Make a column with duplicated values unique in a dataframe

Question

I have a dataframe where a column has duplicate values like

employee <- data.frame(name = c(\'John\', \'Joe\', \'Mat\', \'John\', \'Joe\'), 
                     


        

Answer 1

We can use make.names with unique=TRUE. By default, a . will be appended before the suffix numbers, and that can be replaced by _ using sub

 employee$name <- sub('[.]', '_', make.names(employee$name, unique=TRUE))

Or a better option suggested by @DavidArenburg. If the name column is factor class, convert the input column to character class (as.character) before applying the make.unique

 make.unique(as.character(employee$name), sep = "_")
 #[1] "John"   "Joe"    "Mat"    "John_1" "Joe_1"