Extract Occurrences of a Pattern

These functions extract all substrings matching a given pattern. stri_extract_all_* extracts all the matches. On the other hand, stri_extract_first_* and stri_extract_last_* provide the first or the last matches, respectively.

stri_extract_all(str, ..., regex, fixed, coll, charclass)

stri_extract_first(str, ..., regex, fixed, coll, charclass)

stri_extract_last(str, ..., regex, fixed, coll, charclass)

stri_extract(str, ..., regex, fixed, coll, charclass, mode = c("first", "all", "last"))

stri_extract_all_charclass(str, pattern, merge = TRUE, simplify = FALSE, omit_no_match = FALSE)

stri_extract_first_charclass(str, pattern)

stri_extract_last_charclass(str, pattern)

stri_extract_all_coll(str, pattern, simplify = FALSE, omit_no_match = FALSE, ..., opts_collator = NULL)

stri_extract_first_coll(str, pattern, ..., opts_collator = NULL)

stri_extract_last_coll(str, pattern, ..., opts_collator = NULL)

stri_extract_all_regex(str, pattern, simplify = FALSE, omit_no_match = FALSE, ..., opts_regex = NULL)

stri_extract_first_regex(str, pattern, ..., opts_regex = NULL)

stri_extract_last_regex(str, pattern, ..., opts_regex = NULL)

stri_extract_all_fixed(str, pattern, simplify = FALSE, omit_no_match = FALSE, ..., opts_fixed = NULL)

stri_extract_first_fixed(str, pattern, ..., opts_fixed = NULL)

stri_extract_last_fixed(str, pattern, ..., opts_fixed = NULL)

character vector with strings to search in
supplementary arguments passed to the underlying functions, including additional settings for opts_collator, opts_regex, and so on
single string; one of: "first" (the default), "all", "last"
pattern, regex, fixed, coll, charclass
character vector defining search patterns; for more details refer to stringi-search
single logical value; should consecutive matches be merged into one string; stri_extract_all_charclass only
single logical value; if TRUE or NA, then a character matrix is returned; otherwise (the default), a list of character vectors is given, see Value; stri_extract_all_* only
single logical value; if FALSE, then a missing value will indicate that there was no match; stri_extract_all_* only
opts_collator, opts_fixed, opts_regex
a named list used to tune up a search engine's settings; see stri_opts_collator, stri_opts_fixed, and stri_opts_regex, respectively; NULL for default settings;

Vectorized over str and pattern. If you would like to extract regex capture groups individually, check out stri_match. stri_extract, stri_extract_all, stri_extract_first, and stri_extract_last are convenience functions. They just call stri_extract_*_*, depending on the arguments used. Relying on one of those underlying functions will make your code run slightly faster.


For stri_extract_all*, if simplify=FALSE (the default), then a list of character vectors is returned. Each list element represents the results of a separate search scenario. If a pattern is not found and omit_no_match=FALSE, then a character vector of length 1, with single NA value will be generated. Otherwise, i.e. if simplify is not FALSE, then stri_list2matrix with byrow=TRUE argument is called on the resulting object. In such a case, a character matrix with an appropriate number of rows (according to the length of str, pattern, etc.) is returned. Note that stri_list2matrix's fill argument is set to an empty string and NA, for simplify equal to TRUE and NA, respectively. stri_extract_first* and stri_extract_last*, on the other hand, return a character vector. A NA element indicates no match.

See Also

Other search_extract: stri_extract_all_boundaries, stri_match_all, stringi-search

  • stri_extract_all
  • stri_extract_first
  • stri_extract_last
  • stri_extract
  • stri_extract_all_charclass
  • stri_extract_first_charclass
  • stri_extract_last_charclass
  • stri_extract_all_coll
  • stri_extract_first_coll
  • stri_extract_last_coll
  • stri_extract_all_regex
  • stri_extract_first_regex
  • stri_extract_last_regex
  • stri_extract_all_fixed
  • stri_extract_first_fixed
  • stri_extract_last_fixed
stri_extract_all('XaaaaX', regex=c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
stri_extract_all('Bartolini', coll='i')
stri_extract_all('stringi is so good!', charclass='\\p{Zs}') # all whitespaces

stri_extract_all_charclass(c('AbcdeFgHijK', 'abc', 'ABC'), '\\p{Ll}')
stri_extract_all_charclass(c('AbcdeFgHijK', 'abc', 'ABC'), '\\p{Ll}', merge=FALSE)
stri_extract_first_charclass('AaBbCc', '\\p{Ll}')
stri_extract_last_charclass('AaBbCc', '\\p{Ll}')

stri_extract_all_coll(c('AaaaaaaA', 'AAAA'), 'a')
stri_extract_first_coll(c('Yy\u00FD', 'AAA'), 'y', strength=2, locale="sk_SK")
stri_extract_last_coll(c('Yy\u00FD', 'AAA'), 'y',  strength=1, locale="sk_SK")

stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
stri_extract_first_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
stri_extract_last_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))

stri_list2matrix(stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+')))
stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+'), simplify=TRUE)
stri_extract_all_regex('XaaaaX', c('\\p{Ll}', '\\p{Ll}+'), simplify=NA)

stri_extract_all_fixed("abaBAba", "Aba", case_insensitive=TRUE)
stri_extract_all_fixed("abaBAba", "Aba", case_insensitive=TRUE, overlap=TRUE)

Documentation reproduced from package stringi, version 1.1.5, License: file LICENSE

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