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, tools:::Rd_expr_doi("10.18637/jss.v103.i02")
Other transform:
stri_trans_char()
,
stri_trans_general()
,
stri_trans_nfc()
,
stri_trans_tolower()