[R-sig-Geo] Focal function in R

[anusheema]

Yes! It worked. Thank you so much!

Best,
Anusheema.


On Mon, May 19, 2014 at 1:31 PM, Matteo Mattiuzzi [via R-sig-geo] <
ml-node+s2731867n7586468h78 at n2.nabble.com> wrote:

> Is that what you want?
>
> library(raster)
> # your reproducible! raster
> r <- raster()
> r[] <- sample(0:2,ncell(r),replace=TRUE)
>
> funX <- function(x){sum(x==1)}
> res1 <- focal(r,fun=funX,w=matrix(1, ncol=3, nrow=3))
> # or in this special case (sum if 1) also
> rn <- r==1
> res2 <- focal(rn,w=matrix(1, ncol=3, nrow=3))
>
> # more general (eg sum if 2):
> funX <- function(x){sum(x[x==2])}
> res3 <- focal(r,fun=funX,w=matrix(1, ncol=3, nrow=3))
>
> Matteo
>
>
> >>> anusheema <[hidden email]<http://user/SendEmail.jtp?type=node&node=7586468&i=0>>
> 05/18/14 8:57 PM >>>
> Hi!
>
> I want to run focal values for neighbourhood of focal cells using a
> matrix,
> with a function preferably. My data has 0, 1, and 2 as values, and I want
> to
> add values of "1" only, if I am using the focal function.
>
> It's probably a very simple question, and I have tried many combinations,
> but still not getting the desired results.
>
> Please help!
>
> Here's one of the codes that I was attempting:
>
> # to generate the function
>    my.function <- function (x) {
>       ux <- unique(x)
>       ux [if (x==1) ux <- focal(in_image, w=matrix(1/9, ncol=3, nrow=3)),
> fun=sum]
>       }
>
> # to run the focal window for the desired function
>     r_new <- focal(in_image, w=matrix(1/9, ncol=3, nrow=3),
> fun=my.function)
>
>
>
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-- 
Regards

*Anusheema Chakraborty*
Ph.D. Scholar
Department of Natural Resources, TERI University
10, Institutional Area, Vasant Kunj, New Delhi - 110070
Website: www.teriuniversity.ac.in




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