Is it possible to configure SA in a Python script?

Question

Dear all,

I have to perform map algebra operations on rasters that have different extents, and I want to obtain an output on the union of the extents. I am doing this in a Python script; is there a way to configure Spatial Analyst output extent to "Union of Inputs" by calling a geoprocessor method from my script?

Thank you and best regards,

Cedric

ArcGIS Desktop 9.3.1, ArcInfo license.

curtvprice · Answer

Here's the 10.x flavor of this:

import arcpy
from arcpy.sa import *
arcpy.env.workspace = r"C:\Workspace"
arcpy.env.extent = "MAXOF"
outRaster =  Raster(r"C:\data\rasterA") + Raster(r"C:\data\rasterB" )
outRaster.save("outRaster")

Output Extent (Environment setting)—Help | ArcGIS for Desktop

RyanDeBruyn · Answer

You may need to review the environement settings for extent.

http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=2237&pid=2229&topicname=Output_extent

also for Map Algebra in 9.3
http://webhelp.esri.com/arcgisdesktop/9.3/index.cfm?id=6311&pid=6308&topicname=Single_Output_Map_Algebra

for example:

gp = arcgisscripting.create(9.3)
gp.workspace = "C:/workspace"
gp.Extent = "MAXOF"
inExpresson = "C:\data\rasterA + C:\data\rasterB"
gp.SingleOutPutMapalgebra_sa(inExpression,"outRaster")

Good luck
Ryan

DanPatterson_Retired · Answer

Sorry Cedric, don't have a 9.3.x installation here, acrpy does open up a whole new world which didn't exist in previous versions.