On Thu, Sep 17, 2015 at 11:56 AM, Moritz Lennert < [email protected]> wrote:
> On 16/09/15 10:48, Paulo van Breugel wrote: > >> >> >> On 16-09-15 09:49, Moritz Lennert wrote: >> >>> On 15/09/15 20:08, Paulo van Breugel wrote: >>> >>>> Suppose I have a categorical raster map and I want to 'cut out' a subset >>>> (with g.region to set a small region and r.mapcalc to create the new >>>> map). This map has a smaller number of categories, as is shown using >>>> e.g., r.category. However, when plotting the legend, all the categories >>>> of the original map are included in the legend. Checking the 'cats' file >>>> shows that it indeed lists all original categories and labels, including >>>> for those categories not present in the new map. This doesn't make sense >>>> to me, but perhaps I am missing something here? >>>> >>> >>> AFAIK, the legend is determined by the color table, and the color >>> table is probably just copied as is from the input to the output map. >>> You can check with r.colors.out. If you redefine a color table with >>> only the relevant categories, then the legend should reflect that. >>> >> >> Hi Moritz, that is what I thought, and as the whole color table does >> indeed get copied over, I wrote a small script to remove the 'redundant >> color definitions. However, that did not help, the whole 'old' legend is >> still showing. I had missed that -n flag, so I'll give that a try. Is >> there a similar option in ps.map to omit categories without label? >> >> From a more conceptual point of view, is there any reason the whole >> category table is copied over to the new cats file? >> > > Probably not. IIUC, this only happens when you have a formula of the form > "new = old". > > An easy work around: > > r.category new | r.category new rules=- > > The resulting cats file only contains the cats actually present and you > can thus use d.legend -n to only show those. > That is a very neat trick, thanks! > > Moritz > > >
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