I am using ArcGIS 10.2 for Desktop.

I have a model which contains several branches, which branch should run is based on the results of an earlier stage in the model. If the first stage of the model returns a Null result Branch A should run otherwise Branch B should run. I check for a Null result by using the Get Raster Properties tool ALLNODATA type.

At the start of each branch I created a Calculate Value tool which checks the Get Raster Properties and returns a 1 or 0 based on if that branch should run, and then uses the output as a precondition for the rest of the branch.

This sort of works but once the tool has been run once the various outputs are pre-set and instead of running the "Get Raster Properties" and "Calculate Value" tools again ModelBuilder jumps over to run the branches which meet their preconditions.

Is there a way to set all the results of Calculate Value to 0 before each run of the model so that branches are not run until the Calculate Value tool has run?

  • Can you upload a screen shot of the model as is?
    – Hornbydd
    Nov 25, 2015 at 15:57

1 Answer 1


I eventually solved this by writing a python script and importing it into the model.

# Import ArcPy module
import arcpy
# Define Parameters
checkB = arcpy.GetParameter(0)
checkDB = arcpy.GetParameter(1)
PosYes = arcpy.GetParameter(2)
PosNo = arcpy.GetParameter(3)
NegYes = arcpy.GetParameter(4)
NegNo = arcpy.GetParameter(5)
# Run Checks
if checkB == 1:
  PosYes = 0
  PosNo = 1
  PosYes = 1
  PosNo = 0
if checkDB == 1:
  NegYes = 0
  NegNo = 1
  NegYes = 1
  NegNo = 0
# Output Results

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