Extract every nth element of a vector?

Question

I would like to create a vector in which each element is the `i+6th` element of another vector.For example, in a vector of length 120 I want to create another vector of length 20 in which each element is value `i, i+6, i+12, i+18...` of the initial vector, i.e. I want to extract every 6th element of the original.

Answer 1

To do this, use the following code that I used in R:

fun <- 1:60

> fun[1:(i+6) == (i+6)]

[1] 7 14 21 28 35 42 49 56

What this code is telling R to do is to subset the vector, fun, between 1 and (i+6) and only return a value is the value is equal to (i +6).

This subset of the function can be assigned to a vector as follows:

>fun2 <- fun[1:(i+6) == (i+6)]