICU}'s word \code{BreakIterator} iterator is used
#' to locate the word boundaries, and all non-word characters
#' (\code{UBRK_WORD_NONE} rule status) are ignored.
#' This function is equivalent to a call to
#' \code{\link{stri_count_boundaries}(str, type='word', skip_word_none=TRUE, locale=locale)}.
#'
#' Note that a \code{BreakIterator} of type \code{character}
#' may be used to count the number of \emph{Unicode characters} in a string.
#' The \code{\link{stri_length}} function,
#' which aims to count the number of \emph{Unicode code points},
#' might report different results.
#'
#' Moreover, a \code{BreakIterator} of type \code{sentence}
#' may be used to count the number of sentences in a text piece.
#'
#'
#' @param str character vector or an object coercible to
#' @param opts_brkiter a named list with \pkg{ICU} BreakIterator's settings,
#' see \code{\link{stri_opts_brkiter}};
#' \code{NULL} for the default break iterator, i.e., \code{line_break}
#' @param ... additional settings for \code{opts_brkiter}
#' @param locale \code{NULL} or \code{''} for text boundary analysis following
#' the conventions of the default locale, or a single string with
#' locale identifier, see \link{stringi-locale}
#'
#' @return
#' Both functions return an integer vector.
#'
#' @examples
#' test <- 'The\u00a0above-mentioned    features are very useful. Spam, spam, eggs, bacon, and spam.'
#' stri_count_boundaries(test, type='word')
#' stri_count_boundaries(test, type='sentence')
#' stri_count_boundaries(test, type='character')
#' stri_count_words(test)
#'
#' test2 <- stri_trans_nfkd('\u03c0\u0153\u0119\u00a9\u00df\u2190\u2193\u2192')
#' stri_count_boundaries(test2, type='character')
#' stri_length(test2)
#' stri_numbytes(test2)
#'
#' @export
#' @family search_count
#' @family locale_sensitive
#' @family text_boundaries
#' @rdname stri_count_boundaries
stri_count_boundaries <- function(str, ..., opts_brkiter = NULL)
{
    if (!missing(...))
        opts_brkiter <- do.call(stri_opts_brkiter, as.list(c(opts_brkiter, ...)))
    .Call(C_stri_count_boundaries, str, opts_brkiter)
}


#' @export
#' @rdname stri_count_boundaries
stri_count_words <- function(str, locale = NULL)
{
    stri_count_boundaries(str,
        opts_brkiter = stri_opts_brkiter(type = "word", skip_word_none = TRUE,
        locale = locale))
}