How to recode values in a variable in a data frame in R

Asked May 06 '19 at 07:57

Active May 06 '19 at 07:57

Viewed 31 times

I have a datatable, dataframe which has a variable: grade_c:Factor w/8 Level. 0, A, B, C, D, E, F, NA

And I want to change the variables to ->

0-> NA

A-> 1

B-> 2

C-> 3

...

F-> 6

I saw that I can recode variables with this code:

NonTestMergeV$grade_c[NonTestMergeV$grade_c=="A"] <- 1

But when I try it I get this warning. And nothing changes...

Warning message: In [<-.factor(*tmp*, NonTestMergeV$grade_c == "A", value = c(NA, : invalid factor level, NA generated

Any help on how to get the desired result would be helpful. Thank you!

asked May 06 '19 at 07:57

Alex Rika

change them to characters first by doing `NonTestMergeV$grade_c <- as.character(NonTestMergeV$grade_c)` and then use any of the methods in the link. – Ronak Shah May 06 '19 at 08:07
@RonakShah I dont understand the links answers. This doesnt answer my question. – Alex Rika May 06 '19 at 08:17
@RonakShah What does dictionary has to do with my numeric values? – Alex Rika May 06 '19 at 08:17
did you convert `grade_c` column to character as mentioned above ? – Ronak Shah May 06 '19 at 08:19
Yes. Still dont get how to change them... – Alex Rika May 06 '19 at 08:22
do `map = setNames(c(NA, 1:5), c(0,LETTERS[1:5]))` and then `NonTestMergeV$grade_c <- map[NonTestMergeV$grade_c]` – Ronak Shah May 06 '19 at 08:29

0 Answers0