Reclass null values in text field using Calculate Field

Question

I have a text field called 'Description' that contains some values that I wish to update to 'Hedgerows' while keeping all other values the same. Using Calculate Field in Pro, I tried the following: Expression: Reclass (!Description!) Code block def Reclass(Description): if (IsNull) return Hedgerows The expression was successfully verified but I then got the following error message when running the tool: Error 00539: Error running expression: Reclass (u"Buildings") Traceback (most recent call last): File "", line 1, in File ", line 2, in Reclass Name Error: name 'IsNull' is not defined Failed to execute (CalculateField). Any suggestions? I'm a complete novice when it comes to Python.

DataOfficer · Answer

Thanks - this is the example I tried to follow but wasn't sure how to handle 'Null' values (in a string or numeric field). I think I'm beginning to get a better sense of it. What I would really like to see is a feature class version of the 'Reclassify' tool so users that aren't familiar with Python can easily define 'Start' and 'End' values without using code.

Anyway, thanks for the help!

KoryKramer · Answer

Since you're a novice to python, I just wanted to make sure you were aware of the Helpers in Pro:

Adding your story about Reclass on this idea ArcGIS Pro Field Calculate Helpers‌ would be worthwhile.

The reclass example is in the doc: Calculate Field examples—Data Management toolbox | ArcGIS Desktop  (Ctrl+F 'reclass')

That doc on examples might be helpful to you in the future as well.

Cheers

TedKowal · Answer

Lot of ways to appoach it ... one way is to make the number a string... but the test doesnt care whether or not the variable is a number or string so testing myNumber is None would be valid as well -- It is what you return to the field that is important. def reclass (myNumber): if str(myNumber) is None: return 911 return myNumber reclass(!NumberField!)