arcpy raster calculation wrong result

Question

I want to use arcpy raster calculation to create some script but the output raster to get from this arcpy raster calculation script is different from this to take from model builder in ArcGIS gui,any idea why ?

arcpy script :

con='("{0}"*"{1}"*"{2}")'.format(raster1,raster2,raster3)
arcpy.gp.RasterCalculator_sa(con, rstercalc)

raster calculation in model builder :

my raster is float if I try to use float(raster1) I take error :

float cannot convert in memory layer

I have some wrong in con in script or the wrong is the in_memory layer where I use ?

Answer 1

The Raster Calculator help page says:

The Raster Calculator tool is intended for use in the application only as a GP tool dialog box or in ModelBuilder. It is not intended for use in scripting.

You could use the Con tool if you want to calculate a conditional value (as your variable name implies).

If you just want to multiply 3 rasters, Times is more appropriate. See the code samples at the bottom of the page to fix your code. You will need to run Times twice (first raster1 * raster2, then result * raster3).

Times is the geoprocessing/scripting equivalent of the Map Algebra * operator.

Answer 2

In your example image, you do not even have a con statement. It is a straight multiplication.... if you need to turn this into a Con statement, this will give you a backbone to work with as well... try:

import arcpy, os
from arcpy.sa import *
arcpy.CheckOutExtension("spatial")

raster1 = r'c:\temp\ras1'
raster2 = r'c:\temp\ras2'
raster3 = r'c:\temp\ras3'
arcpy.env.workspace = r'c:\temp'

raster = Raster(raster1) * Raster(raster2) * Raster(raster3)
raster.save('new_raster')