[GIS] Using Python if/then/else to return value from either of two fields based on value of third using ArcGIS Field Calculator

arcgis-10.0arcgis-desktopfield-calculatorpython-parser

I'm trying to avoid manually inputting Begin and End engineering station values already inputted into a seperate field.

I'm dealing with(4) fields:

Begin_Sta
End_Sta
Beg_End and
Station.

The Begin_Sta and End_Sta fields have engineering stations. The Beg_End field has either "BEGIN" or "END" inputted. The Station field is the one I want to populate using python in the field calculator.

If Beg_End has "BEGIN" then the engineering station value in the Begin_Sta field is returned into the Station field, else the End_Sta value is used to populate the Station field.

Is this possible using python in the Field Calculator?

Best Answer

Yes it is possible, right click your 'Station' field and select Field Calculator. Select python as the parser and check the Show Codeblock box, see screen capture below for code snippet:

enter image description here

Related Solutions

Remove Newline Character Python – Removing Return/Newline Character from Field Using Python

I think this is just a bug/limitation of the Python parser with the field calculator/Calculate Field tool. If a newline is encountered within the text field, a SyntaxError: EOL while scanning string literal occurs no matter what you try.

I can reproduce the issue at 10.1 SP1 by importing the following CSV file into a file geodatabase, adding a field and simply attempting to copy the Text field to the new field using the Field Calculator with the Python parser and and the expression !Text!.

ID,Text
1,"this is a multiline 
example"

Try switching to the VB parser, or using an UpdateCursor and avoiding the Field Calculator entirely.

This issue is also discussed on the ESRI forums, with the same conclusions:

End-of-line (EOL) Problem

The only relevant NIM I could find was this:

NIM085499 - CalculateField calculations using non-ASCII characters fail on a Linux engine with: "ERROR 000539: SyntaxError: EOL while scanning string literal (, line 1)".

[GIS] Writing If-Then Statement in ArcGIS Field Calculator using Python Parser

Using Python, the calculation would look like this:

For the Pre-Logic Script:

def Calc(a,b,c):
 if a == "000":
      return b
 else:
      return c

For the expression:

Calc( !A! , !B! , !C! )

Best Answer

Related Solutions

Remove Newline Character Python – Removing Return/Newline Character from Field Using Python

[GIS] Writing If-Then Statement in ArcGIS Field Calculator using Python Parser

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