Questions tagged [qgis-processing]

Spatial data processing framework that brings advanced analysis capabilities to QGIS.

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Store the filenames of .kml files into the attribute table of a shapefile

I have to be joining .kml files in a single shapefile. The problem is that the kml files comes with a name that when I convert it into a shapefile it is not kept in the attribute table. thus, I lose a ...
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Output layers order in QGIS Graphic Modeller (algorithm execution order / dependencies)

I created a simple model in QGIS graphic modeller that takes in input parameters like drive time ranges and start location and outputs 3 styled layers including "start_point", "...
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Use core code of QGIS in my own Python scripts

I would like to know if I can use the code of the default functions that come in QGIS, for example the Intersection function. When you click on the help button it redirects you to the user guide where ...
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How to Group Parameters in PyQGIS Processing Plugin

The PyQGIS Processing Plugin I'm writing has a lot of parameters, most of which are advanced and won't be necessary for most users. I'm concerned that a user will be confused if they see all these ...
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Splitting feature into layers which are overlapped in same layer in QGIS

My script needs to select each feature in layer. While selecting features I found some of feature are overlapped. Feature can be selected but cannot highlight in map canvas. Is there any plugin or ...
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1answer
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r.terraflow fails after using fill-sinks

I'm using QGIS 3.10.11 with GRASS 7.8.4, and the default SAGA version that's included with the QGIS standalone 3.10.11 installer from QGIS.com. I'm having an issue where r.terraflow fails after using ...
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2answers
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Select polygons containing particular attributes from points layer

I have thousands of polygons (buffers) in a single layer and I have a points layer containing tree species. The tree species points shapefile has an attribute called Tree_Type. I need to select only ...
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Finding spatial difference between two vector layers with multiple features in each layer using QGIS

I am learning on the job with QGIS. I have two state level vector layers with individual shapes for each county inside the state boundary. I am trying to identify the area differences between each ...
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1answer
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Detect yellow spots on an image [closed]

I have a big raster image (12 GB) and I would like to detect yellow stains on it. I did try the Zonal Statistics but it is almost impossible to find the right parameters in order to detect the stain. ...
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2answers
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QGIS Processing Plugin Generating Features with Attributes

I'm writing a QGIS processing plugin that creates a point feature layer. I'm able to add points to the feature layer just fine but the attributes I add don't show up in the Attribute Table after I run ...
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QGIS: Running field calculator from Python. Adding new calculated field

I would like to add a new field to a layer, creating a new memorylayer from the existing layer. Where I create a new field using the expressions that are available to the "Field calculator" ...
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1answer
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Polygonize area surrounded by buffer in QGIS

I have an automated system in QGIS that separates loops from GPX traces and works out their centroid using 'Polygonize' >> 'Keep N biggest parts' >> 'Centroids'. However, quite often it ...
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Running QGIS processing tools in the OSGEO4W shell using the qgis_process functionality, syntax errors

I am trying to run QGIS processing tools in the OSGEO4W shell using the qgis_process functionality. I believe this functionality is fairly new as I have been having a hard time finding documentation ...
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Using various script forms in Linux QGIS 3.12

In the last few weeks, I have noticed that various script forms in QGIS (3.12, Linux Mint 19.3) have strange cursor behaviour. Spaces in scripts are unevenly represented on the screen. This is hard to ...
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1answer
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Add X/Y coordinate format incompatible with viewshed tool coordinate format in QGIS

I am performing an r.viewshed analysis (id: grass7:r.viewshed) in QGIS 3.10.9 with Grass 7.8.3. My question pertains to the 'coordinates' parameter. When I use the r.viewshed tool in QGIS and select a ...
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1answer
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Which buildings have access to nature where more than 50% of the nature area is closer than 3km?

