R: Determine Duplicated Elements

stri_duplicated {stringi} | R Documentation

## Determine Duplicated Elements

### Description

`stri_duplicated()` determines which strings in a character vector are duplicates of other elements.

`stri_duplicated_any()` determines if there are any duplicated strings in a character vector.

### Usage

    stri_duplicated(str, fromLast = FALSE, ..., opts_collator = NULL)

    stri_duplicated_any(str, fromLast = FALSE, ..., opts_collator = NULL)

### Arguments

`str` | a character vector
`fromLast` | a single logical value; indicating whether duplication should be considered from the reverse side
`...` | additional settings for `opts_collator`
`opts_collator` | a named list with ICU Collator's options as generated with `stri_opts_collator`, `NULL` for default collation options

### Details

Missing values are regarded as equal.

Unlike `duplicated` and `anyDuplicated`, these functions test for canonical equivalence of strings (and not whether the strings are just bytewise equal) Such operations are locale-dependent. Hence, `stri_duplicated` and `stri_duplicated_any` are significantly slower (but much better suited for natural language processing) than their base R counterpart.

See also `stri_unique` for extracting unique elements.

### Value

`stri_duplicated()` returns a logical vector of the same length as `str`. Each of its elements indicates whether a canonically equivalent string was already found in `str`.

`stri_duplicated_any()` returns a single non-negative integer. Value of 0 indicates that all the elements in `str` are unique. Otherwise, it gives the index of the first non-unique element.

### References

Collation - ICU User Guide, http://userguide.icu-project.org/collation

### See Also

Other locale_sensitive: `%s<%`, `stri_compare`, `stri_count_boundaries`, `stri_enc_detect2`, `stri_extract_all_boundaries`, `stri_locate_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 locale_sensitive: `%s<%`, `stri_compare`, `stri_count_boundaries`, `stri_enc_detect2`, `stri_extract_all_boundaries`, `stri_locate_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`

### Examples

    # In the following examples, we have 3 duplicated values,
    # "a" - 2 times, NA - 1 time
    stri_duplicated(c("a", "b", "a", NA, "a", NA))
    stri_duplicated(c("a", "b", "a", NA, "a", NA), fromLast=TRUE)
    stri_duplicated_any(c("a", "b", "a", NA, "a", NA))

    # compare the results:
    stri_duplicated(c("\u0105", stri_trans_nfkd("\u0105")))
    duplicated(c("\u0105", stri_trans_nfkd("\u0105")))

    stri_duplicated(c("gro\u00df", "GROSS", "Gro\u00df", "Gross"), strength=1)
    duplicated(c("gro\u00df", "GROSS", "Gro\u00df", "Gross"))

[Package stringi version 1.2.4 Index]