我有mixed dataframe个字符和数字变量.
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,Male
Austin,1,5,,20,Female
Austin,2,2,,42,Female
Austin,2,1,,52,Male
Austin,2,3,,25,Male
Austin,2,4,,22,Female
Austin,3,3,,30,Female
Austin,3,1,,65,Female
我想把数据框中的所有小写字符转换成大写.有没有办法在一次拍摄中做到这一点,而不必在每个字符变量上重复这样做?