I have 1) a file with all the residential buildings in a small municipality and 2) a file with all the surrounding green areas. I'm having a hard time solving this because the residential buildings ...
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1answer
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Is there a simple table structure update procedure for a manipulated PostGIS layer under QGIS

I have an intensive data exploring session using Postgresql/PostGIS as a backend and try to explore the results using QGIS. Within QGIS I have a defined a "complex" style to show the results....
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QgsProcessingException: There were errors executing the algorithm

I have been trying to run the nearest distance to hub points process (https://docs.qgis.org/testing/en/docs/user_manual/processing_algs/qgis/vectoranalysis.html#qgisdistancetonearesthubpoints) in ...
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1answer
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Customize QgsProcessing output layer name

I' writing an own QgsProcessing Algorithm and I want to give the output layer in the registry a custom name instead of the default "Output layer". I want to do that during processAlgorithm(),...
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1answer
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PyQGIS algorithm qgis:joinattributesbynearest not found

After re-installing Windows and QGIS 3.14 it seems like some PyQGIS algorithms are not working. For example: processing.run("qgis:joinattributesbynearest", options) gives core....
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QGIS 3 Graphical Modeler pre calculated values using Advanced Field Calculator

I have a new model that tries to create a new column using the Advanced Field Calculator and pre-calculated values. I just seem not able to get the syntax right on how to populate the attribute using ...
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27 views

PyQGIS chaining consecutive processing algorithms timing Issue

I am trying to run the merge vector layers algorithm for multiple shapefiles. Then run the join attributes by location between a merged polygon shapefile and merged multiline shapefile. All files are ...
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21 views

Exported QGIS model does not work: Invalid input error

This question is linked to this one: QGIS Graphic modeler: Loading in all the layers I have a very complex model which converts a specific file (pmkl.json) which is a feature collection of points ...
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Creating Network Flow Diagram using QGIS

I have a Telecom cable network in Geopackage format. How do I create a Network flow diagram from which to represent the relationship between Fiber distribution hub to Network access point?
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QGIS Graphic modeler: Loading in all the layers

Currently I have special script/model, where I convert a geoJSON feature collection to some seperate shapefiles. There was small pre step and prerequisite, that I want to eliminate, normally we load ...
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Scatter plot in Process Algorithm

I am trying to plot a scatter plot in the Process Algorithm on a data frame to show the relation between custom data and used under the K-means algorithm. But every time I try to run it. QGIS gets ...
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Editing processing toolbox algorithm “Vector Layer Histogram” output

I have a vector/shapefile layer with around 1500+ individual symbols. Each symbol has an attribute 'EVIMean' that I need to use for a histogram and it is a numeric value. I first tried the default ...
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QGIS - graphical modeler aka. processing toolbox - update only selected fields

I have two layers: point layer representing some house addresses. polygon layer representing some kind of territory. What I'm trying to do is, create a model where I select the points inside the ...
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QGIS Layout/Print Composer: Automatic table refresh upon creation from template

This Question is related to this one: QGIS print layout: Pulling the name of the map theme from table Currently I have two specific templates I use for A3 and A0 plans both of them are structured the ...
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Using QGIS Processing-Toolbox in stand alone Python scipt (Microsoft Visual Studio)

I'm using QGIS 3.14, Python 3.7, Processing-Version 2.12.99 and Microsoft Visual Studio 2019 (IDE). Everything works fine, the only problem I have is the import of the processing-algorithms. Related ...
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Tools for fixing geometry of shapefiles

does someone have experience in fixing geometry errors in QGIS 3.10 LTR? I'd like to fix geometries first and then use processing algorithm "Snap geometries to layer". So far, the algorithm ...
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27 views

What is the best way to break up a shapefile into discretely sized tiles?

