Raster Calculator Python

Question

Hi Everyone, I am trying to implement a simple raster calculator within my python script as the following arcpy.gp.RasterCalculator_sa(""%Temp4%"/2", Temp2) But I am receiving the following error in python "Warning (from warnings module): File "", line 1 SyntaxWarning: import * only allowed at module level Traceback (most recent call last): File "F: est.py", line 75, in arcpy.gp.RasterCalculator_sa(""%Temp4%"/2", Temp2) File "C:\Program Files (x86)\ArcGIS\Desktop10.0\arcpy\arcpy\geoprocessing\_base.py", line 474, in return lambda *args: val(*gp_fixargs(args)) ExecuteError: ERROR 000539: Error running expression: rcexec() : unsupported operand type(s) for /: 'str' and 'int' Failed to execute (RasterCalculator)." I am using arcpy.CheckOutExtension("spatial") so im not sure what the first point of the error is implying! This is really frustrating... any help would be appreciated! Bjebn

RaphaelR · Answer

try removing the ' before and after RasterImage in the Temp4 = FocalStatistics()... line. It´s a variable, i think they way you´ve got it in  there it´s looking for a string

JohanL · Answer

I am still having problems with map algebra... its probably an obvious mistake but I cant identify it! Here is a part of the code im having trouble with... import arcpy, os, sys, string from arcpy import env from arcpy.sa import * arcpy.CheckOutExtension("spatial") arcpy.env.workspace = r'O:\DATA est' InputFolder = arcpy.env.workspace Temp4 = InputFolder + '\' + temp4 RasterList = arcpy.ListRasters() for RasterImage in RasterList: Temp4 = FocalStatistics('RasterImage', NbrRectangle (9, 9, 'CELL'), "RANGE", "DATA") print ('Focal Statistics') ..... I receive the following error "Traceback (most recent call last): File "O: est.py", line 67, in Temp4 = FocalStatistics('RasterImage', NbrRectangle (9, 9, 'CELL'), "RANGE", "DATA") File "C:\Program Files (x86)\ArcGIS\Desktop10.0\arcpy\arcpy\sa\Functions.py", line 4796, in FocalStatistics ignore_nodata) File "C:\Program Files (x86)\ArcGIS\Desktop10.0\arcpy\arcpy\sa\Utils.py", line 47, in swapper result = wrapper(*args, **kwargs) File "C:\Program Files (x86)\ArcGIS\Desktop10.0\arcpy\arcpy\sa\Functions.py", line 4790, in wrapper ignore_nodata) File "C:\Program Files (x86)\ArcGIS\Desktop10.0\arcpy\arcpy\geoprocessing\_base.py", line 474, in return lambda *args: val(*gp_fixargs(args)) ExecuteError: Failed to execute. Parameters are not valid. ERROR 000865: Input raster: RasterImage does not exist.Failed to execute (FocalStatistics)." It does not seem to recognize my for in loop of the RasterImage - any ideas?

JohanL · Answer

according to the help, the raster calculator is for use inside arcmap only, for calculations in python you should use mapalgebra:
http://help.arcgis.com/en/arcgisdesktop/10.0/help/index.html#//009z000000z7000000.htm

Ah of course... i did the mistake of exporting the script from the modelbuilder and tried to modify it -  what a frustrating mistake!