[GRASS5] Re: d.vect.thematic wish: handle null values

[Michael Barton]

I'm not sure that nulls are the problem. It won't accept the <= operator.
Try straight > and < and see what happens. Also, what is FNR=1?

Michael
______________________________
Michael Barton, Professor of Anthropology
School of Human Evolution and Social Change
Arizona State University
Tempe, AZ  85287-2402
USA

voice: 480-965-6262; fax: 480-965-7671
www: http://www.public.asu.edu/~cmbarton


> From: Moritz Lennert <mlennert at club.worldonline.be>
> Reply-To: <mlennert at club.worldonline.be>
> Date: Thu, 11 Aug 2005 23:20:00 +0200 (CEST)
> To: Grass Developers List <grass5 at grass.itc.it>
> Cc: <michael.barton at asu.edu>, <dcalvelo at minag.gob.pe>
> Subject: d.vect.thematic wish: handle null values
> 
> Hi,
> 
> Trying to make maps with d.vect.thematic I have stumbled upon the problem that
> the module fails when there are null values in the table (postgresql):
> 
> **********
> awk: (FILENAME=- FNR=1) fatal: division by zero attempted
> 
> 
> Thematic map legend for column revmed of map ssbxl01
> 
> Value range:   -  33079
> Mapped by 7 intervals of
> 
> Color(R:G:B)    Value
> ============    ==========
> 0:0:250         7 -
> DBMI-Postgres driver error:
> Cannot select:
> SELECT cat FROM ssbxl01 WHERE revmed >= 7 and revmed<=
> ERREUR:  L'opérateur n'existe pas : integer <=
> HINT:  Aucun opérateur correspond au nom donné et aux types d'arguments. Vous
> devez ajouter des conversions explicites de type.
> 
> 
> 35:0:215                 -
> DBMI-Postgres driver error:
> Cannot select:
> SELECT cat FROM ssbxl01 WHERE revmed >  and revmed<=
> ERREUR:  syntax error sur ou près de «and» at character 41
> 
> etc...
> ************
> 
> Now I can see two theoretical solutions to this:
> 
> 1) handle null values
> 2) allow to give a value that represents null values (e.g. -99999)
> 
> For both of these solutions, d.vect.thematic should offer the choice of a
> color for these values, so that they do not use the same color scheme as the
> 'valid' values.
> 
> Moritz
>