[R] generate repeats of a vector's elements

Antje niederlein-rstat at yahoo.de
Fri Jul 18 14:40:50 CEST 2008

I would do it like this but I'm curious to see whether it can be easier solved :-)

b <- c(1:10)
vector_list <- lapply(1:length(b), FUN = function(x) { b[1:x] }))

(for everything in a large vector just apply "unlist" to the "vector_list")


Chaofeng Kou schrieb:
> Dear all,
> I have got a question for generating repeats of a vector's elements.
> Please don't hesitate to email me back and say that it is very easy
> although I can't find a method to solve it.
> If I have a n-vector b, whose elements are b[1], b[2], ..., b[n], how
> can I generate such a vector
>   b[1],   b[1], b[2],   b[1], b[2], b[3],   b[1], b[2], b[3], b[4],
> ......,   b[1], b[2], ..., b[n]
> which contains n(n+1)/2 elements.
> Thanks very much.
> Regards
> Chaofeng Kou
> 	[[alternative HTML version deleted]]
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