Locate Occurrences of a Pattern

These functions may be used, e.g., to find the indexes (positions) where there is a match to some pattern. The functions stri_locate_all_* locate all the matches. stri_locate_first_* and stri_locate_last_* give the first or the last matches, respectively.

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

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

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

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

stri_locate_all_charclass(str, pattern, merge = TRUE, omit_no_match = FALSE)

stri_locate_first_charclass(str, pattern)

stri_locate_last_charclass(str, pattern)

stri_locate_all_coll(str, pattern, omit_no_match = FALSE, ..., opts_collator = NULL)

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

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

stri_locate_all_regex(str, pattern, omit_no_match = FALSE, ..., opts_regex = NULL)

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

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

stri_locate_all_fixed(str, pattern, omit_no_match = FALSE, ..., opts_fixed = NULL)

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

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


character vector; strings to search in


supplementary arguments passed to the underlying functions, including additional settings for opts_collator, opts_regex, opts_fixed, and so on


single string; one of: "first" (the default), "all", "last"

pattern, regex, fixed, coll, charclass

character vector; search patterns; for more details refer to stringi-search


single logical value; indicates whether consecutive sequences of indexes in the resulting matrix should be merged; stri_locate_all_charclass only


single logical value; if FALSE, then two missing values will indicate that there was no match; stri_locate_all_* only

opts_collator, opts_fixed, opts_regex

a named list used to tune up the search engine's settings; see stri_opts_collator, stri_opts_fixed, and stri_opts_regex, respectively; NULL for the defaults


Vectorized over str and pattern (with recycling of the elements in the shorter vector if necessary). This allows to, for instance, search for one pattern in each given string, search for each pattern in one given string, and search for the i-th pattern within the i-th string.

The matches may be extracted by calling stri_sub or stri_sub_all. Alternatively, you may call stri_extract directly.

stri_locate, stri_locate_all, stri_locate_first, and stri_locate_last are convenience functions. They just call stri_locate_*_*, depending on the arguments used.


For stri_locate_all_*, a list of integer matrices is returned. Each list element represents the results of a separate search scenario. The first column gives the start positions of the matches, and the second column gives the end positions. Moreover, you may get two NAs in one row for no match (if omit_no_match is FALSE) or NA arguments.

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

For stri_locate_*_regex, if the match is of zero length, end will be one character less than start.

See Also

Other search_locate: stri_locate_all_boundaries, stringi-search

Other indexing: stri_locate_all_boundaries, stri_sub_all, stri_sub

  • stri_locate_all
  • stri_locate_first
  • stri_locate_last
  • stri_locate
  • stri_locate_all_charclass
  • stri_locate_first_charclass
  • stri_locate_last_charclass
  • stri_locate_all_coll
  • stri_locate_first_coll
  • stri_locate_last_coll
  • stri_locate_all_regex
  • stri_locate_first_regex
  • stri_locate_last_regex
  • stri_locate_all_fixed
  • stri_locate_first_fixed
  • stri_locate_last_fixed
   regex=c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
stri_locate_all('Bartolini', fixed='i')
stri_locate_all('a b c', charclass='\\p{Zs}') # all white spaces

stri_locate_all_charclass(c('AbcdeFgHijK', 'abc', 'ABC'), '\\p{Ll}')
stri_locate_all_charclass(c('AbcdeFgHijK', 'abc', 'ABC'), '\\p{Ll}', merge=FALSE)
stri_locate_first_charclass('AaBbCc', '\\p{Ll}')
stri_locate_last_charclass('AaBbCc', '\\p{Ll}')

stri_locate_all_coll(c('AaaaaaaA', 'AAAA'), 'a')
stri_locate_first_coll(c('Yy\u00FD', 'AAA'), 'y', strength=2, locale="sk_SK")
stri_locate_last_coll(c('Yy\u00FD', 'AAA'), 'y', strength=1, locale="sk_SK")

pat <- stri_paste("\u0635\u0644\u0649 \u0627\u0644\u0644\u0647 ",
                  "\u0639\u0644\u064a\u0647 \u0648\u0633\u0644\u0645XYZ")
stri_locate_last_coll("\ufdfa\ufdfa\ufdfaXYZ", pat, strength = 1)

stri_locate_all_fixed(c('AaaaaaaA', 'AAAA'), 'a')
stri_locate_all_fixed(c('AaaaaaaA', 'AAAA'), 'a', case_insensitive=TRUE, overlap=TRUE)
stri_locate_first_fixed(c('AaaaaaaA', 'aaa', 'AAA'), 'a')
stri_locate_last_fixed(c('AaaaaaaA', 'aaa', 'AAA'), 'a')

#first row is 1-2 like in locate_first
stri_locate_all_fixed('bbbbb', 'bb')
stri_locate_first_fixed('bbbbb', 'bb')

# but last row is 3-4, unlike in locate_last,
# keep this in mind [overlapping pattern match OK]!
stri_locate_last_fixed('bbbbb', 'bb')

   c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
   c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))
   c('\\p{Ll}', '\\p{Ll}+', '\\p{Ll}{2,3}', '\\p{Ll}{2,3}?'))

# Use regex positive-lookahead to locate overlapping pattern matches:
stri_locate_all_regex("ACAGAGACTTTAGATAGAGAAGA", "(?=AGA)")
# note that start > end here (match of 0 length)

# }
Documentation reproduced from package stringi, version 1.4.3, License: file LICENSE

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