[R] mapping array

[Bill.Venables at csiro.au]

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

______________________________________________
R-help at r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.