Thematic mapping in MapServer

[Stephen Lime]

Not sure if I understand what you're after completely but I'll give it a shot. How you handle it sort of depends on the data your mapping and what sort of an interface you want to have. If all the index columns can be classified the same way, for example in to 3 classes of low, medium and high, then you could probably get away with one layer definition and just change the classitem on-the-fly depending on which variable the user wants to see. If the variables have radically different classifications then you almost have to define multiple versions of the shapefile (i.e. different layers). I did some stuff early on with forest polygons and different thematic maps (age, density, species, etc.) and used multiple defs of the same shapefile to produce the maps. Instead of redefining the same query over and over I defined a layer based on the same shapefile but set its status to QUERYONLY so that all queries against any of the thematic maps actually hit that layer and any individual thematic map were not itself queryable. Perhaps Ken Boss can share one of the  forestview mapfiles. If your data are all percentages or something like that and you can get away with a common classification (i.e. set of CLASS definitions) then the on-the-fly changing of CLASSITEM might just be the ticket. Only version 3.3 supports mapfile parameter changes via a form or url.

Hope this helps.

Steve

<<< Ma <marin at here.is>  1/ 7  7:52p >>>
Dear All,

What is the best way to make more than one thematic mapping for one and
the same SHP file and what about the queering in this case? Ideas,
solutions, URL, map file?

For example I have data like this:

Country      Index-1   Index-2   Index-3  Index-...
------------------------------------------------------
Canada         0        32        54
Peru          25         0        19
Romania       78        80         0
Australia      0        10        65
UK            14        56        44
Germany       96         0        12
USA           74        21        12
Italy          0        89         0

How to make thematic mapping for all these columns in MapServer? And if
you have 50 columns or more ... ? If you add the SHP file 50 times in
the map file - what about the queering after?? Help!

--
Ma