[R] Searching a relativ maximum of a matrix
Chris82
rubenbauar at gmx.de
Sun Sep 21 02:48:03 CEST 2008
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
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