Re: [R] Second largest element from each matrix row

From: Peter Ehlers <ehlers_at_ucalgary.ca>
Date: Tue, 26 Apr 2011 05:31:07 -0700

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.
>
> [[alternative HTML version deleted]]
>
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https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code. Received on Tue 26 Apr 2011 - 12:33:14 GMT

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