How to use ElseIf conditional statement in QGIS field?
I have used an example I found online: I modified the statement as follows: This statement would not run, the Output preview stated Expression is invalid. The more info stated: Parser Error: syntax error, unexpected COLUMN_REF, expecting WHEN or ELSE or END
How are if statements used in field calculator?
The Field Calculator uses IF statements to calculate new values in the field of an attribute table. This article describes some common uses of IF statements in the Field Calculator and with Python scripts. To access the Field Calculator, refer to ArcMap: Making field calculations for more information.
How to create a virtual field in QGIS?
You can also create a virtual field, which will automatically return an updated value in case the values in cat change (e.g. you edit the layer). Remember that the values of virtual fields will not be saved in the dataset and are only visible inside this QGIS project. I just tested this : You can use the condition several times:
When to use a elseif in a modified statement?
You have a few problems in your modified statement. You don’t need quotes around column names. You’re using an “ELSEIF” when it should be a “WHEN”. The following should resolve all three issues and works for me in 1.8.0: Thanks for contributing an answer to Geographic Information Systems Stack Exchange!
How to write a conditional expression in Python?
So you should write your conditional expressions using Python: Note: it’s possible to use the Advanced Python Field Calculator in Modeler, however you have to specify the source field (s) directly in its formula, because fields cannot be used as input parameters when using this algorithm.
Can you create a custom function in QGIS?
With the Function Editor you are able to define your own Python custom functions in a comfortable way. The function editor will create new Python files in qgis2pythonexpressions and will auto load all functions defined when starting QGIS. Be aware that new functions are only saved in the expressions folder and not in the project file.