Chapter 12 assign column names

colnames(df) <- cnames

names(df)

## [1] "patient" "age"     "weight"  "bp"      "rating"  "test"

names(df) <- toupper(names(df))

names(df)

## [1] "PATIENT" "AGE"     "WEIGHT"  "BP"      "RATING"  "TEST"

names(df) <- tolower(names(df))

names(df)

## [1] "patient" "age"     "weight"  "bp"      "rating"  "test"