Letter casing functions are available in the stringi package on CRAN.
library(stringi)
lowercase = stri_trans_tolower(str)
uppercase = stri_trans_toupper(str)
titlecase = stri_trans_totitle(str)- Requires: stringi
- Docs: http://docs.rexamine.com/R-man/stringi/stri_trans_casemap.html