R: Encode character variables into numeric

Question

In R code I have a character variable var that has values \"AA\", \"AB\", \"AC\", etc.

str(var)
chr [1:17003] \"AA\" \"AA\" \"AA\" \"AA\" \"AB\"         


        

Answer 1

You can convert the string to a factor and then to numeric.

x <- c("AA", "AB", "AB", "AC", "AA", "XY")
as.numeric(as.factor(x))
# [1] 1 2 2 3 1 4

Alternatively, you can use match and unique:

match(x, unique(x))
# [1] 1 2 2 3 1 4