topic Re: Need Help with Python Script in ArcGIS API for Python Questions

Need Help with Python Script

markheinrichs — Wed, 16 Jun 2021 15:48:39 GMT

In my attribute i have 2 columns i need to address. the layer is water valves and the 2 columns are valve size and exercised picture is attached. i need to reset my exercised column from yes back to null annually which i have the script for but i need to address the valve size 6",8",10",12" etc. individually so i can reset just that valve size. any ideas are appreciated.

thanks in advance

Re: Need Help with Python Script

DavidPike — Wed, 16 Jun 2021 16:13:52 GMT

I would just use a simple field calculation with python. either GP tool or right-click on the field in the attribute table and select calculate field. I would also make a copy/backup of your data before doing anything.

Calculate Field (Data Management)—ArcGIS Pro | Documentation

select Python as the language and then something like (NB you have aliases for your fields so use their real names in the below code):

if !valve_size! == '12"': return None

Re: Need Help with Python Script

DougGreen — Wed, 16 Jun 2021 17:15:53 GMT

So it sounds like you'd like to modify your python script to not only set the "Exercised" column back to NULL but also to do something with valve size. I can't exactly tell from your question what you need to do with the "Valve Size" column. Perhaps, you are wanting to just reset the "Exercised" column to NULL for valves of a certain size? If that is the case, I would use an update cursor with a where clause.

# set up an update cursor including any fields that you'll need updated or to determine what to update with arcpy.da.UpdateCursor(fcPath, field_names=['UNITID', 'VALVESZ', 'Exercised'], where_clause='VALVESZ IN (6, 8, 10)') as cursor: for valve in cursor: if (valve[2] != None): # None is python's equivalent of NULL valve[2] = None cursor.updateRow(valve)

Re: Need Help with Python Script

markheinrichs — Wed, 16 Jun 2021 18:18:52 GMT

i tried the line but i get the error in the attachment. i tried valve size without the underscore and no space same error.

thanks

Re: Need Help with Python Script

DavidPike — Wed, 16 Jun 2021 18:21:10 GMT

Can you perhaps check what the real field name is?

Re: Need Help with Python Script

markheinrichs — Wed, 16 Jun 2021 18:36:52 GMT

attached is a picture of the field names.

thanks

Re: Need Help with Python Script

markheinrichs — Wed, 16 Jun 2021 19:29:52 GMT

Thanks for the reply. i have 1774 different valves made up of 6 different sizes and we have to exercise them at different times to meet the state regs. i use python 3 script !Exercised!.replace("Yes","") to set everything that is yes back to null like it says and that works, but it is almost all the valves and i do want to pick the size and do just that size. the state wants 10" and 12" done every 2 years and anything smaller every 4 . i'm new to this and got lost in your answer but appreciate the quick response.

thanks

Re: Need Help with Python Script

DavidPike — Wed, 16 Jun 2021 22:55:00 GMT

No that's a picture of the attribute table with the field aliases.

Just find the fieldname in the expression window, then:

#enter this in the box below the '=' myFunction(!The name of your field as it appears in the fields window above!) #enter this in the 'code block' window def myFunction(size) if size == '12"': return None