All Questions
7,900 questions
10
votes
2
answers
4k
views
Reprojecting layer using PyQGIS
I'm trying to find a very simple solution to reproject a vector layer into a temporary layer in PyQGIS, however documentation is really extensive and I'm fairly new to PyQGIS; the only answer I've ...
- 3,528
10
votes
3
answers
10k
views
Using QGIS Zonal Stats Plugin from Python Console?
I am using the Zonal Stats plugin in QGIS to extract raster statistics from overlaying polygons (I have shapefiles of species distribution and I want to extract environmental data from within each ...
- 567
10
votes
2
answers
2k
views
Setting QGIS to "show feature count" always when layer is loaded?
I am using QGIS 3.
I know that i can right click the layer and check the "show feature" option but is it possible to show enable this function by default when any layer is loaded ?
I know that we ...
- 2,770
10
votes
1
answer
201
views
Explaining long computing time of Python code
I have a Python code adding information to a layer if its features are overlayed by other features. The base layer has 1200 features and is 10 MB. The 4 layers for the overlay have roughly 40 MB ...
- 567
10
votes
1
answer
1k
views
Selecting features with equal field value interactively on QGIS map
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 ...
- 113
10
votes
1
answer
16k
views
Removing a vector layer from QGIS [duplicate]
Considering my program is generating a shapefile that has to be added to the "Layers" tab in QGIS interface. However, once the utility of the layer is completed, I need to remove the layer in the ...
- 1,445
10
votes
1
answer
4k
views
Getting canvas' extent coordinates using PyQGIS
I'm trying get the extents of the current map canvas. CRS is 22700 BNG.
My code:
canvas = iface.mapCanvas()
print(canvas)
vLayer = iface.activeLayer()
extents = vLayer.extent()
print(extents)
Which ...
- 955
10
votes
2
answers
6k
views
Returning latitude and longitude of point using PyQGIS [closed]
I have a point layer, that I'd like to return the Longitude, latitude using the PyQGIS.
How do I use QgsPoint to do that?
- 8,563
10
votes
3
answers
17k
views
Loading raster layer in a standalone PyQGIS script
I need to load a raster file from the provided file path. I wish to use it further in the Raster Calculator.
I wrote a function which converts string (I assume it is a file path) to a raster object.
...
- 681
10
votes
2
answers
6k
views
Does mapCanvas().refresh() not work in QGIS 2.6?
Before I used the function
qgis.utils.iface.mapCanvas().refresh()
to reload the map canvas after for example a layer color was changed from a plugin.
But this is not working with QGIS 2.6 for me.
...
- 2,918
10
votes
3
answers
6k
views
Is it possible to change legend symbols in the QGIS print composer legend?
I have some layers with very complex data-defined symbols.
If I use a legend in the print composer these symbols are not drawn correctly.
Is there a way to change the legend-symbols with pyqgis, so I ...
- 8,936
10
votes
1
answer
1k
views
Selecting column like Primary Key in View from PostGIS using PyQGIS?
Postgresql doesn't support Primary Key in views.
When I load a postGIS view in QGIS "manually", I can choose the column that will be the Primary Key, but I would like to know if I can select a column ...
- 939
10
votes
1
answer
1k
views
Is it possible to have dynamic layer names in QGIS project?
I have a QGIS project with layers, based on PostGIS SQL queries that use current date. Since the data in the database changes, these queries return different data every new day.
Is it possible to ...
- 893
10
votes
1
answer
18k
views
Getting feature count of QgsVectorLayer using PyQGIS?
I'm using this code to get features from QgsVectorLayer
QgsVectorDataProvider* provider=theVectorLayer->dataProvider();
if(!provider)
{
return;
...
- 233
10
votes
2
answers
9k
views
How to compile QtDesigner user interface (.ui) and resource (.qrc) files with QGIS 3 on Windows?
I tried to transpose the QGIS 2 process with no success.
I first had to edit C:\Program Files\QGIS 2.99\etc\ini\python-core.bat which contains references to Python27 instead of Python36.
I run C:\...
- 879
10
votes
2
answers
899
views
QGIS crashes when doing a rollback after modifying values of an user-added feature with pyQGIS
I'm developing an addon for QGIS that needs to assign a UUID to any feature as soon as it is added to the layer.
I'm using the featureAdded signal to write the UUID in the corresponding field of the ...
