Convert c('a' 'c', 'b') to c('a', 'a', 'c', 'c', 'b', 'b') in R?

Question

Given a vector of variables, transform the vector so that each variable is repeated

For example, I could

sort(rep(c('a', 'c', 'b')))

except that I don't want to sort them; I want it to return c('a', 'a', 'c', 'c', 'b', 'b')

Answer 1

Use ?rep

vec <- c('a', 'b', 'c')
rep(vec, each = 2)