Questions tagged [pyqgis]

Python bindings for QGIS.

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Remove reference to raster layer object PyQGIS

I am developing a plugin to load a set of raster files on QGIS. When there is a large number of files to be loaded, the main UI freezes. So I use QgsTask to move the creation of raster layers to a ...
mdc's user avatar
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12 votes
0 answers
1k views

PyQgis Exporting Print Layout: "ERROR 6: The PNG driver does not support update access to existing datasets."

I am trying to export a .tif loaded into a pre-configured print layout template and further exported as .png def openLayer(project, fp, basename, vector=True): layer = QgsVectorLayer(fp, basename) ...
Teabubblez's user avatar
11 votes
0 answers
451 views

Multithreaded DB connection for QGIS plugin

I am using QGIS 2.18.21 and PostgreSQL 9.6. on a Windows 8 machine. I am trying to do processing of a certain database task in the background, and I want the user to be able to continue to work in ...
Lennert De Feyter's user avatar
10 votes
0 answers
362 views

Defining partial or complete overlap with QgsSpatialIndex

I'm working on adding some functionality to a QGIS plugin. It currently uses a QgsSpatialIndex to efficiently compute whether the features of a vector layer intersect (potentially millions) of ...
alphabetasoup's user avatar
9 votes
0 answers
539 views

QgsRubberBand Move Event

I have created a QgsRubberBand which copies feature from layer. I need to be able visually move this rubberband on mouse event 'move'. Actually same visualisation like during self.iface....
justhateme's user avatar
8 votes
0 answers
415 views

QGIS contextual menu overriding

I would like to override the default contextual menu in QGIS 3 in the ToC. I've created a class that inherit from QgsLayerTreeViewMenuProvider. from qgis.gui import QgsLayerTreeViewMenuProvider from ...
TrsBar's user avatar
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8 votes
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2k views

Getting Spyder IDE to work with QGIS?

I was hoping someone could help me get Spyder working with QGIS. I am finding the python editor limiting within QGIS as I would like to debug my code, use the variable explorer, and be able to run ...
owl7's user avatar
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8 votes
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649 views

Setting up PyCharm CE 4 to work with PyQGIS library in Mac OS

I am trying to set up PyCharm to work with PyQGIS library. I am using PyCharm CE v4 and QGIS version 2.8 I have tried to implement the instructions of several posts like: http://osgeo-org.1560.x6....
Javier's user avatar
  • 221
7 votes
0 answers
235 views

QgsProcessingLayerPostProcessorInterface only processing the last layer

I have a QgsProcessingLayerPostProcessorInterface class as shown below. class LayerPostProcessor(QgsProcessingLayerPostProcessorInterface): instance = None name = "" color1 = ...
ar-siddiqui's user avatar
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7 votes
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869 views

Accessing the spatial index of a layer (shapefile) with PyQGIS

I built a manual index on a shapefile, through the process "Create spatial index", which can be found in the process toolbox > general vector tools. This process creates a persistent ...
Luis Perez's user avatar
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7 votes
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121 views

Why is QGIS holding references to layers that are not in layer list

I have a QGIS project, which has about 30 layers in the layer list. I removed one of the layers from the list, saved the project, closed QGIS. (The layer itself was from a Geopackage database, which ...
nr_aus's user avatar
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7 votes
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617 views

Writing layer to GeoPackage using PyQGIS

I have a PyQGIS script which carries out a number of operations on layers and writes the results to shapefiles. However, I understand that GeoPackages have a number of advantages (not having multiple ...
Stephen Poley's user avatar
7 votes
0 answers
498 views

Programmatically Enable/disable input parameters in a QGIS Processing plugin

Is there a way to enable/disable a parameter by a checkbox in the processing interface? In my screenshot below, I would like to disable the Output Wall Aspect Raster when the Calculate wall aspect ...
biglimp's user avatar
  • 196
7 votes
0 answers
847 views

QGIS crashes when running script from Processing Script Editor

Encountering this weird bug. I'm using QGIS 3.4.7. I am trying to write a script but it crashes when I run it from the editor. But it does not crash when run from the Processing Toolbox. Right now the ...
strythe's user avatar
  • 587
7 votes
0 answers
327 views

QGIS plugin external libraries in plugin’s directory

I’m developing my first QGIS plugin and I have to use two external libraries not included in the default OSGeoW64 installation: Couchdb and Pandas. I would like to include those libraries in my ...
Edoardo Pessina's user avatar
7 votes
0 answers
353 views

PyQGIS composed Atlas generation

I have some layers : layer 1 layer 2 layer 3 and I have create styles for any labels layer using base rule styles and labels and I have create a template .qpt and I use atlas correct. In my ...
jessie jes's user avatar
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7 votes
0 answers
1k views

Import Pandas or any Python module into QGIS internal Python

(Also asked in stack overflow - https://stackoverflow.com/questions/43244062/import-pandas-or-any-python-module-into-qgis-internal-python ) I am developing a plugin for the current LTR version of ...
jberrio's user avatar
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7 votes
0 answers
994 views

Gdal and module import error when creating an .exe application with pyinstaller

I’ve been struggling since three days in a row to create a windows executable application from my python application. I have managed to get results but I’m not at all satisfied with the workarounds I ...
vivek bouderlique's user avatar
7 votes
1 answer
1k views

How to load the layer style from PostgreSQL with Python

I would like to write a Python macro that upon opening my QGIS project file will reload the default style for each layer from the PostgreSQL 'layer_style' table. I have had a look at the documentation ...
Matt's user avatar
  • 2,706
7 votes
1 answer
3k views

Saving QGIS Project file (*.qgs) with PyQGIS?

