[R] Second largest element from each matrix row

[Peter Ehlers]

On 2011-04-26 05:01, Lars Bishop wrote:
> Hi,
>
> I need to extract the second largest element from each row of a
> matrix. Below is my solution, but I think there should be a more efficient
> way to accomplish the same, or not?
>
>
>   set.seed(1)
>   a<- matrix(rnorm(9), 3 ,3)
>   sec.large<- as.vector(apply(a, 1, order, decreasing=T)[2,])
>   ans<- sapply(1:length(sec.large), function(i) a[i, sec.large[i]])
>   ans

Try

  apply(a, 1, function(x) sort(x, decreasing=TRUE)[2])

Peter Ehlers

>
> Thanks in advance for your help,
> Lars.
>
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>
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