Dear Joelle, 1. Please use isundef function. This seems to work better than traditional Ilwis command you are using, specially for the value domain map. So please change your statement like this.
sigma_parcelles:= IFF(isundef(parcellesnr),?,14oct02cal) 2. For the mean value: You can use histogram value of raster map to group by in table calculation. Regards Bishwa Pandey Tel: 0058-212-9855726 Mobile:0058-414-1244345 Member - JICA Study Team Basic Plan for the Prevention and Attention of disaster for the Metropolitan Area of Caracas -----Mensaje original----- De: Joelle Dagnelies [mailto:[EMAIL PROTECTED] Enviado el: Jueves, 25 de Septiembre de 2003 10:10 a.m. Para: [EMAIL PROTECTED] Asunto: (ilwis-list) iff Dear list members, I have a polygon map showing the borders of 82 fields : parcellesnr. I want to extract from a radar map the values located in these fields . For this, I rasterized the parcellesnr map (id domain changed to value domain) and I tried the following statement (based on the message "study area" from march 12, 2003 on the list) sigma_parcelles = IFF(parcellesnr, 14oct02cal, ?) I receive an error message :'operator' expected, Ilwis error 4020 Can somebody tell me what is wrong ? I tried to change the domain of parcellesnr from ID to value, changed the statement, ...always receiving an error message (sometimes invalid 'operand') Another question : once I have the 82 fields with their radar values, how can I calculate, easily, the mean values for each field ? Thank you, Joelle _________________________________________________________________ Hotmail: votre e-mail gratuit ! http://www.fr.msn.be/hotmail ____________________________________________________________ Free 20MB Web Site Hosting and Personalized E-mail Service! Get It Now At Doteasy.com http://www.doteasy.com/et/ ________________________________________________________ To leave the ILWIS-LIST discussion list, send a email with 'unsubscribe ilwis-list' in the body to '[EMAIL PROTECTED]'
