topic Re: Python if statement in arcpy.CalculateField_management isn't working? in Geoprocessing Questions

Python if statement in arcpy.CalculateField_management isn't working?

MichaelRamm — Mon, 12 Dec 2016 17:29:09 GMT

Hi - I'm having trouble getting an if statement to work and was hoping someone could help?

I need to copy the data from a field called SUM_Green to G, replace any null values in a dataset with 0, so I've used the following, but can't seem to find anything that works:

Any ideas?

Thanks.

Re: Python if statement in arcpy.CalculateField_management isn't working?

DarrenWiens2 — Mon, 12 Dec 2016 18:17:02 GMT

Just slightly different syntax:

arcpy.CalculateField_management(MULTIs, "G", "!SUM_Green! if !SUM_Green! >= 1 else 0", "PYTHON_9.3","")‍‍‍

Re: Python if statement in arcpy.CalculateField_management isn't working?

JoshuaBixby — Tue, 13 Dec 2016 01:42:43 GMT

I agree with Darren Wiens‌ that using Python Conditional Expressions is the way to go in situations like this. In case you couldn't rely on SUM_Green being greater than or equal to one, you can explicitly handle NULL by using Python's NoneType:

arcpy.CalculateField_management(MULTIs, "G", "0 if !SUM_Green! is None else !SUM_Green!", "PYTHON_9.3","")‍

Re: Python if statement in arcpy.CalculateField_management isn't working?

MichaelRamm — Tue, 13 Dec 2016 11:13:00 GMT

Thanks for both your responses, I've tried Joshua's suggestion and the script has ran through perfectly, just what I needed. Cheers.