Dear Christy,
Take a look at
http://www.nabble.com/Efficient-way-to-fill-a-matrix-to20351720.html#a20351720
Here are three options to do what you want:
# Data set
mydata=read.table(textConnection("
point1 point2 distance
1 1 0
1 2 4
2 2 0
2 1 4"),header=TRUE)
closeAllConnections()
# Option 1
with(mydata,tapply(distance,list(point1,point2),"[[",1))
# Option 2
M <- matrix(,2,2)
attach(mydata)
M[cbind(point1,point2)]<-distance
# Option 3
library(reshape)
cast(mydata, point1~point2)
HTH,
Jorge
On Sun, Nov 9, 2008 at 7:11 PM, skinny c <[EMAIL PROTECTED]> wrote:
> Hello,
> I am trying to convert list of pairwise distances to a distance matrix for
> spatial analysis (kriging). For instance, I have something like this for
> each pair pf points, and I want to convert it to a matrix:
>
> point1 point2 distance
> 1 1 0
> 1 2 4
> 2 2 0
> 2 1 4
>
> Please let me know if there is a function or method that can do this.
>
> Thanks,
> Christy
>
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>
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