Dear Chris,
If 'x' is your matrix, you could try this:

tail(sort(apply(x,1,max)),2)

HTH,

Jorge


On Sat, Sep 20, 2008 at 8:48 PM, Chris82 <rubenbauar@gmx.de> wrote:

>
> Hello R users,
>
> is there a possibility to get the relativ maximum of a matrix?
> To get the absolut maximum I use max(matrix)
>
> For example:
>
> The absolut maximum of this matrix is 6[3,6], but the relativ maximum is
> 6[3,6] and 4[7,6], because both values are the highest value in comparison
> to their eight neighbours values.
>
>     [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8]
> [1,]    1    1    2    2    2    1    1    2
> [2,]    1    2    3    3    3    4    4    3
> [3,]    3    3    3    4    4    6    5    4
> [4,]    4    4    4    3    3    4    4    3
> [5,]    3    4    4    3    3    3    2    2
> [6,]    3    3    3    3    3    3    2    2
> [7,]    2    2    2    2    2    4    2    1
> [8,]    1    1    0    0    0    0    0    0
>
> my first idea was to use this code:
>
> a <- matrix
>
> for (i in 2:7){
>  for (j in 2:7){
> relmax <- a[a[i,j] > a[(i-1),(j-1)], a[(i-1),j], a[(i-1),(j+1)],
> a[i,(j-1)],
> a[i,(j+1)], a[(i+1),(j-1)], a[(i+1),j], a[(i+1),(j-1)]]
>  }
> }
>
> but the code doesn't really work
>
> thanks.
>
> greets
> --
> View this message in context:
> http://www.nabble.com/Searching-a-relativ-maximum-of-a-matrix-tp19590576p19590576.html
> Sent from the R help mailing list archive at Nabble.com.
>
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