Re: extract row name of matrix

[Sundar Dorai-Raj <sundar.dorai-raj@pdf.com>]

Sarah Henderson wrote:
> Hello to all --
>
> My apologies for what I know to be an elementary question, but cannot 
> seem to find the answer to.
> I would like to extract the row name of a matrix where the third column 
> has it's maximum value.  I know that dimnames(matrix)[1] gives the row 
> names and that max(matrix[,3]) gives the maximum in the third column, 
> but I just can't figure out how to put the two together.  I tried 
> dimnames(matrix)[1[max(matrix)[,3]] but that didn't work.
> A point in the right direction would be much appreciated.  I'm using 
> S-Plus 6.2 in Windows.
> Thanks,
>
> Sarah
You want something that returns the index of the maximum.

which.max <- function(x) which(x == max(x))
dimnames(m)[[1]][which.max(m[, 3])]

HTH,

--sundar