I have a mixed dataframe of character and numeric variables.
city,hs_cd,sl_no,col_01,col_02,col_03 Austin,1,2,,46,Female Austin,1,3,,32,Male Austin,1,4,,27,
From the dplyr package you can also use the mutate_all() function in combination with toupper(). This will affect both character and factor classes.
dplyr
mutate_all()
toupper()
library(dplyr) df <- mutate_all(df, funs=toupper)