[R] repeating values in an index two by two

[Federico Calboli]

Hi,

first off, thanks for the suggestion.  I managed to solve it by doing:

IND = rep(c(T,T,F,F), 5)
X = rep(NA, 20)
X[IND] = 1:10
X[!IND] = 1:10

which avoids any function -- I think mapply, apply etc call a for loop internally, which I'd rather avoid.

BW

F



On 11 Nov 2013, at 12:35, andrija djurovic <djandrija at gmail.com> wrote:

> Hi. Here are two approaches:
> 
> c(mapply(function(x,y) rep(c(x,y), 2), (1:10)[c(T,F)], (1:10)[c(F,T)]))
> 
> c(tapply(1:10, rep(1:(10/2), each=2), rep, 2), recursive=T)
> 
> Andrija
> 
> 
> 
> 
> 
> On Mon, Nov 11, 2013 at 1:11 PM, Federico Calboli <f.calboli at imperial.ac.uk> 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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