Using ArcMap 10.4 here and having some trouble running some python code in the field calculator.

I am trying to populate one text field based on the value of another text field. Here is what I am entering into the field calculator:

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When I attempt to run this I get the error:

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I am using 2 spaces for the 'if' line and 4 spaces for the 'return' line. Maybe I'm missing something big, brand new to coding here so any help would be great.

  • 1
    Give four spaces a go. If not try tabs.
    – Emily
    Commented Aug 4, 2017 at 16:03

2 Answers 2


A single = sign is for assignment, == is for comparison. Change your if statement to if luCode == 'BF':.

4 space indentation is suggested, but not required. Consistency within an indented block however, is required.

  • Hmm unfortunately that didn't work. After using the == I got error 999999 @bjorn Commented Aug 4, 2017 at 17:43
  • Got it to work. It was a combination of using the == and using a 4 space indentation for the 'if' line and 6 for the 'return'. Not sure why it was required in this case. Thanks for your help! @bjorn Commented Aug 4, 2017 at 17:59
  • @Tigerwoulds If you consider my answer to be the correct one you should mark it as such so that others can benefit.
    – Bjorn
    Commented Aug 4, 2017 at 18:03

The answer is 2 parts:

  1. As @Bjorn mentioned, I needed to use an == as opposed to an =

  2. I am missing an 'else' statement which is preventing the code from running; As soon as I added it, everything worked as it should. Spacing needed to be consistent but 2 vs 4 space indentation wasn't a factor.

  • You do not need an else there, it is implicit. Anything return ing after your if block will function as such.
    – fatih_dur
    Commented Aug 6, 2017 at 16:06
  • I get the same error unless I include an 'else return none' at the end Commented Nov 17, 2017 at 15:51

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