Wishing we had COLORRAMPs or something

[Stephen Woodbridge]

Bill,

Hey, this sounds great!
I will give it a try. I knew you had done some work in this area, but I 
did not realize it was in 4.6 which I am using.

What I just got working on my laptop, using postGIS and some perl code 
is an app that lets me select any of large number (200+) demographic 
variable and a state, then it queries the data from postgres and applies 
one 4 different classification schemes to the data to generate breaks 
and then requests a map and the zcta polygons are classified by 
converting the attribute value into a 0 .. N class number and the 
mapfile has classes to color it. I need to generate a legend to also but 
probably need to do it outside of mapserver because I have already 
reduced the classification to 0 .. N classes. Your ramp is just what the 
I need because I can pass the numclasses as %numclasses% to the ramp.

At some point in the near future I will move the database back over to 
the server then I can post a demo link.

Very Cool!
   -Steve

Bill Binko wrote:
>>Why is this needed? you ask, just make a bunch of classes.
> 
> 
> Mwuu ha ha  (*seang will kill me for this*) 
> 
> Take a look at bug 1305, and see if that will fit your needs.
> 
> It is close, but not exactly what you want.  Most obviously, legend 
> support is non-existant at this point, but I could be motivated to help 
> there if I ever get away from ECW and GeomUnion issues.
> 
> If you're running 4.6, then support is already in there for you. 
> 
> 
>>For a thematic map, you can select the number of breaks you want to 
>>display, between 2 and 10 say. I already have code to compute the class 
>>breaks and to assign them a number between 0 and numclasses, now I need 
>>to a color in the ramp based on numclasses. If your ramp is RED from 0 
>>to 255, and you have a 2 class ramp the 2 will be 255, but if you 
>>display the same thin with a 10 class ramp 10 will be 255 and 2 will be 
>>like 25.5
>>
> 
> 
> In this case, you'd want to do something like this:
> 
> 	CLASS 
> 		COLOR 0 0 0 #mapserver wants a default color 
> 		STYLE
> 			COLORRANGE 0 0 0 255 0 0 #start and end colors
> 			DATARANGE 0 10 #start and end values
> 			RANGEITEM "someField" #the field to use
> 		END
> 	END
> 
> No doubt this is not perfect (it has no "breaks": it is continuous).  
> However, having another user try it and provide feedback (into the bug 
> please) can only help.
> 
> Bill
>