R help - Mar 2012 - Finding the maximum elements in an array/matrix

Hello,

   I would like to find the maximum element in a matrix or an array but it
does not return what I want.

   For example, If I have a 2*2 matrix A whose maximum element is the
A(1,2). I would like the answer (1,2), but it returns 3, which is the
ordinal if one counts by columns. Is there any function that returns (1,2)?


   Thanks
> A<-rbind(c(1,4), c(3,2))> A     [,1] [,2]
[1,]    1    4
[2,]    3    2> which.max(A)[1] 3

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As they say, RTFM....in particular, this part:

? which.max --> See Also:

     Use ?arrayInd()?, if you need array/matrix indices instead of 1D
     vector ones.

Michael

On Thu, Mar 29, 2012 at 10:27 PM, jpm miao <miaojpm at gmail.com>
wrote:
> Hello,
>
> ? I would like to find the maximum element in a matrix or an array but it
> does not return what I want.
>
> ? For example, If I have a 2*2 matrix A whose maximum element is the
> A(1,2). I would like the answer (1,2), but it returns 3, which is the
> ordinal if one counts by columns. Is there any function that returns (1,2)?
>
>
> ? Thanks
>
>> A<-rbind(c(1,4), c(3,2))> A ? ? [,1] [,2]
> [1,] ? ?1 ? ?4
> [2,] ? ?3 ? ?2> which.max(A)[1] 3
>
> ? ? ? ?[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org mailing list
> 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.

Try

which(A == max(A), arr.ind = TRUE)

HTH,
Jorge.-


On Thu, Mar 29, 2012 at 10:27 PM, jpm miao <> wrote:
> Hello,
>
>   I would like to find the maximum element in a matrix or an array but it
> does not return what I want.
>
>   For example, If I have a 2*2 matrix A whose maximum element is the
> A(1,2). I would like the answer (1,2), but it returns 3, which is the
> ordinal if one counts by columns. Is there any function that returns (1,2)?
>
>
>   Thanks
>
> > A<-rbind(c(1,4), c(3,2))> A     [,1] [,2]
> [1,]    1    4
> [2,]    3    2> which.max(A)[1] 3
>
>        [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help@r-project.org mailing list
> 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.
>
	[[alternative HTML version deleted]]