On Nov 17, 2012, at 10:07 AM, benjamin_jarrett wrote:
> Hi David,
>
> Thanks for replying. Unfortunately I can't get it to work. Here is some
> (very simplified) data to help illustrate my problem.
>
> ind <- c('1','2','3','4')
> fam <- c('1','2','1','2')
> data <- data.frame(ind,fam)
>
> ind is the unique ID for each individual, and fam is which family the
> individual came from. Using combn(ind, 2) matches all of the individuals. Is
> there any way I could get combn to pair individuals up based on a different
> family number, so with the above data individual 1 would be paired with
> individual 2 or 4.
Please include context (and _do_ read the Posting Guide.) This is the
suggestion I made before:
> See if this helps:
>
> combn( 1:5, 2, FUN = function(b){
> if (max (b) < 4 ) { b } else { c(NA,NA) } } )
> [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
> [1,] 1 1 NA NA 2 NA NA NA NA NA
> [2,] 2 3 NA NA 3 NA NA NA NA NA
And this is how to apply it to the example:
combn( row.names(data), 2, FUN = function(b){
if (data[b[1], "fam" ] != data[b[2], "fam"] ) { b } else {
c(NA,NA) } } )
[,1] [,2] [,3] [,4] [,5] [,6]
[1,] "1" NA "1" "2" NA "3"
[2,] "2" NA "4" "3" NA "4"
--
David Winsemius, MD
Alameda, CA, USA
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