Set the NA value of a RasterLayer
NAvalue.RdNAvalue returns the value that is used to write NA values to disk (in 'raster' type files). If you set the NA value of a Raster* object, this value will be interpreted as NA when reading the values from a file. Values already in memory will not be affected.
If the NA value is smaller than zero, all values smaller or equal to that number will be set to NA.
Examples
r1 <- raster(system.file("external/rlogo.grd", package="raster"))
r2 <- r1
NAvalue(r2)
#> [1] -3.4e+38
NAvalue(r2) <- 255
#plot(r1)
#x11()
#plot(r2)