On Mon, Jun 18, 2012 at 01:24:21AM +0800, 李红旺 wrote:
> > a<-c(1,4)
> > a
> [1] 1 4
> > b<-a*5
> > b
> [1] 5 20
>
> a is a very long vector , how can i get c(1:5,4:20)? i do not want to
> use a loop.
Hi.
How large are the numbers in a? If max(a) is not too large, try
the following.
a <- c(1, 4, 3, 1)
ma <- max(a)
b <- matrix(a, nrow=4*ma+1, ncol=length(a), byrow=TRUE) +
matrix(0:(4*ma), nrow=4*ma+1, ncol=length(a))
out <- c(b[b <= rep(5*a, each=4*ma+1)])
out
[1] 1 2 3 4 5 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 3 4 5
[26] 6 7 8 9 10 11 12 13 14 15 1 2 3 4 5
Hope this helps.
Petr Savicky.
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