15
votes
Accepted
15
votes
Accepted
Listing multiple fields to be dropped at once in QGIS modeler?
You need to separate them via semi-colons:
field1;field2;field3
- 27.9k
14
votes
Modeling iterative processes in QGIS 3
You need to use the Vector Features input parameter if you want to iterate over all or selected features:
Now when you run the model, you can choose whether to run the model once on all or selected ...
- 76.3k
14
votes
Accepted
Merging multiple temporal inputs in QGIS Graphical Modeler
Change your input back to the 123 Button (="Value-Input"). If you then click on the three dots ... to the right of the input line, you can choose your layers. Here, all layers from your ...
- 35.6k
13
votes
Accepted
Splitting vector layer based on attribute value in QGIS
A little dig in the processing algorithms and you can find Split vector layer geoalgorithm.
It takes a vector layer and an attribute and generates a set of vector layers in an output folder. Each of ...
- 3,340
12
votes
Accepted
Execute a field calculation on just selected records from Processing Toolbox in QGIS 3?
You can use is_selected() function in if statement to perform calculation on just selected features.
- 78k
12
votes
Accepted
Graphical modeler calculator missing in QGIS3
You can use expression within a model. For instance, my distance is in kilometers. But I want to do my buffer with meters.
Next to the distance field in the buffer algorithm, you can choose an ...
- 7,447
12
votes
Accepted
Defining the geometric predicate as a dropdown-input of a model
The geometric predicate input expects an index, starting from 0 as input as array or comma separated string. E.g. '1,3' or [1,3] for contains and touches. Since using numbers is not quite intuitive, I ...
- 35.6k
11
votes
Accepted
Opening old QGIS model in current QGIS versions
Processing in QGIS 3 was refactored a lot and many algorithms were
changed. So it is not possible to covert old models into new format.
You need to recreate it.
says Alexander Bruy, QGIS contributor, ...
- 78k
11
votes
Accepted
Count number of features in a geopackage and write to a file
I had done something similar with python. The script loops recursive through the directories starting from the startdir and then opens each geopackage and reads the gpkg_contents table - containing ...
- 11.9k
11
votes
Accepted
Refering to the input-layer of a QGIS model in field calculator expression
The trick to be able to refer to the layer-name of an input vector-layer inside an expression, using a model, is to rename the input layer.
Add a Rename layer algorithm, for the layer use Model input ...
- 74.9k
11
votes
Accepted
Selecting features visible in map extent using QGIS
The trick is to create a function that access QGIS graphical interface, and that is piped to the query of the select by expression.
Open a function editor (from anywhere, including from field ...
- 43.1k
10
votes
Accepted
Conditions in modeler field calculator
Create a new script from:
Processing Toolbox > Scripts > Tools > Create new script
Use something like the following:
##Example=name
##Layer=vector
from qgis.core import QgsField
from ...
- 76.3k
10
votes
Selecting polygon with the largest area in QGIS
You would be better off using "Select by expression" instead of "Select by attribute". Your expression should be something like:
"AREA" = maximum("AREA")
...
- 1,986
10
votes
Accepted
Why "Export as Python script" button is unaccessible in QGIS 3.0/3.1 Modeler by default?
This was intentionally disabled by commit 4f2a464
[processing] remove obsolete code and disable exporting models as
script until we update it so support new scripts format
@alexbruy alexbruy ...
- 69.6k
10
votes
Accepted
Using variable in graphical modeler for raster calculation? (QGIS 3.8)
SAGA
For the SAGA raster calculator, you can set the Formula option to read the value from your Number Input parameter:
In the Formula option, set the drop-down menu to Pre-calculated Value. The ...
- 76.3k
10
votes
Accepted
Processing tool to invert/switch selection in Graphical Modeler
Yes, you can use "select by expression" tool and insert if(is_selected() is false,true,false) as expression. This will allow inverting your selection in graphical modeler.
Result:
- 35.6k
10
votes
Adding a point to an existing layer
Create a new point using Geometry by expression, than Merge vector layers to merge this newly created point layer with the inital points layer. Here you can download the model for this workflow.
For ...
- 74.9k
9
votes
Accepted
QGIS Modeler if/else condition, custom script for Modeler
As mentioned in my comment, a custom script may be the way to go in this situation. You can create one from:
Processing Toolbox > Scripts > Tools > Create new script
The following script ...
- 76.3k
9
votes
Accepted
How to delete features selected by expression using graphical modeler in QGIS3
I believe it is not possible to delete features in the modeler, in this case use the extract by expression and put an expression that generates the opposite result of your current selection.
This ...
- 1,118
9
votes
Workflow automation for populating QGIS Attribute table
There are several options I may refer you to:
"Field calculator" : qgis:fieldcalculator
Opens the field calculator. You can use all the
supported expressions and functions.
A new layer is ...
- 34k
9
votes
Merging multiple temporal inputs in QGIS Graphical Modeler
I'm on QGIS 3.18.2, array() works for me. Consider this model:
You are on the right track with expression, in my case it looks like
following the hint "Expected input: an array of layer paths, ....
- 14.9k
9
votes
Joining dangling end in the vector layer using QGIS
You can use "Snap Vertices to Nearest Points by Condition" Processing tool from ProcessX PlugIn.
It is made for this purpose. Before running it, just extract the vertices of your lines via &...
- 35.6k
9
votes
Accepted
How to create a Virtual Layer using the QGIS Modeler?
You can use the tool Execute SQL. It is not a Virtual Layer per se, but hopefully it allows you to do what you need.
- 17.9k
9
votes
Accepted
Accessing layer properties for expression syntax in QGIS Modeler
You can use Raster layer properties:
@Raster_layer_properties_PIXEL_HEIGHT > 15
The conditions are used as dependencies to the following tools:
If the input raster has a pixel size above 15: ...
- 77.8k
8
votes
Using QGIS 2 processing model in QGIS 3
I fear there is no simple way to convert geoprocessing models from QGIS 2 to 3. Simply converting it from json to xml can be done with services like http://www.utilities-online.info/xmltojson/ but the ...
- 14.9k
8
votes
Accepted
Import csv with x y coordinates in QGIS 3 modeler
This workflow needs the csv-layer added into the layer panel before.
QGIS 2.18 Workflow
from Inputs you add a Table (Picture Nr 1. - 2.)
add "Points layer from table" (Nr. 4)
2a. define x and y ...
- 836
8
votes
Accepted
Writing comments in QGIS Graphical Modeler
You can use the help text editor (button next to green "play" button) to edit informational metadata with your model:
- 66.5k
8
votes
Accepted
QGIS 3 Graphical Modeler field calculator with attribute's parameters
Use the normal Field Calculator and in the Formula option, select Pre-calculated Value. Then use the expression:
'(' || @a || ' + ' || @b || ') / 2'
where the parameters @a and @b are the fields you ...
- 76.3k
8
votes
Converting Model in Plug-in in QGIS
To create a plugin from a model, use the "Plugin Builder" plugin.
By following THIS tutorial, you can build a basic structure.
On the third screen for plug-in creation, define the template as Process ...
- 1,118
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