stringi (version 1.8.4)

stri_replace_all: Replace Pattern Occurrences


These functions replace, with the given replacement string, every/first/last substring of the input that matches the specified pattern.


stri_replace_all(str, replacement, ..., regex, fixed, coll, charclass)

stri_replace_first(str, replacement, ..., regex, fixed, coll, charclass)

stri_replace_last(str, replacement, ..., regex, fixed, coll, charclass)

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

stri_replace_all_charclass( str, pattern, replacement, merge = FALSE, vectorize_all = TRUE, vectorise_all = vectorize_all )

stri_replace_first_charclass(str, pattern, replacement)

stri_replace_last_charclass(str, pattern, replacement)

stri_replace_all_coll( str, pattern, replacement, vectorize_all = TRUE, vectorise_all = vectorize_all, ..., opts_collator = NULL )

stri_replace_first_coll(str, pattern, replacement, ..., opts_collator = NULL)

stri_replace_last_coll(str, pattern, replacement, ..., opts_collator = NULL)

stri_replace_all_fixed( str, pattern, replacement, vectorize_all = TRUE, vectorise_all = vectorize_all, ..., opts_fixed = NULL )

stri_replace_first_fixed(str, pattern, replacement, ..., opts_fixed = NULL)

stri_replace_last_fixed(str, pattern, replacement, ..., opts_fixed = NULL)

stri_replace_all_regex( str, pattern, replacement, vectorize_all = TRUE, vectorise_all = vectorize_all, ..., opts_regex = NULL )

stri_replace_first_regex(str, pattern, replacement, ..., opts_regex = NULL)

stri_replace_last_regex(str, pattern, replacement, ..., opts_regex = NULL)


All the functions return a character vector.



character vector; strings to search in


character vector with replacements for matched patterns


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; should consecutive matches be merged into one string; stri_replace_all_charclass only


single logical value; should each occurrence of a pattern in every string be replaced by a corresponding replacement string?; stri_replace_all_* only


alias of vectorize_all

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


Marek Gagolewski and other contributors


By default, all the functions are vectorized over str, pattern, replacement (with recycling of the elements in the shorter vector if necessary). Input that is not part of any match is left unchanged; each match is replaced in the result by the replacement string.

However, for stri_replace_all*, if vectorize_all is FALSE, then each substring matching any of the supplied patterns is replaced by a corresponding replacement string. In such a case, the vectorization is over str, and - independently - over pattern and replacement. In other words, this is equivalent to something like for (i in 1:npatterns) str <- stri_replace_all(str, pattern[i], replacement[i]. Note that you must set length(pattern) >= length(replacement).

In case of stri_replace_*_regex, the replacement string may contain references to capture groups (in round parentheses). References are of the form $n, where n is the number of the capture group ($1 denotes the first group). For the literal $, escape it with a backslash. Moreover, ${name} are used for named capture groups.

Note that stri_replace_last_regex searches from start to end, but skips overlapping matches, see the example below.

stri_replace, stri_replace_all, stri_replace_first, and stri_replace_last are convenience functions; they just call stri_replace_*_* variants, depending on the arguments used.

If you wish to remove white-spaces from the start or end of a string, see stri_trim.

See Also

The official online manual of stringi at

Gagolewski M., stringi: Fast and portable character string processing in R, Journal of Statistical Software 103(2), 2022, 1-59, tools:::Rd_expr_doi("10.18637/jss.v103.i02")

Other search_replace: about_search, stri_replace_rstr(), stri_trim_both()


Run this code
stri_replace_all_charclass('aaaa', '[a]', 'b', merge=c(TRUE, FALSE))

stri_replace_all_charclass('a\nb\tc   d', '\\p{WHITE_SPACE}', ' ')
stri_replace_all_charclass('a\nb\tc   d', '\\p{WHITE_SPACE}', ' ', merge=TRUE)

s <- 'Lorem ipsum dolor sit amet, consectetur adipisicing elit.'
stri_replace_all_fixed(s, ' ', '#')
stri_replace_all_fixed(s, 'o', '0')

stri_replace_all_fixed(c('1', 'NULL', '3'), 'NULL', NA)

stri_replace_all_regex(s, ' .*? ', '#')
stri_replace_all_regex(s, '(el|s)it', '1234')
stri_replace_all_regex('abaca', 'a', c('!', '*'))
stri_replace_all_regex('123|456|789', '(\\p{N}).(\\p{N})', '$2-$1')
stri_replace_all_regex(c('stringi R', 'REXAMINE', '123'), '( R|R.)', ' r ')

# named capture groups are available since ICU 55
if (FALSE) {
stri_replace_all_regex('words 123 and numbers 456',
   '(?[0-9]+)', '!${numbers}!')

# Compare the results:
stri_replace_all_fixed('The quick brown fox jumped over the lazy dog.',
     c('quick', 'brown', 'fox'), c('slow',  'black', 'bear'), vectorize_all=TRUE)
stri_replace_all_fixed('The quick brown fox jumped over the lazy dog.',
     c('quick', 'brown', 'fox'), c('slow',  'black', 'bear'), vectorize_all=FALSE)

# Compare the results:
stri_replace_all_fixed('The quicker brown fox jumped over the lazy dog.',
     c('quick', 'brown', 'fox'), c('slow',  'black', 'bear'), vectorize_all=FALSE)
stri_replace_all_regex('The quicker brown fox jumped over the lazy dog.',
     '\\b'%s+%c('quick', 'brown', 'fox')%s+%'\\b', c('slow',  'black', 'bear'), vectorize_all=FALSE)

# Searching for the last occurrence:
# Note the difference - regex searches left to right, with no overlaps.
stri_replace_last_fixed("agAGA", "aga", "*", case_insensitive=TRUE)
stri_replace_last_regex("agAGA", "aga", "*", case_insensitive=TRUE)

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