repeating values in an index two by two
Here's a rather extreme solution: foo<-rep(1:6,each=2) Rgames> foo [1] 1 1 2 2 3 3 4 4 5 5 6 6 Rgames> foo[rep(c(1,3,2,4),3)+rep(c(0,4,8),each=4)] [1] 1 2 1 2 3 4 3 4 5 6 5 6 In the general case, then, it would be something like foo<- rep(1:N, each = 2) # foo is of length(2*N) foo[rep(c(1,3,2,4),2*N/4 + rep( seq(0, 3*N/4,by=4),each=4)] Note that the refolding requires the sequence to have length a multiple of 4. Patrick Burns wrote
f1
function(x) {
one <- matrix(1:x, nrow=2)
as.vector(rbind(one, one))
}
<environment: 0x000000000daaf1c0>
> f1(8)
[1] 1 2 1 2 3 4 3 4 5 6 5 6 7 8 7 8 Pat On 11/11/2013 12:11, Federico Calboli wrote:
Hi All, I am trying to create an index that returns something like 1,2,1,2,3,4,3,4,5,6,5,6,7,8,7,8 and so on and so forth until a predetermined value (which is obviously even). I am trying very hard to avoid for loops or for loops front ends. I'd be obliged if anybody could offer a suggestion. BW F
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-- Patrick Burns
pburns at .seanet
twitter: @burnsstat @portfolioprobe http://www.portfolioprobe.com/blog http://www.burns-stat.com (home of: 'Impatient R' 'The R Inferno' 'Tao Te Programming')
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