[R-sig-Geo] gdal color tables

[Barry Rowlingson]

On Thu, Jan 3, 2013 at 7:06 PM, Agustin Lobo <alobolistas at gmail.com> wrote:
> Happy 2013 to everyone!
> Thanks Barry, very useful page.
> Nevertheless, I think the equivalent to zlim in plot() should be
> included also, because most of the time
> we use standard palettes that must be applied to the particular range
> of interest of the raster(s) (note
> real raster data often has outliers), i.e.:
> plot(r,col=matlab.like(64),zlim=c(20,50))

 My only concern here was with categorical rasters, where the values
(and hence the colours) are only meaningful with a label. For example
20=Deciduous Forest, 21=PIne Forest, 22=Burnt Forest, 10=Meadow,
12=Urban, and so on. In this context I don't see a need to restrict
plotting with zlim because the idea of 'limits' for a non-continuous
variable is a bit odd. You might want to get all the forest-related
variables and so plot everything from 20 to 29, but if your interest
is forestry then you should probably select those categories from the
raster into a new raster.

My intention wasn't to create a generic value-colour palette handling system.

I've also written some code that works with legend to display legends
for categorical data. I don't really want to release it until the
raster package decides what RasterLegend objects are all about...

Barry