[R] pairing data using combn with criteria

[arun]

HI,


If the order of individuals are changed or if some individuals are missing, this method may need modification.

ind <- c('1','3','4','8')
  fam <- c('1','2','1','2')
  dat1 <- data.frame(ind,fam)
 combn( row.names(dat1), 2, FUN = function(b){
                 if (dat1[b[1], "fam" ] != dat1[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" 

 row.names(dat1)<-dat1$ind
  combn( row.names(dat1), 2, FUN = function(b){
                  if (dat1[b[1], "fam" ] != dat1[b[2], "fam"] ) { b } else { c(NA,NA) } } )
#     [,1] [,2] [,3] [,4] [,5] [,6]
#[1,] "1"  NA   "1"  "3"  NA   "4" 
#[2,] "3"  NA   "8"  "4"  NA   "8" 


A.K.
----- Original Message -----
From: David Winsemius <dwinsemius at comcast.net>
To: benjamin_jarrett <bjmjarrett at gmail.com>
Cc: r-help at r-project.org
Sent: Saturday, November 17, 2012 6:36 PM
Subject: Re: [R] pairing data using combn with criteria


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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