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Determine the Width of Code Points

Source: R/length.R
stri_width.Rd

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

Value

Returns an integer vector of the same length as str.

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.

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()

Author

Marek Gagolewski and other contributors

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