Faster way to check if a SpatRaster has at least one non-NA value

[kevinwolz]

To check if a SpatRaster (x) has at least one non-NA value, I am currently using this:

any(as.numeric(terra::global(x, fun = "notNA")[,1]) > 0)

This works on SpatRasters that have one or multiple layers. It works fine, but I think terra::global is checking the entire raster. I don't need to check the entire raster, and, for large rasters, this can take a long time. I'm looking for a method that stops when it finds the first non-NA value. This would save considerable time when checking a large SpatRaster.

Would it be possible to implement something like fun = "anynotNA" for terra::global?

For context, the reason I am doing this check in the first place is because I am using terra::trim() in a situation where the raster may or may not have non-NA values. When applying terra::trim() to a SpatRaster with only NA values, it throws an error, so I must check to ensure there is at least one non-NA value before applying terra::trim(). Perhaps there is a better way to deal with this in this specific example? Either way, I think this feature would be useful in other contexts as well.

[rhijmans]

I have added functions "anyNA", "anynotNA" that ought to be more efficient.