Hamish: >> "the way to do this is to use >> r.category to add category labels to each of your four >> raster category numbers, then use d.legends's -c flag to >> hide the value of the number, so only the label is >> displayed."
Martin Album Ytre-Eide wrote: > This was exactly what I was looking for. This solves many > of my legend issues. Thanks a lot. glad to hear it. > A follow up question is: Would this be a good way to deal > with logarithmic values in a legend? d.legend use=, but the version from GRASS 6.5 or 7, with Dylan's verbatim patch. > -I convert rasters to have logarithmic values with > r.mapcal: map = log(old_map,10) > -This gives me a nice map with a nice legend. One could use > r.colors -g (logarithmic scaling), but this messes up the > legend - the legend is still linear- and it does not look > good. > -The problem is(my way of doing things) that the category > numbers are log values as well(say 1-3-5 insted of > 10-1000-100000), which there is noting wrong with, it is > just not that easy to read. use= will draw at whatever levels you give it; I plan to backport the (anti-)rounding patch for 6.4.2, ie after some time of live testing. see https://trac.osgeo.org/grass/ticket/1147 feedback welcome. > So, is it a good idea to add category labels to all values > (or a range of values) x - 10^x ( so for 1, I add 10 and so > fort) or is it a better way to do this as well? It's a matter of taste, but personally I am not a fan of band rendering- where you (as a human) decide to arbitrarily assign the category breaks can have a most remarkable(!) effect on how the map is interpreted by other humans. See "how to lie with statistics", "how to lie with maps", and other related books & articles. You'll probably be most convinced by your own data one day, when you pop one of your own insights after a new rendering. In nature such thresholds are not so clearly defined. To aid the viewer of a figure my favourite method is a continuous color gradation + overlaid contour lines. but anyway, ... the easiest way to display classes from raster data in GRASS is to make a r.colors rule set like: 0% blue 25% blue 25% cyan 50% cyan 50% yellow 75% yellow 75% red 100% red then r.category 'a - b' classes + d.legend use= can work. hint for the above: remember that if you are careful the map displayed and the legend displayed can actually be for two different maps (one of which being a dummy which just exists for making the legend). (note to self- verify that GRASS 7 doesn't optimize that step functionality away) I think Arc & copycats use class breaks so much in their legends simply as a matter of the vector-feature heritage of that software; histogram classes make more sense if you start with a number of sparse data points. In raster maps (traditionally GRASS's strong point) it is more a case of continuous gradations. shrug; just a small theory. hope it helps, Hamish _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user