[mapserver-users] Expression statement (FWD)

[teb]

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X-Sender: geo402 at mailms.abdn.ac.uk
Date: Mon, 14 Jan 2002 16:58:06 +0000
To: mapserver-info at lists.gis.umn.edu
From: "Stephen D. King" <s.d.king at abdn.ac.uk>
Subject: Expression statement
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Hi,

I am trying to get mapserver to display classes from one shapefile - 
without success - I just get a blank image. I can get it to display the 
shapefile without the class divisions.

The shapefile is called Gr_nhs.shp

It is divided up into 23 classes. Each class takes its value from the 
Grid_code attribute field. -9999 is unknown, the remaining values are from 
1-22

In my map file, the layer definition is as follows:

LAYER
	NAME Gr_nhs
	TYPE POLYGON
	STATUS DEFAULT
	DATA Gr_nhs
	CLASSITEM "Grid_code"

CLASS
	Name "Unknown"
	EXPRESSION ([Grid_code] eq -9999)
	COLOR 210 275 25
END
END
END # Map file


I have tried various combinations for the expression - can anyone help?

Thanks,

Stephen


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