- 281
10
votes
1
answer
704
views
How to create a geometry generator symbol using PyQGIS
I am trying to use PyQGIS to convert a Fill Symbol Layer into a geometry generator Symbol Layer in a rule-based renderer with 300 rules.
I am able to iterate over the rules and return each rule's ...
- 14.4k
10
votes
4
answers
2k
views
Is there is a signal in QGIS when a project is about to be closed?
Is there is a signal in QGIS emitted when a project is about to be closed (QGIS closing or some other project opening)?
I want to programmatically save changes in layers if they are in edit mode.
- 167
10
votes
1
answer
1k
views
Exposing variables to the Python Console from Plugin in QGIS
I have a QGIS plugin that performs a long-running operation, eventually producing and loading new shapefiles into QGIS. (I have this as a plugin rather than just a function that can be called from the ...
- 265
10
votes
1
answer
2k
views
Getting log message from QGIS processing framework?
I run Python processing algorithms externally, and I want to get the log output I see when I run it from the QGIS 3 GUI at the log tab as shown in the screenshot:
I want to get the full grey log ...
- 661
10
votes
1
answer
684
views
Programmatically turn on/off panels with PyQGIS
In QGIS, with right-click somewhere in the toolbar area panels can be toggled on/off like shown in the screenshot below (the GPS Information Panel for instance).
I need to do this programmatically, ...
- 14.9k
10
votes
1
answer
2k
views
Register custom qgsfunction in pyqgis
I'm using pyqgis within an standalone application.
Now I wanted to create a custom expression to to use as filterExpression in rule of ruleBasedRendererV2. (I tried the renderer with existing ...
- 906
10
votes
2
answers
7k
views
Creating memory layer and populate fields using PyQGIS
Seems like a basic operation using PyQGIS but can't see what I am missing. I want to create a memory layer with the exact same features and attributes from a shapefile. I have looked several posts ...
- 76.3k
10
votes
1
answer
6k
views
Using in-memory vector layer with QGIS processing / SEXTANTE
I'm trying to run the qgis:clip algorithm from console, but am getting an error when using an in-memory layer as the overlay parameter. Is this to be expected, or am I doing something wrong?
Code:
...
user23603
10
votes
1
answer
15k
views
Why can't I import my script from the python console?
i am working with the qgis python console.
I usually store all my python scripts into ~/Scripts/python
I do have set the PYTHONPATH to ~/Scripts/python in my .bashrc
However, I can not manage to ...
- 871
10
votes
1
answer
3k
views
Method for generating wedge buffer in PyQGIS
Is there any method generating a wedge buffer, as in Creating wedge buffers from many to one in QGIS, using QGIS Python API?
I made a search in QGIS API Documentation and GIS SE.
I'm not looking for a ...
- 78k
10
votes
1
answer
3k
views
Listing project layers in standalone PyQGIS script
I'm trying to load an existing .qgs project and get a list of the layers inside. I seem to be able to open the project, but I can't get the list of layers. I'm a little confused as to the basic PyQGIS ...
- 693
10
votes
1
answer
7k
views
When iterating over a vector layer with pyqgis, how do I check whether a feature is selected?
While iterating over a vector layer using the following code (summerized from the example in the pyqgis cookbook), is there a way to check whether a feature is selected?
provider = vlayer....
- 1,498
10
votes
1
answer
3k
views
Selecting subgroup in Layers panel using PyQGIS
I can select a group layer (for example C) using the following script. But I can only select groups in root level (A or C). I am struggling to select subgroups. I play with the script, but no success.
...
- 78k
10
votes
1
answer
3k
views
Adding PostGIS layer from QGIS Python plugin
I try to develop a plugin to add postgis layers to qgis from a plugin as part of learning python.
The code for adding a postgis layer is taken from the cookbook and work fine if I run it from the ...
- 1,765
10
votes
2
answers
1k
views
Closing attribute table with PyQGIS
I have a QGIS 2.18.0 plugin which updates a join between two layers (spatial and non-spatial layer).
QGIS crashes when I run the plugin and the attribute table of the joined layer is open. There is no ...
- 4,474
10
votes
1
answer
3k
views
Automatic pyqgis categorized renderer classification [duplicate]
I have some layers in my project and I would like to alter their styles, since ranges of values for underlying columns have changed.
Normally it would require to enter each layer style settings ...
- 303
10
votes
3
answers
10k
views
Setting the extent for a QGIS map using python
I am writing a stand-alone application in Python/QGIS that simply creates maps.
I want to load vector/raster layers, set symbology, set extent
At the moment, that is all!
