I try to find a circular filter that I can export to be used in a spatial software.
Assuming, we have a matrix, representing 9x9 regularly spaced points with the center point 'filter[5, 5]'. In this example, I want to find a function that weighs all neighbor points within a distance of d=4 units with 1:
> filter <- matrix(0, 9, 9) > filter <- function() ... > filter [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [1,] 0 0 0 0 1 0 0 0 0 [2,] 0 0 1 1 1 1 1 0 0 [3,] 0 1 1 1 1 1 1 1 0 [4,] 0 1 1 1 1 1 1 1 0 [5,] 1 1 1 1 1 1 1 1 1 [6,] 0 1 1 1 1 1 1 1 0 [7,] 0 1 1 1 1 1 1 1 0 [8,] 0 0 1 1 1 1 1 0 0 [9,] 0 0 0 0 1 0 0 0 0
Finally, I want to use a larger matrix, e.g. with 61x61 points. Is there a simple function around that I could use to this end?
I don't know whether there is a function makeYourFilter(), but I'm pretty sure it's easy to write it. Unfortunately, I don't know which distance you are talking about.
Uwe Ligges
Thanks! Christof
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