Why do the rules I defined using the MAKESYMBOLSPEC command seem to be ignored?

It sometimes happens that polygons from the same shape file will overlap each other. If this happens, it may seem that a rule is not being applied correctly.

Answer 1

[MathWorks Support Team]

GEOSHOW makes no promises about the order in which it constructs the polygons in the geostruct s, and it turns out to be a little bit easier, from an implementation perspective, to order them from last to first. Normally that causes no problems -- typically one is displaying polygons that either tile to cover a space (e.g., the 48 conterminous U.S. states) or that are otherwise non-overlapping (e.g., the polygons in landareas.shp).

You can work around this issue by changing the order of the geo-struct input to the GEOSHOW command.

s = shaperead('your_data_file_here');

% just as an example

clrs=makesymbolspec('Polygon', {'LevelString','land','FaceColor',[0 .8 0]},...

{'LevelString','lake','FaceColor',[0 .8 1]},...

{'LevelString','pond','FaceColor',[0 .8 1]},...

   {'Default','FaceColor','k'});

% note the changed input order to GEOSHOW

geoshow(s(end:-1:1),'symbolspec',clrs);