Perform raster calculation using ArcPy

Summary

The Spatial Analyst tools can be executed using the Spatial Analyst ArcPy module to perform raster analysis. When writing a Python script, it is possible to drag and drop a tool into the Python console to generate a line of code. Although the line of code is generated for the Raster Calculator tool, the execution returns an empty output, or fails with the following error message:

Error:   
AttributeError: module 'arcpy.sa' has no attribute 'RasterCalculator' 

Procedure

The sample script below represents the workflow to modify pixel values using the multiplication operation on all the rasters in a folder.

1. Import the necessary module.

import arcpy
from arcpy import env
from arcpy.sa import *

2. Specify the desired workspace.

arcpy.env.workspace = r"<location_path>\<name>.gdb"

arcpy.env.scratchWorkspace = r"<location_path>\<name>.gdb"

3. Print the list of available raster files in the folder.

raster_list = arcpy.ListRasters("*")
print (raster_list)

4. Check out the Spatial Analyst extension.

try:
    if arcpy.CheckExtension("Spatial") == "Available":
        arcpy.CheckOutExtension("Spatial")
        print ("Checked out \"Spatial\" Extension")
    else:
        raise LicenseError
except LicenseError:
    print "Spatial Analyst license is unavailable"
except:
    print arcpy.GetMessages(2)

5. Loop through all the raster files, perform the calculation, and specify the desired save folder.

for raster in raster_list:
    ras = Raster(raster)
    filename = str(raster)[:-3] + '<desired file extension>'
    outraster = ras * <desired_value>          
    outraster.save(r"<location_path>\<name>.gdb" + "\\" + filename)