Question

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R: generate a repeating sequence based on vector

To create the vector 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 is easy in one line, just type this into the command line and the appropriate output comes out immediately:

c(rep(1:3, 5))

But is there a similarly easy way to produce the vector 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5 ?

The pattern of the repetition is different but it’s not obvious to me why it’s not amenable to a very simple solution. It’s possible to do this with a “for” loop without too much difficulty, but can it be all compressed into one “line”?

Answer 1

You need the each parameter within rep:

> rep(1:5, each = 3)
 [1] 1 1 1 2 2 2 3 3 3 4 4 4 5 5 5