[R] mapping array

[Gregory Ryslik]

Worked great, thanks! 
On Sep 11, 2010, at 8:26 PM, <Bill.Venables at csiro.au> <Bill.Venables at csiro.au> wrote:

> Is this the kind of thing you are talking about?
> 
> ### 8< cut here 8< ###
> A <- rep(NA, 100)
> B <- sort(runif(25))
> C <- sort(sample(1:100, 25))
> 
> A[C] <- B
> B
> C
> A
> ### 8< cut here 8< ###
> 
> 
> (The sorting is not necessary.  It's only there to make checking what happened easier.)
> 
> 
> -----Original Message-----
> From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Gregory Ryslik
> Sent: Sunday, 12 September 2010 8:54 AM
> To: r-help at r-project.org
> Subject: [R] mapping array
> 
>  Hi,
> 
> Suppose I have array A with 100 elements all filled in with "N/A". Array 
> B has 25 elements with actual values. Lastly, I have array C that 
> provides a map of where to put the elements from array A into array B. 
> Thus C would say put element 1 from B into element 3 from array A.
> 
> I realize I can do this with a for loop. However, because I'm doing a 
> random forest with this, I'd like to avoid a for loop because it would 
> take significantly more time.
> 
> Thanks,
> Greg
> 
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