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# stri_width: Determine the Width of Code Points

## Description

Approximates the number of text columns the ‘cat()’ function might use to print a string using a mono-spaced font.

## Usage

    stri_width(str)

## Arguments

`str` | character vector or an object coercible to

## Details

The Unicode standard does not formalize the notion of a character width. Roughly based on http://www.cl.cam.ac.uk/~mgk25/ucs/wcwidth.c, https://github.com/nodejs/node/blob/master/src/node_i18n.cc, and UAX #11 we proceed as follows. The following code points are of width 0:

- code points with general category (see stringi-search-charclass) `Me`, `Mn`, and `Cf`),

- `C0` and `C1` control codes (general category `Cc`) - for compatibility with the `nchar` function,

- Hangul Jamo medial vowels and final consonants (code points with enumerable property `UCHAR_HANGUL_SYLLABLE_TYPE` equal to `U_HST_VOWEL_JAMO` or `U_HST_TRAILING_JAMO`; note that applying the NFC normalization with `stri_trans_nfc` is encouraged),

- ZERO WIDTH SPACE (U+200B),

Characters with the `UCHAR_EAST_ASIAN_WIDTH` enumerable property equal to `U_EA_FULLWIDTH` or `U_EA_WIDE` are of width 2.

Most emojis and characters with general category So (other symbols) are of width 2.

SOFT HYPHEN (U+00AD) (for compatibility with `nchar`) as well as any other characters have width 1.

## Value

Returns an integer vector of the same length as `str`.

## Author(s)

Marek Gagolewski and other contributors

## References

East Asian Width – Unicode Standard Annex #11, https://www.unicode.org/reports/tr11/

## 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 length: `%s$%()`, `stri_isempty()`, `stri_length()`, `stri_numbytes()`, `stri_pad_both()`, `stri_sprintf()`

## Examples

    stri_width(LETTERS[1:5])
    ## [1] 1 1 1 1 1
    stri_width(stri_trans_nfkd('\u0105'))
    ## [1] 1
    stri_width(stri_trans_nfkd('\U0001F606'))
    ## [1] 2
    stri_width( # Full-width equivalents of ASCII characters:
       stri_enc_fromutf32(as.list(c(0x3000, 0xFF01:0xFF5E)))
    )
    ##  [1] 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
    ## [39] 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
    ## [77] 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
    stri_width(stri_trans_nfkd('\ubc1f')) # includes Hangul Jamo medial vowels and final consonants
    ## [1] 2