[STATSGRASS] rast.put & colors

[Roger Bivand]

On Mon, 16 Sep 2002, Bodo Ahrens wrote:

> 
> 
> > > hallo helpers,
> > >
> > > I try to use rast.put. I am able to put the raster file (floating
> > > precission with NA values) into grass.
> > >
> > > The problem is the color scheme: How can I define breaks and colors?
> > >
> > > I tried variations of
> > >
> > > rast.put(G,lname=paste("9",month.fname,day.fname,hour.fname,minute.fname,
> > >".",imgtype,sep=""), layer=aust$rimage.3d,
> > > title="2dRadarimage",breaks=c(-0.5,0.5,13.5),col=c("red","black"))
> > >
> > > but grass always applies its default colors.
> > >
> > > I am trying on
> > > LINUX SUSE 8.0
> > > GRASS/R 0.1-11
> > > R 1.5.1
> > > GRASS 5.0.0pre5
> > >
> > > What is the trick?
> >
> > I think you are getting caught in the conditions which are rather odd. If
> > aust$rimage.3d is a numeric vector (what does is.numeric(aust$rimage.3d)
> > say?) then I think you would get the behaviour you observe - I think you
> > would need to make aust$rimage.3d a factor first with cut(), using the
> > same breaks, then not give rast.put() the breaks. I certainly need to give
> > examples of how this is meant to happen on the help page, but at a
> > distance I'm not sure that this is the right explanation. Please let me
> > know if this helps or not, and I'll certainly upgrade the help page.
> >
> > Roger
> 
> Yes: is.numeric(aust$rimage.3d) is TRUE. It is a vector of integers (in my 
> test case) with values 0,1, ..13 and NA.
> 
> I tried
>   
> f<-cut(aust$rimage.3d,breaks=c(-0.5,0.5,13.5))
>   
> rast.put(G,lname=paste("9",month.fname,day.fname,hour.fname,minute.fname,".",imgtype,sep=""), 
> layer=f, title="2dRadarimage",col=c("red","black"))
> 
> and variations. No real change: grass applies standard color scheme. The 
> output of d.what.rast is now
> Buttons
>  Left:  what's here
>  Right: quit
> 
> -39077.99083333(E) 307902.65416667(N)
> 909262105.max in bodo, quant   (1)
> 909262105.max in bodo, actual  (1.000000)
> 
> 172364.2425(E) 226346.36416667(N)
> 909262105.max in bodo, quant   (2)
> 909262105.max in bodo, actual  (2.000000)
> 
> -276195.3525(E) 351701.4025(N)
> 909262105.max in bodo, quant   (Null)
> 909262105.max in bodo, actual  (Null)no data
> 
> for example. Obviously, I have imported now some "factors" (similar to 
> "categories" in grass?). Honestly, I have not understood the color (and 
> category) game in grass and actually want to import floatings. Is it possible 
> to import floatings with R/GRASS and it is when the only possibility to 
> generate an appropriate color table within grass?
> 
In the simplest case, when the layer is a numeric vector, and the 
quantization and colours are not important, then changing the colours 
within GRASS maybe a solution. I'll look at this - do you have a 
possibility to do save(G, aust, file="col.quant.ex.rda", compress=TRUE) 
and put the saved file somewhere I can download it to try out - is it very 
large? Could you create an example in a small region of your map for me to 
chew on - I think the main problem is documentation, which should be 
clearer.

Roger

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no
and: Department of Geography and Regional Development, University of
Gdansk, al. Mar. J. Pilsudskiego 46, PL-81 378 Gdynia, Poland.