Get a seq() in R with alternating steps

Question

The seq function in R would give me a sequence from x to y with a constant step m:

seq(x, y, m)
         


        

Answer 1

perfect example of recycling vectors in R

# 1. 
x = 1; y = 19; m1 = 2; m2 = 4
(x:y)[c(TRUE, rep(FALSE, m1-1), TRUE, rep(FALSE,m2-1))]
# [1]  1  3  7  9 13 15 19
# 2.
x = 3; y = 56; m1 = 7; m2 = 10
(x:y)[c(TRUE, rep(FALSE, m1-1), TRUE, rep(FALSE,m2-1))]
# [1]  3 10 20 27 37 44 54