topic Re: Calculate Field to update a column based on not null in another column in Python Questions

Calculate Field to update a column based on not null in another column

deleted-user-1sAsOmMajBua — Tue, 22 Jan 2019 02:22:07 GMT

(i"m new to arcpy and arcgispro)

I'm attempting to use the Calculate Field to update a column based on non-null values in another column:

Expression:
UpdateLoc(!GAZETTED_LOCALITY_NAME!)

Code Block:
def UpdateLoc(nameGaz):
if (nameGaz != none):
return 'L'

(I've tried != NULL and IS NOT NULL as well)

I'm not sure where I am going wrong here, I get '2 parameters are missing or invalid'

JoshuaBixby — Tue, 22 Jan 2019 02:55:11 GMT

For this type of basic conditional check, you don't need a code block. Set the parser to Python and try the following expression:

'L' if !GAZETTED_LOCALITY_NAME! is not None else None‍‍‍

NULL in databases and data stores gets mapped to Python None.

DanPatterson_Retired — Sun, 12 Dec 2021 04:58:48 GMT

and if you want to use your code block, you don't include the …. Expression : nor the Code block lines,

Underneath Type (which is the field you are trying to calculate values for, you put the expression in there

Type:

----------------------------------

UpdateLoc(!GAZETTED_LOCALITY_NAME!)

Then in the code block section

Code Block

----------------------------

def UpdateLoc(nameGaz):
    if nameGaz is not None:
        return 'L'‍‍‍
    return None‍‍‍‍

code blocks and expression lines take a bit of getting used to.

If you reuse and expression a lot, you can save them a *.cal files, and then reload them

deleted-user-1sAsOmMajBua — Tue, 22 Jan 2019 03:39:14 GMT

Thanks for that - it wasn't clear what went in what box from the example I ripped off (Calculate Field Python examples—Data Management toolbox | ArcGIS Desktop ).