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I am trying to write function in QGIS via function editor and the problem is to call QGIS built-in functions e.g. azimuth, centroid... etc. When I run my script, I get 

'global name 'azimuth' is not defined'.

The same problem I got while I'm not specified module 'math' to function degree. My function code is on the picture:

here is my function

I imported different libraries, nevertheless function doesn't work. Does anyone have any ideas how to call these functions?

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  • Can you run the same "deg = math.degrees...." logic/statement within the QGIS python console without error?
    – artwork21
    Commented Jun 23, 2017 at 13:14
  • No, the result is 'NameError: name 'math' is not defined'
    – Jane
    Commented Jun 23, 2017 at 13:24

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You can't run the built-in expressions as they are defined in the Field Calculator framework. This means that any expression like azimuth, @geometry, centroid and so on won't work if you try to use them when building a custom function.

Instead, you need to use the common PyQGIS syntax as you were writing a script from the Python Console or the Processing Toolbox.

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  • Thanks!! I've found the majority of the Qgis expressions. But azimuth I' m not found yet anywhere
    – Jane
    Commented Jun 23, 2017 at 13:58
  • You may use azim = first_point.azimuth(second_point), where azim is the azimuth value and first_point and second_point are QgsPoint objects. Here you will find another example with the using of the azimuth function.
    – mgri
    Commented Jun 23, 2017 at 15:19

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