Hide navigation sidebar
Hide table of contents sidebar
Back to top
Edit this page
Toggle table of contents sidebar

# stri_unique: Extract Unique Elements

## Description

This function returns a character vector like `str`, but with duplicate elements removed.

## Usage

    stri_unique(str, ..., opts_collator = NULL)

## Arguments

`str` | a character vector
`...` | additional settings for `opts_collator`
`opts_collator` | a named list with ICU Collator’s options, see `stri_opts_collator`, `NULL` for default collation options

## Details

As usual in stringi, no attributes are copied. Unlike `unique`, this function tests for canonical equivalence of strings (and not whether the strings are just bytewise equal). Such an operation is locale-dependent. Hence, `stri_unique` is significantly slower (but much better suited for natural language processing) than its base R counterpart.

See also `stri_duplicated` for indicating non-unique elements.

## Value

Returns a character vector.

## Author(s)

Marek Gagolewski and other contributors

## References

Collation - ICU User Guide, https://unicode-org.github.io/icu/userguide/collation/

## See Also

The official online manual of stringi at https://stringi.gagolewski.com/

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

Other locale_sensitive: `%s<%()`, `about_locale`, `about_search_boundaries`, `about_search_coll`, `stri_compare()`, `stri_count_boundaries()`, `stri_duplicated()`, `stri_enc_detect2()`, `stri_extract_all_boundaries()`, `stri_locate_all_boundaries()`, `stri_opts_collator()`, `stri_order()`, `stri_rank()`, `stri_sort()`, `stri_sort_key()`, `stri_split_boundaries()`, `stri_trans_tolower()`, `stri_wrap()`

## Examples

    # normalized and non-Unicode-normalized version of the same code point:
    stri_unique(c('\u0105', stri_trans_nfkd('\u0105')))
    ## [1] "ą"
    unique(c('\u0105', stri_trans_nfkd('\u0105')))
    ## [1] "ą" "ą"
    stri_unique(c('gro\u00df', 'GROSS', 'Gro\u00df', 'Gross'), strength=1)
    ## [1] "groß"