I'm trying to create a basic model using QGIS, the QGIS graphical modeler and the sextante toolbar. In part of the model, I need to select features based upon multiple attribute values (for example – A = 'value' OR A = 'another value'). The select by attribute algorithm provided by QGIS only allows you to enter a single value at a time – is there a simple tool/method to enter an expression to select multiple values from a dataset, and which can be incorporated in the graphical modeler?
[GIS] How to select features based on multiple values in graphical modeler
qgisselectsextante
Related Solutions
Depends on the plugin.
Some plugins are designed to be integrated with the Processing Framework such as the GeoServer Explorer Plugin which contains several tools readily accessible from the Processing Toolbox and modeler.
However, I think currently most plugins do not possess this level of integration.
Use a custom script.
There have been a number of posts here asking how to access such plugins using Python (or the modeler):
- Is there a way to access QGIS plugins in Python?
- How to call the interpolation plugin from the python console?
- How to use Qgis Gridsplitter Plugin in Console
- Access all plugin from QGIS Modeler (Sextante)
Again, some plugins can be easily called using python scripts but others not so, you will need to examine the source code.
But if a plugin can be accessed easily, you could create a custom script in your modeler which would contain the code necessary to call the plugin.
If you want to define an input as a variable, first create an input, than use this input with Set project variable, give it a name and use the value of the input with Using model input (see screenshot).
You can than use this variable with it's name in select by expression. Be sure that in the Select by expression dialog box (bottom left on the screenshot) under Dependencies you have selected the Define variable algorithm. Otherwise, you have to run the model twice to update the variable to the new input.
Running the model with input character a: all features with attribute name starting with a are selected:
If you have a pre-defined project-variable, this solution applies:
You forgot the '%' part. Use this expression:
"gemnaam" ILIKE @firstchar || '%'
Or use this alternative:
left ("gemnaam",1) = @firstchar
Best Answer
Just to move this question from the Unanswered section - the Sextante plugin has been renamed to the Processing plugin.
And as of version 2.9.0, you can use the Select by expression tool (separately or within the graphic modeler) which allows you to select features based on the expression provided.
This can include multiple attribute values, for example: