Questions tagged [qgis-modeler]

An application of QGIS used to develop models utilizing a large variety of powerful Geoprocessing tools via a GUI.

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Using input vector field in QGIS python script

I have created a QGIS Graphic Model using built-in Graphic Modeler. My model is supposed ask the user for an input layer, an overlay layer, and fields from the overlay layer. The model then should ...
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1answer
21 views

QGIS dissolve algoritm: how to select multiple field in modelbuilder

I am trying to make a model in the processing modeler of QGIS. I need a step where a layer with polygons is dissolved based on two fields. At the moment I do this manually. When I open the dissolve ...
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1answer
54 views

Connecting number parameter to Field Calculator in QGIS Modeler

I intend to develop a model with field calculator processing using the QGIS Modeler. How do I include the number input by the user to be as a value in Formula of Field Calculator? This is the model ...
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2answers
128 views

Definitive list of QGIS multiprocessing tools?

This question is not as straightforward as it seems, but can be summed up with the following: Is there a definitive list of geoprocessing tools for QGIS that currently support multithreaded ...
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14 views

Processing Modeler QGIS Issues With Interpolation Step

I am trying to interpolate Sampled Points with IDW Interpolation in the QGIS processing modeler. For some reason I am not able to select the Sampled Points with the IDW Interpolation. Anyone know ...
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1answer
57 views

Using QGIS Processing Modeler to split polygons with lines

I am trying to use the QGIS Processing Modeler to split polygons with lines. Here is the workflow I have so far. It is sucessful. I then add "Grid" and "Split With Lines" to split the polygons. ...
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20 views

Calculating percentage overlap in graphical modeller

Can anyone help me calculate the percentage overlap of a polygon with multipoint attributes (I.e fragmented pieces of polygon overlapping) in graphical modeller? I need to calculate the area of my ...
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1answer
65 views

Exporting map layout from QGIS modeler

I am trying to write a processing script that takes a template file as input and writes out the current canvas content as a PDF. The processing script works fine. But when I use the script in a model, ...
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32 views

Dealing with empty parameters in QGIS

I'm building a graphic modeler in QGIS. I need to model adding multiple fields/columns to a layer and then importing values from other fields/columns into those new fields. Example : Existing field ...
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1answer
45 views

Using Python Code from QGIS modeler with if and else

I am using QGIS 3. The following script code is generated from a model. At the end the code has to create a field Fl_m2, if the blnFl is true. if ['blnFl'] is True: If it is not true the ...
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1answer
47 views

QGIS custom script to run one process or another depending on input

[QGIS 3.10] I have two processes I have created using the graphic modeler. I'm trying to create a script that would run one process or another depending on the inputs. But I'm getting an error in line ...
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1answer
77 views

QGIS 3-->Python-Code from graphic modeler doesn't work

I run a model with an if-condition with sucess. After exporting the code the scirpt gives me an error: "Unable to execute algorithm Field name is not set. Please enter a field name". the code-snippt ...
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1answer
53 views

QGIS Processing Model with IF script

I have a QGIS model that I want to modify with an IF personalised script. Basically one of the inputs is optional, but if it's empty then the model is throwing some errors down the line. Hence the ...
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0answers
36 views

Empty result while running Processing Modeler

There is one polygon layer, see image below I am simply trying to achieve all the holes as polygons with the following step-by-step algorithm Dissolve all Delete holes in the output of 1 Difference ...
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1answer
47 views

Graphic modeler with if Statement

Is it possible to use a boolean as an input and if it is true then the field will be created?
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0answers
32 views

Dropdown option in QGIS 3 processing modeler input?

I have an Excel spreadsheet with multiple sheets of different XY database. I made a processing model in QGIS 3.10, in which I have used 'make points from table' tool to create a point shapefile. But ...
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0answers
29 views

Combining graphic modeller Python output with another Python Script

I created a model that takes my point shapelayer, creates polygons from these points using minimum bounding geometry then adds a field named 'Zonekey' to attribute table; from qgis.core import ...
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1answer
36 views

QGIS: Selecting active layer to be processed in Python script exported by Graphic Modeller

I created a model and I would like to have it as a python script. This is what I see when I run my model and I can select a layer from this window. I don't necessarily need to select a layer, it can ...
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1answer
50 views

Using Python script inside QGIS Graphic Modeler and iterating over all features

I created a graphic model which simply creates multiple vector attributes. All attributes are empty to be filled manually. Only one attribute column (let's call it KEYS), needs a different process and ...
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2answers
38 views

Combine columns passed as parameters in QGIS graphical modeller

I would like to combine two fields in QGIS using graphical modeller. If I were to do it using field calculator, I would do it as follows: "field1" + ", " + "field2" Unfortunately, I cannot do it, as ...
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153 views

Is it possible to rename a table column with an expression in the field calcultor of QGIS?

I want to be able to rename a few column names with an expression in the field calculator in order to be able reproduce this action with the QGIS graphical modeler. I tried to do this with the ...
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1answer
41 views

Group by 2 fields in “Add autoincremental field” in QGIS Modeler

I'm creating a model in Modeler in QGIS3.4. I want to use a "Add autoincremental field" tool. I want to group my field by two other fields (it works when I set it "normally", not in Modeler). I think ...
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1answer
49 views

QGIS Processing Modeller - Select date by expression

I have a data file that contains current meter data for multiple days. I am trying to use the Processing Modeller to extract a single days worth of data for further manipulation, using the extract ...
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1answer
46 views

Incorrect Result Output Layer Name from Python Script

I have exported this code from Graphic Modeler of QGIS as a python script. The Model is outputting the final result as CN_Grid, as it should, but the script of the same model is giving results as ...
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1answer
46 views

Converting Python Script back to a Graphic Model in QGIS Graphic Modeler

I created a model in the QGIS Graphic Modeler and exported it as a python script. I made a few changes in the python script and now want to export it back to the model. Is it possible?
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1answer
67 views

Using Boolean Parameter in QGIS Graphic Modeler

I am trying to create an if/else condition with a boolean parameter in QGIS graphic modeler. The parameter will be used inside Field Calculator2 algorithm.By default the parameter is False. I am ...
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1answer
46 views

How to Embed a table into QGIS Graphic Modeler?

I am automating a process in QGIS. So far, I have built the following model. The HSG Lookup.csv is a user input right now. But I want it to be a predefined table(or csv file) embedded into the model ...
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0answers
44 views

Multiple centroids of complex outline polygons by recursive buffering

How can I algorithmically determine multiple centroids for overlapping (dissolved), very irregular regions representing canopy outlines? This is effectively a forestry issue. The context is that I ...
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0answers
52 views

Use QGIS field calculator raster_value() function inside Graphical Modeler

I need to use the raster_value() function (from field calculator) inside a graphical modeler workflow. The function works if the raster is already loaded on QGIS, and then calling the raster name on ...
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1answer
75 views

QGIS: Processing Modeler - Field Calculator uses the input Layer

I'm trying to measure horizontal and vertical difference between consecutive points in a layer. In the following link you can download a WinRar file with a shapefile and my model to test in QGIS 3: ...
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0answers
25 views

Deleting input vector or raster being used in QGIS 3 modeler

As it is explained in the title I am writing a script to process this task. The script is already written but I need it to be triggered when the inputs are not needed anymore. In other words : I need ...
2
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0answers
34 views

Loading CSV file without geometry in graphical modeler

I'm trying to use the graphical modeler to make a join between a vector point layer and a CSV file which doesn't have geometry data. I tried to use 'Vector layer' as an input for the CSV-file but the ...
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1answer
38 views

QGIS Raster calculation fails in Graphical Modeler

I'm trying to use the graphical modeller to automate a certain process (extracting North-South facing slopes from a DEM). The process is as follows: Calculate Slope Calculate Aspect Extract North-...
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32 views

Can Project Home variable be used to save default outputs of QGIS graphical modeler

Is it possible to use the @project_home variable in QGIS to set a default file path location for an output in the graphical modeler? Ideally I would like the default to be the project home folder ...
2
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1answer
52 views

How to delete features selected by expression using graphical modeler in QGIS3

I can't find an algorithm for deleting features (points), so I can't delete features in the graphical modeler. I found related information (Select by expression and remove points). However, I want to ...
2
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2answers
89 views

QGIS expression, define start and step increment

This is a continuation of the question QGIS Extract by Expression with multiple polylines in Processing Modeler I have polylines with increasing values, Gabriel De Luca helped me to automate the ...
3
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0answers
29 views

Exporting rendered raster image from graphical modeler

I am new to using the graphical modeler and am trying to export the result raster from my model as a rendered image. Basically trying to replicate what happens by doing the following to the result ...
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2answers
152 views

Converting selected polygons to lines in QGIS modeler

I have a vector file which I would like to add using "add Vector Layer" (the vector file is a polygon). I would like to convert the polygon file to lines, however only selected polygons. I had an ...
2
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1answer
18 views

Add an attribute name as parameter in refact - QGIS 3 modeler

I'd like make a model where I can change an attribute name to a predefined one using refact tool. How can I get that "attribute" by a parameter from a vectoral field ?
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23 views

Set the Output of a script as Input of another one

What is the correct way to call the output file of a script? Since QGIS can't name it automatically. I have this script that works perfectly, just drop a file identical to the original. from qgis....
2
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1answer
54 views

Ask for polygons but getting points with QuickOSM in QGIS Modeler

I am attempting to download both points and polygons using QuickOSM+modeler in QGIS 3.10 (also tried QGIS 3.8). It's downloading the points fine, but when I attempt the same thing with multipolygons ...
2
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1answer
42 views

Qgis SAGA Upslope Area for several points automation

In the Upslope Area tool from SAGA it used to be possible to import the point file with multiple points and it would create several catchment/basins areas for those points. Now, it is only possible to ...
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1answer
30 views

Creating Dialog with Graphic Modeler for Attribute Creation

I have a shapefile with an attribute that I need to convert based on categorical rules. Hereby the TARGET / new values always stay the same and only the input values change. For example: "Residential ...
3
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1answer
114 views

QGIS Extract by Expression with multiple polylines in Processing Modeler

I'm trying to get the matching features from an intersecting vector layer. I can manually open Extract by expression tool and put the expression like intersects($geometry, geometry(get_feature('Liness'...
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0answers
18 views

Processing: Using attribute as input for algorithm

In Processing Modeller, is it possible to pass a field value (attribute of a feature) to a file name? Example: I have raster, MyRaster.tif, and I would like to clip it by different polygons inside ...
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0answers
39 views

Manually giving input and output for QGIS graphical modeler exported python script

I am using QGIS 3. How could I manually give the input layer and the output path to the following script extracted from the graphical modeler? It is a simple model, it takes a DEM as input and ...
2
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0answers
44 views

Using Python code from QGIS 3.x Graphical Modeler in console?

I want to use "Join Attribute by Location (summary)" processing algorithm in Python console of QGIS 3.10. After design my algorithm process (join sum of field name "abc" form layer 2 (point layer) to ...
6
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1answer
284 views

Extracting features with equal field value using graphical modeler of QGIS

Is it possible to automate the following procedure with graphical modeler in qgis 3.4 or is it easier to perform such action with a python script using PyQGIS? Identify a feature (a line) in a vector ...
2
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1answer
57 views

Sort or add Rank within QGIS 3 model

I have the following function in order to add a sorting value to a layer: array_find( array_sort( array_agg("field")), "field") This works fine if I use it through the calculator within the ...
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0answers
64 views

Error while running batch processing in QGIS 3

I have built a straightforward model in the Graphical Modeller in QGIS 3.4 to select features by expression and then save the selected features to a new shapefile. It works when running singly but ...

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