I'm having trouble with QGIS (2.18.12) project files on Windows, if saved via Python command. The project file is saved via: project = QgsProject.instance() project.write() The file is saved, I can ...
swad's user avatar
  • 321
6 votes
0 answers
280 views

Making layer names in legend permanent using PyQGIS

While constructing a legend in Print Layout, I modify the names of the layers just in the legend, but not in the Layers panel (works as expected). Reproducible code is at bottom. However, after I ...
Andre Silva's user avatar
  • 10.2k
6 votes
0 answers
723 views

qgis_process run script from command line

qgis_process allows us to run scripts already installed in QGIS from the command line. But is there a way to run qgis scripts not yet installed? e.g. if I have a file script.py from qgis.core import ...
Sideshow Bob's user avatar
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6 votes
0 answers
138 views

Is it safe to access layer object(e.g. QgsVectorLayer) in background task(QgsTask) in QGIS3

I was confused if it's safe for developers to access QgsVectorLayer in a background task(QgsTask), like reading data from layers? Because descriptions in PyQGIS cookbook are different with different ...
Zac's user avatar
  • 517
6 votes
0 answers
223 views

Catching and canceling event when I press button using PyQGIS

I develop a script. When I select a feature from layer and press delete selected, I want to execute my function that checks something for this feature, and if the checker function returns False, it ...
Giotakon's user avatar
6 votes
0 answers
515 views

Open multiple QGIS projects via PyQGIS simultaneously in different threads

I'm writing a standalone PyQGIS application. When the method qgis() is called in a new thread, it's supposed to open a QGIS project (with one layer in it) and close it again: from concurrent.futures....
s74559's user avatar
  • 161
6 votes
0 answers
361 views

Applying graduated symbol renderer only on some features using PyQGIS

I have set up a graduate symbol renderer (QGIS cookbook - Graduated Symbol Renderer), and I am now trying to make it conditionally applied to some features only, depending on one (or more) attributes. ...
Leo's user avatar
  • 701
6 votes
0 answers
1k views

Exporting QGIS Atlas using PyQGIS (qgis.core)

Windows 10, PyCharm, QGIS 3.10 installed via osgeo4w (64bit). I set up a simple QGIS composer layout with a vector layer and a WMS base map on the map layout. The vector layer contains about 10 ...
Theo F's user avatar
  • 1,817
6 votes
2 answers
735 views

Added raster layers with PyQGIS do not show up

I have a list ("datList") with names of raster layers which I want to add. When I add raster layers in the Python Console everything works fine: for da in datListe: layerDir = "C:/[...
jannik schilling's user avatar
6 votes
0 answers
798 views

QGIS 3 Value Relation current_value() not working in custom ui form

I have a custom UI form made with Qt Designer with a couple of dropdown list, so I can easily edit a layer. I use a Value Relation on those fields to filter the displayed data. The problem is the ...
Daniel's user avatar
  • 61
6 votes
0 answers
329 views

Speeding up execution of PyQGIS algorithms

I don't understand why if I do "manually" some algorithms I get results much faster than when I insert the same in a PyQGIS code (with the same input). This happens, for example, with the ...
Sara Gaudio's user avatar
6 votes
0 answers
210 views

Indexing Data in QGIS

Each time I open a my project, it starts to index and takes as long as up to 4 hours at times. My project has some layers that are stored in a remote database. How do I bypass the indexing process?
Tafadzwa Booster Bere's user avatar
6 votes
0 answers
229 views

Defining shortcuts for QGIS plugins?

I'm writing a plugin using QGIS. I want to associate a shortcut to a procedure called "test". The code i am using is the following : self.shortcut = QShortcut(QKeySequence(Qt.Key_Q), self.iface....
Snaileater's user avatar
  • 5,723
6 votes
0 answers
219 views

Seeking list of project properties that can be written in PyQGIS?

The methods QgsProject.instance().writeEntry() and QgsProject.instance().readEntry() can be used to programmatically set project properties. According to the QGIS API reference the properties ...
TobsenB's user avatar
  • 912
6 votes
0 answers
305 views

How to handle large tables in QGIS using Python?

