R: Locate Specific Text Boundaries

stri_locate_all_boundaries {stringi} | R Documentation

## Locate Specific Text Boundaries

### Description

These functions locate specific text boundaries (like character, word, line, or sentence boundaries). `stri_locate_all_*` locate all the matches. On the other hand, `stri_locate_first_*` and `stri_locate_last_*` give the first or the last matches, respectively.

### Usage

    stri_locate_all_boundaries(str, omit_no_match = FALSE, ...,
      opts_brkiter = NULL)

    stri_locate_last_boundaries(str, ..., opts_brkiter = NULL)

    stri_locate_first_boundaries(str, ..., opts_brkiter = NULL)

    stri_locate_all_words(str, omit_no_match = FALSE, locale = NULL)

    stri_locate_last_words(str, locale = NULL)

    stri_locate_first_words(str, locale = NULL)

### Arguments

`str` | character vector or an object coercible to
`omit_no_match` | single logical value; if `FALSE`, then 2 missing values will indicate that there are no text boundaries
`...` | additional settings for `opts_brkiter`
`opts_brkiter` | a named list with ICU BreakIterator's settings as generated with `stri_opts_brkiter`; `NULL` for default break iterator, i.e. `line_break`
`locale` | `NULL` or `""` for text boundary analysis following the conventions of the default locale, or a single string with locale identifier, see stringi-locale

### Details

Vectorized over `str`.

For more information on the text boundary analysis performed by ICU's `BreakIterator`, see stringi-search-boundaries.

In case of `stri_locate_*_words`, just like in `stri_extract_all_words` and `stri_count_words`, ICU's word `BreakIterator` iterator is used to locate word boundaries, and all non-word characters (`UBRK_WORD_NONE` rule status) are ignored. This is function is equivalent to a call to `stri_locate_*_boundaries(str, type="word", skip_word_none=TRUE, locale=locale)`

### Value

For `stri_locate_all_*`, a list of `length(str)` integer matrices is returned. The first column gives the start positions of substrings between located boundaries, and the second column gives the end positions. The indices are code point-based, thus they may be passed e.g. to the `stri_sub` function. Moreover, you may get two `NA`s in one row for no match (if `omit_no_match` is `FALSE`) or `NA` arguments.

`stri_locate_first_*` and `stri_locate_last_*`, on the other hand, return an integer matrix with two columns, giving the start and end positions of the first or the last matches, respectively, and two `NA`s if and only if they are not found.

### See Also

Other search_locate: `stri_locate_all`, `stringi-search`

Other indexing: `stri_locate_all`, `stri_sub`

Other locale_sensitive: `%s<%`, `stri_compare`, `stri_count_boundaries`, `stri_duplicated`, `stri_enc_detect2`, `stri_extract_all_boundaries`, `stri_opts_collator`, `stri_order`, `stri_split_boundaries`, `stri_trans_tolower`, `stri_unique`, `stri_wrap`, `stringi-locale`, `stringi-search-boundaries`, `stringi-search-coll`

Other text_boundaries: `stri_count_boundaries`, `stri_extract_all_boundaries`, `stri_opts_brkiter`, `stri_split_boundaries`, `stri_split_lines`, `stri_trans_tolower`, `stri_wrap`, `stringi-search-boundaries`, `stringi-search`

### Examples

    test <- "The\u00a0above-mentioned    features are very useful. Warm thanks to their developers."
    stri_locate_all_boundaries(test, type="line")
    stri_locate_all_boundaries(test, type="word")
    stri_locate_all_boundaries(test, type="sentence")
    stri_locate_all_boundaries(test, type="character")
    stri_locate_all_words(test)

    stri_extract_all_boundaries("Mr. Jones and Mrs. Brown are very happy.
    So am I, Prof. Smith.", type="sentence", locale="en_US@ss=standard") # ICU >= 56 only

[Package stringi version 1.2.4 Index]