Using Conditional Statements to add from different fields in Field Calculator (Python)

[JoshBillings]

Hey all,

I am new to Python. I am currently trying to write a calculation using Python in the field calculator ONLY IF another field equals a specific value.

For instance, I have a MAINTENANCECOMPLETE field, a MAINTENANCETYPE field, a DEFMAINTENANCE field, and a COST field.

I want the MAINTENANCECOMPLETE field to populate the sum of DEFMAINTENANCE and COST only if MAINTENANCETYPE is equal to "DM General."

Here is what I currently have:

Code Block:

def ifBlock(maintenanceType):
     if maintenanceType== 'DM General'
          return !DEFMAINTENANCE! - !Cost!

Actual Code:

ifBlock(!MaintenanceType!)

How should I write this differently?

Let me know if I can clarify in any way.

[JoshuaBixby · Accepted solution]

You don't have to use the code block for this, you can use Python conditional expression, a.k.a, ternary operator:  6. Expressions — Python 3.9.2 documentation

Expression:

!DEFMAINTENANCE! + !COST! if !MAINTENANCETYPE! == 'DM General' else !MAINTENANCECOMPLETE!

[JoshBillings]

Genius. Thank you. I was making it more difficult than I should have.

What if I had several attributes for MAINTENANCETYPE?

When I try to use this below, it populates all fields with the difference of DEFMAINTENANCE - COST even if it doesn't meet the criteria:

!DEFMAINTENANCE! - !COST! if !MAINTENANCETYPE! == 'DM General' or 'DM Asset Protection' or 'DM Priority Safety Concern' else !MAINTENANCECOMPLETE!

Any way to do this @JoshuaBixby ?

[JoshuaBixby]

This should work:

!DEFMAINTENANCE! - !COST! if !MAINTENANCETYPE! in ('DM General','DM Asset Protection','DM Priority Safety Concern') else !MAINTENANCECOMPLETE!