R Focal Function - Terra vs Raster

Question

I'm not sure why the focal function I've been using in Raster does not work with Terra. This simplified example uses a custom function to apply the focal filter only to pixels with a value of 0 and it "grows" the pixels out to neighboring pixels (rooks case)....It works with raster, but I get the following message when attempting in Terra: Error: [Focal] test failed

library(raster)
tmpRas = raster(matrix(c(1:14,0,16:36,6,6))
plot(tmpRas)

grow0 = function(x){if (0%in%x){return(0)} else {return(x[5])}
w=matrix(c(NA,1,NA,1,1,1,NA,1,NA),3,3)
FocalRas = focal(tmpRas, w, fun = grow0, pad=TRUE, padValue = 1)
plot(FocalRas)

Any ideas on why this same method does not work with Terra, or is there an easier way to do what I'm trying to accomplish? Here is the same workflow using Terra:

library(terra)
tmpRast = rast(matrix(c(1:14,0,16:36),6,6)
FocalRast = focal(tmpRast, w, fun = grow0)

Answer 1

The example worked for me using:

library(terra)

tmpRast = rast(matrix(c(1:14,0,16:36),6,6)) # terra spatRaster object

grow0 = function(x){if (0%in%x){return(0)} else {return(x[5])}}
w=matrix(c(NA,1,NA,1,1,1,NA,1,NA),3,3)

FocalRast = terra::focal(tmpRast, w, fun = grow0) # terra::focal
plot(FocalRast)

It was only necessary to fix some minor bugs in the code. I also added terra::focal so that I used the function from the terra package. I'm not sure, but it's probably more efficient than raster::focal.

If it still doesn't work for you update your terra package to:

terra version 1.4.11