Questions tagged [pyqgis]
Python bindings for QGIS.
1,432
questions with no upvoted or accepted answers
13
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0
answers
535
views
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 ...
- 136
11
votes
0
answers
360
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 ...
- 1,217
10
votes
0
answers
533
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) ...
- 151
10
votes
0
answers
322
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 ...
- 7,763
9
votes
0
answers
439
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....
- 165
8
votes
0
answers
1k
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 ...
- 81
8
votes
0
answers
612
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....
- 221
7
votes
0
answers
101
views
QgsProcessingLayerPostProcessorInterface only processing the last layer
I have a QgsProcessingLayerPostProcessorInterface class as shown below.
class LayerPostProcessor(QgsProcessingLayerPostProcessorInterface):
instance = None
name = ""
color1 = ...
- 1,385
7
votes
0
answers
107
views
What does context mean in PyQGIS?
When writing PyQGIS scripts, especially processing script and expression function, I come across the term context. I use it, but I don't know what all contexts mean actually.
There are also Qgs***...
- 55.4k
7
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0
answers
338
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 ...
- 1,344
7
votes
0
answers
208
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 ...
- 463
7
votes
1
answer
219
views
QGIS 3.6 and QGIS 3.10 report different geometry types for the same shapefile
I used QGIS 3.6.3 to create a polyline shapefile, and the program reported the polyline as LineStringZM. When I opened the same shape file in QGIS 3.10.3-2, the polyline was reported as ...
- 143
7
votes
0
answers
584
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 ...
- 537
7
votes
0
answers
265
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 ...
7
votes
0
answers
334
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 ...
- 1,023
7
votes
0
answers
842
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 ...
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 ...
- 2,616
7
votes
2
answers
429
views
Multi-field labeling of shapefile with PyQGIS
I wrote the following code in order to draw the line labels with multiple fields. However, the label do not appear automatically in QGIS and I have to switch the "Layer Properties/Labels", ...
- 791
6
votes
0
answers
147
views
Adding a fixed table to layout in QGIS
I wonder how to add a fixed table into QGIS layout.
I've tried this solution but it doesn't work :
model = MyOwnQgsFeatureFilterModel(layout)
tableEnsemble = QgsLayoutFrame(layout, model)
...
- 123
6
votes
0
answers
186
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 ...
- 2,113
6
votes
0
answers
97
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 ...
- 61
6
votes
0
answers
70
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 ...
- 2,617
6
votes
0
answers
287
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....
- 151
6
votes
0
answers
221
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. ...
- 641
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 ...
- 1,365
6
votes
0
answers
230
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 ...
- 123
6
votes
0
answers
178
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?
6
votes
0
answers
2k
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 ...
- 311
6
votes
1
answer
747
views
Competing versions of GDAL
This is confusing, and a question I've harvested from a duplicate, so let me start with my setup.
OS: Windows 7 x64
GIS Client 1: ArcGIS Desktop 10.5
GIS Client 2: ArcGIS Pro 1.4
GIS Client 3: ...
- 1,325
6
votes
0
answers
864
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 ...
- 681
6
votes
0
answers
478
views
QgsRasterFileWriter.writeRaster() is crashing python program
I am doing NDVI analysis on a farm image. After NDVI, I need to convert the image into singleband pseudocolor image using following Python code.
def calculate():
file_name = CUR_DIR + "\...
- 181
6
votes
0
answers
292
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 ...
- 61
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 ...
- 2,035
6
votes
0
answers
862
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 ...
6
votes
0
answers
918
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 ...
- 325
5
votes
0
answers
42
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 ...
- 1,572
5
votes
0
answers
52
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=...
- 155
5
votes
1
answer
106
views
Internationalization of QGIS processing scripts
How can one translate QGIS processing scripts GUI and user messages to other languages ?
The QGIS documentation explains how to translate Python plugins, but not processing scripts.
- 137
5
votes
0
answers
100
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 ...
- 153
5
votes
0
answers
100
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)[...
- 24.6k
5
votes
0
answers
64
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'...
- 6,698
5
votes
0
answers
455
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....
- 1,385
5
votes
0
answers
392
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 Shape files. However I understand that GeoPackages have a number of advantages (not having multiple ...
5
votes
0
answers
106
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) ...
- 6,330
5
votes
0
answers
106
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. ...
- 81
5
votes
0
answers
332
views
Azimuth calculations - PyQGIS
According to the QgsDistanceArea docs, an azimuth for computeSpheroidProject should be
in radians, clockwise from North
So, to build a new point with computeSpheroidProject i use math.radians(...
- 93
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()
#---------------...
- 55.4k
5
votes
0
answers
410
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 ...
5
votes
0
answers
811
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 ...
5
votes
0
answers
52
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 ...
- 25.8k