Currently I am just using ...
- 637
10
votes
1
answer
2k
views
Zooming feature without selecting it using PyQGIS
When I need to zoom to a feature, I have to select it first using layer.select(feature.id()) then I can zoom using mapCanvas.zoomToSelected(layer).
layer = iface.activeLayer()
layer.select(1)
iface....
- 78k
10
votes
1
answer
3k
views
Accessing iface PyQGIS API from Standalone Python script (outside QGIS environment)?
I want to call PyQGIS API from my standalone Python script, outside QGIS environment. I can not, as 'iface' is not available.
I have done necessary import / initialization :
from qgis.core import *
...
- 113
10
votes
1
answer
4k
views
Creating raster layer from numpy array using pyqgis?
I am working on a plugin for Qgis to calculate spatial Kernel density maps. I have all the calculations working, all I am missing is a way to turn a Numpy Array, with density values into a multiband ...
- 1,247
10
votes
2
answers
4k
views
processing.getObject() in QGIS 3
It seems that processing.getObject() is no longer available in QGIS.
from PyQt5.QtCore import *
from qgis.core import *
#...
layer = processing.getObject(layer)
# -> ...module 'processing' has no ...
- 2,016
10
votes
2
answers
1k
views
Switch QGIS proxy settings programatically
I am using QGIS at two offices with different proxy-servers.
At the moment I have to change the proxy settings manually every time i switch the office.
I was wondering if its possible to change the ...
- 8,936
10
votes
1
answer
3k
views
Passing Geometry object to processing tool instead of Layer
In ArcPy, you can pass a geometry object as parameter to geoprocessing tool:
import arcpy
coordinates = [[20, 30], [30, 30], [30, 20], [20, 20]]
array = arcpy.Array([arcpy.Point(x, y) for x, y in ...
- 78k
10
votes
1
answer
2k
views
Splitting lines/creating vertex at intersection using PyQGIS?
I am looking for an easy way or function to split 2 previously selected line features (generate vertex) at intersecting points (or touching points). See the following picture:
I am developing a ...
- 101
10
votes
5
answers
1k
views
Minimum wall-thickness of a non convex polygon with holes
What is the most efficient way to find the minimal wall-thickness (value and location) of a complex, non convex polygon area including holes? See example of a polygon in blue, with the minimum wall-...
- 101
10
votes
0
answers
378
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 ...
- 8,953
10
votes
0
answers
5k
views
QVariant is not defined when using addAttributes [closed]
When I try to add a field programmatically with the following code:
import os.path
from PyQt4 import QtGui, QtCore
legend = qgis.utils.iface.legendInterface()
allLayers = legend.layers()
for i in ...
- 101
9
votes
5
answers
3k
views
Getting user's QGIS version using PyQGIS
I am trying to write a QGIS plugin, which should work on QGIS 2 and QGIS 3. How can I find out which QGIS version the user is using, so the right imports are made?
- 723
9
votes
3
answers
35k
views
Change Shapefile data source encoding?
I tried to change the only the shapefile datasource encoding through properties and also How to encode shapefiles from LATIN1 to UTF-8? but it doesn't change it.
Without saving the QGIS project can'...
9
votes
2
answers
11k
views
Activating layer by its name in PyQGIS
I'm writing a script that requires the attributes of different layers to work, and I would like to know how to call a layer that is not the currently active one and get its features.
For example, I ...
- 309
9
votes
3
answers
5k
views
Getting number of features in the Attribute table using PyQGIS
I have a layer and I would like to access the number of rows the attribute table has from my code. Is there a way to do that without doing it like this:
num_of_features = 0
for feat in layer....
- 91
9
votes
3
answers
8k
views
Accessing attribute data type in PyQGIS
I've been developing a Plugin on the QGIS platform using PyQGIS. So far plugin does the following: You can select any feature of the already loaded vector layer in QGIS. After selection, the plugin ...
- 155
9
votes
3
answers
2k
views
Getting provider name of layer using PyQGIS
In QGIS 3.16.5-Hannover, with PyQGIS I want to get the provider name of a selected layer. I need to know if it's an ESRI Shapefile layer or a PostGIS layer for example.
I don't see how to get this ...
- 1,656
9
votes
4
answers
20k
views
Deleting variables from the Python Console in a programmatic way?
I often use the Python Console for running some lines of code and I also use some prints for checking the validity of the results.
If I run this sample code:
a = 2
b = 4
res = a + b
print res
it ...
- 16.3k