[R] Loop elimination question

[BXC (Bendix Carstensen)]

How  about:

> dim
[1] 3 1 4 1 5
> N <- length(dim)
> one <- rep(c(3,4),N)
> two <- c(rep(1,N),dim)
> three <- rep(1:N,rep(2,N))+N*rep(0:1,N)
> rep(one,two[three])
 [1] 3 4 4 4 3 4 3 4 4 4 4 3 4 3 4 4 4 4 4

----------------------
Bendix Carstensen
Senior Statistician
Steno Diabetes Centre
Niels Steensens Vej 2
DK-2820 Gentofte
Denmark
tel: +45 44 43 87 38
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fax: +45 44 43 73 13
bxc at novo.dk
www.biostat.ku.dk/~bxc
----------------------


> -----Original Message-----
> From: Murray Jorgensen [mailto:maj at waikato.ac.nz]
> Sent: 1. november 2000 09:55
> To: r-help at stat.math.ethz.ch
> Subject: [R] Loop elimination question
> 
> 
> I want to make a vector built up from several parts. Each 
> part consists of 3
> followed by a variable number of 4s. The number of 4s is 
> given by a vector
> called dim, say
> 
> dim <- c(3,1,4,1,5)
> 
> From this I want to produce 
> 
> 3 4 4 4 3 4 3 4 4 4 4 3 4 3 4 4 4 4 4
> 
> Now the following code seems to work
> 
> type <- numeric(0)
> for (j in seq(along=dim)) {
>       type <- c(type,3,rep(4,dim[j]))}
> 
> and I won't really need it to work for very large dim vectors 
> so you could say
> my problem is solved. I am wondering, though, if the loop can 
> be eliminated.
> 
> 
> 
> Murray Jorgensen,  Department of Statistics,  U of Waikato, 
> Hamilton, NZ
> -----[+64-7-838-4773]---------------------------[maj at waikato.a
> c.nz]-----
> "Doubt everything or believe everything:these are two equally 
> convenient
> strategies. With either we dispense with the need to think."
> http://www.stats.waikato.ac.nz/Staff/maj.html          - 
> Henri Poincare'
> 
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