TL;DR version: I need to break up road vectors in QGIS to 4,033km2 tiles to import into an UnrealEngine landscape. I am evaluating a plugin the imports GIS data into UnrealEngine for a simulation. ...
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1answer
25 views

Using NNJoin-Plugin through Python console

I want to write a Python script which I can execute from within QGIS 2.18 (from the Python console). The Python script should calculate the nearest line (out of a set of lines) of a given point (out ...
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Fill nodata holes in discrete integer raster with majority value of adjacent pixels QGIS

I have a large land cover raster with classified integer values from 2-22. There are some single or double pixel no-data gaps where I merged 2 adjacent tifs together. If this were a continuous raster ...
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30 views

Processing toolbox won't open tools

Since yesterday the processing toolbox of QGIS 3.10.9 AND 3.14.15 won't open any tools. Originally, I wanted to use the select by location tool, but after trying no tool at all will open. It doesn't ...
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Error code using 'Proximity (raster distance)' tool

I have been trying to use this function following 2 teaching methods and get the same problem. I am trying to create a Boolean Raster layer from a previous Boolean Raster layer. The first boolean ...
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2answers
36 views

Access attribute names and add new attributes in processAlgorithm

How can I access the layer attribute names of the selected layer? I have tried checking on Google but all the methods are mostly for the previous version and I am using py3 version. att = source....
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Autofill field parameter based on parent layer in Processing Provider

I'm building a custom Processing Provider and would like my field dropbox to be dynamically filled with the first valid field of the associated parent layer. Currently, the dropbox list is updated if ...
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Integration R in QGis 2.18 in Ubuntu

I work in Qgis 2.18.17. I try to install "Processing R Provide" as it shows in video https://www.youtube.com/watch?v=nEJJE4DRiPQ&t=193s but as I understood it is usefull only for windows ...
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40 views

Accessing input layer when using “Selected features only” returns 'NoneType' object in QGIS 3 processing script

I am trying to write a processing script in QGIS 3.10.8 which would execute database function based on the selected features (or their id). I defined the input in a way that it accepts a point vector ...
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1answer
56 views

Save CSV with separator using PyQGIS 3?

I need save selected attributes of layer as CSV with separator. This is my code: def initAlgorithm(self, config=None): self.addParameter(QgsProcessingParameterVectorLayer('Input', 'Input', ...
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How to “merge” multiple raster ASTER L1T bands?

I want to generate a Land Surface Temperature map using ASTER products. I used the Semi-Automatic Classification plugin and followed this tutorial. However my study area is too large and required at ...
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How to run an exported QGIS program as a stand-alone application?

I have a research partner who exported their QGIS algorithm to a python script, and my job is to use that Python file to create a web application that provides access to that algorithm. My eventual ...
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2answers
92 views

How to insert missing vertex of two geometry overlaps area in QGIS

I need to add the missing vertex of two lines intersection places using QGIS.If any default plugins or tools available for fixing missing vertex in qgis,kindly suggest me. My Inputs: In above ...
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0answers
25 views

Adding multiple vector files in a folder as an input in QGIS processing modeler using iterator tool

I have shapefiles in a folder that I intend to use as an input in QGIS Processing Modeler. I would like to iterate within the folder to add each of the shapefiles as an input. It did it in ArcGIS ...
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1answer
59 views

Letting user select multiple fields from input layer for field calculator using QGIS Python Script

I am trying to build a script (python 3) where a user can select a number of numeric fields, define a set of numbers, and the script will create a new field after multiplying the field with the ...
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2answers
334 views

Errno 13 “Permission Denied” when running tools and plugins on QGIS

I am having an issue with multiple tools when using QGIS where I am constantly getting PermissionError: [Errno 13] Permission denied type errors. A lot of it seems to be associated with tools that use ...
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Interface customization in QGIS — I am unable to switch off the layer styling options of the layers

I tried to switch off the layer styling using interface customization option but it is still visible in the layers tab. How to we restrict the styling as the project file will be used by many users .
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QGIS 3.10 - Field calculator expression running in Attribute Table and not in Processing Modeler

I use the Field Calculator in the Attributes table and run the operation : "FieldA" - "FieldB", where "FieldA" and "FieldB" are height distances in meter with a ...
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1answer
57 views

Create Point based on location of minimum elevation inside a polygon in QGIS3

For QGIS3.0: Using DEMs, I am drawing polygons around depressions. Inside that polygon, I need to generate not only the minimum elevation value but the location that value was extracted from; this ...

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