How to map a column through a dictionary in R

Question

I have a data frame in R. One column of this data frame takes values from 1 to 6. I have another data frame that maps this column. There is some way to substitute the values

Answer 1

To use this type of map/dictionary to create a new data frame column, you can also use the match method:

snape_gradebook_df<-data_frame(students=c("Harry", "Hermione", "Ron", "Neville", "Ginny", "Luna", "Draco", "Cho"),
           numeric_grade=c(4,2,2,3,4,1,4,4))
grade_map<-data_frame(numbers=c(1,2,3,4), letters=c("A", "B", "C", "D"),
                    stringsAsFactors = FALSE)
snape_gradebook_df['letter_grade']<-grade_map$letters[match(old_list, grade_map$numbers)]

I'm not sure the advantages/disadvantages of setNames vs match - just thought I would share another possible solution.