I'm currently writing a plugin that calculates values based on a QgsVectorLayer's attributes. To display and print the values I'm using a QgsComposerTextTableV2. I have several problems with my ...
Meibes's user avatar
  • 81
6 votes
0 answers
2k views

Connect to QGIS 2.6 Python Plugin function via button on custom feature form

I am trying to connect to a QGIS 2.6 Python plugin function via a custom feature form button. On my feature form, I'm attempting to do a few things : enable the updateButton only if the ...
user25976's user avatar
  • 2,115
6 votes
0 answers
883 views

Programmatically removing layer from QGIS composer legend without removing it from map canvas?

I am working on a QGIS Python plugin which includes automated map production. I use a series of map templates, each of which has a main map, an overview map (with a layer set different to the main ...
Patrick Maslen's user avatar
6 votes
1 answer
942 views

Print Composer Template produces empty map?

I have a print composer template which I'm trying to populate with different subset queries from a CSV-derived vector layer using the Python API. However, all the output PDFs contain everything except ...
Steve Pike's user avatar
5 votes
0 answers
72 views

Fully updating QGIS' GUI after changing a layer style via Python

Let's say I changed a layer's style via PyQGIS: # load "world" easter egg layer and then: layer = iface.activeLayer() layer.renderer().symbol().setColor(QColor.fromRgb(50,50,250)) Result ...
bugmenot123's user avatar
  • 10.8k
5 votes
0 answers
225 views

QGIS geometry editing listener

I would like to know if it's ever possible to make a listener on geometry editing. What I know so far is a geometryChanged signal that can be used in listening to layer when its feature's geometry is ...
Pavel Pereverzev's user avatar
5 votes
0 answers
104 views

Prevent PyQGIS from converting EPSG code to OGC URN

I'm trying to access the Sentinel Hub's WFS via PyQGIS. Here's my code: base_url = 'https://services.sentinel-hub.com/ogc/wfs/<my_service_endpoint>?' params = 'SRSNAME=EPSG:4326&TYPENAMES=...
Grigory Nedaev's user avatar
5 votes
0 answers
282 views

Loading layer from PostGIS with non-unique primary key

I'm trying to load (by mean of PyQGIS) a layer from PostGIS based on query involving a inner join with a non-spatial table. When I run the query in pgAdmin I get the desired output but when I ...
zakros's user avatar
  • 347
5 votes
0 answers
173 views

Changing feature attribute just after adding via QgsFeatureSink

How can I access a feature and change its attribute value, I just added to a processing-output before via sink.addFeature(feature, QgsFeatureSink.FastInsert)? Things like feature.id(specificfeatid)[...
MrXsquared's user avatar
  • 33.9k
5 votes
0 answers
165 views

Passing list as reclassify input table parameter in qgis.reclassifybytable algorithm

Following up on Save and load the classes definition table in the QGIS reclassify by table tool, I decided to run the qgis.reclassifybytable algorithm using PyQGIS to reclassify an aspect raster. Here'...
swiss_knight's user avatar
  • 10.2k
5 votes
0 answers
2k views

Using PyQGIS functions outside QGIS

I want to use PyQGIS function crs.isValid() in normal Python file outside of QGIS like this: wkt = 'GEOGCS["WGS84", DATUM["WGS84", SPHEROID["WGS84", 6378137.0, 298....
ar-siddiqui's user avatar
  • 1,738
5 votes
0 answers
152 views

PyQGIS: What objects need to be destroyed in a custom expression

I'm using a custom (PyQGIS) function in expressions to make little detailed minimaps around each feature in a layer, and store it in the layer (gpkg) as a png. My code works but makes QGIS (3.12) ...
Houska's user avatar
  • 7,978
5 votes
0 answers
218 views

QGIS processing tools - saving/exporting graph

I just tried QGIS processing tools for the first time. When using shortest path search for the first time, the algorithm is building a path graph (of course). However, the graph is never re-used. ...
Sane_or_not's user avatar
5 votes
0 answers
11k views

Getting layer reference using a feature

Using an existing feature, is there a way/method to get the layer which contains that feature? Example: # new empty feature which doesn't belong to any layer new_feat = QgsFeature() #---------------...
Kadir Şahbaz's user avatar
5 votes
0 answers
755 views

Create new MultiPolygon with PyQGIS

I want to create a new MultiPolygon shapefile, I tried this code Mp_Layer = QgsVectorLayer('MultiPolygon?crs=EPSG:26191', 'layer', 'memory') QgsProject.instance.addMapLayer(Mp_Layer) But when I ...
REDA DRISSI-EL-BOUZAIDI's user avatar
5 votes
0 answers
2k views

Selecting and deselecting features with PyQGIS

I'm trying to apply the algorithms "Random Points along Lines" at the feature level. I did some PyQGIS code to iterate through the features to select each individual instance and apply the algorithm ...
Leonardo Barleta's user avatar
5 votes
0 answers
77 views

Preserving provider of original raster layer when it is modified for another resulting raster layer?

A while ago, I asked for a method to assign new QgsRasterBlock objects to a QgsRasterDataProvider objects at Assign new QgsRasterBlock object to a QgsRasterDataProvider object. The reason was for ...
xunilk's user avatar
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