Question

I am embrased to ask this simple question, but I could not figure it out.

I have a variable

names <- c("M1", "K2L", "C2L", "N", "R_1_2", "CLA", "T123") # the real dataset has > 6000 valriables 

I want to double names and add alphabets “a” and “b” and the output (consider order too) would look like the following:

M1a, M1b, K2La, K2Lb, C2La, C2Lb, Na, Nb, R_1_2a, R_1_2b, CLAa, CLAb, T123a, T123b 

Thanks for the help:

Answer 1

Use rep with the each argument to repeat each name. Then use paste to combine them with the suffix.

paste(rep(names, each = 2), c("a", "b"), sep = "")

Let’s look at that again in slow motion:

suffixes <- c("a", "b")  # or letters[1:2] if you're feeling fancy
n_suffixes <- length(suffixes)
repeated_names <- rep(names, each = n_suffixes)
final_names <- paste(repeated_names, suffixes, sep = "")

---

Fancy alternate version using outer products:

as.vector(t(outer(names, suffixes, paste, sep = "")))

Though I think this is more for showing off, since it’s less readable.