Vector recycling concept in R

user_14512983 0
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I am trying to understand the working of vector recycling in R. I have 2 vectors

c(2,4,6)

and

c(1,2)

And I want to use the rep() to produce an output as follows:

[1]  2  4  6  4  8 12

based on what I understand from ?rep() is that there are times and each parameters which do the operations which I tried.

> rep(c(2,4,6), times=2)
[1] 2 4 6 2 4 6

But I also see the first vector is multiplied by the first element of the second vector and then to the second element of the second vector. Not sure how to proceed with it.

r
1 Answers

You can use:

rep(c(2,4,6), 2) * rep(c(1,2), each=3)
#[1]  2  4  6  4  8 12

or with auto recycling:

c(2,4,6) * rep(c(1,2), each=3)
#[1]  2  4  6  4  8 12

Alternative outer could be used:

c(outer(c(2,4,6), c(1,2)))
#[1]  2  4  6  4  8 12

Also crossprod could be used:

c(crossprod(t(c(2,4,6)), c(1,2)))
#[1]  2  4  6  4  8 12

Or %*%:

c(c(2,4,6) %*% t(c(1,2)))
#[1]  2  4  6  4  8 12
user_104885040
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