All Questions
7,900 questions
8
votes
2
answers
6k
views
How to get pixel size/cell size of raster layer?
After much searching, I've still not been able to figure out how to perform what seems like a simple function: I'd like to get the pixel size/cell size of a raster layer using PyQgis. Is there any ...
- 103
17
votes
4
answers
17k
views
Buffering in PyQGIS
I'm looking for some examples to do simple python scripts in QGIS. How would I do a buffer analysis on a dataset?
I can't seem to find much in the manual and QGIS python that quite matches the ESRI ...
- 733
3
votes
1
answer
2k
views
Why are the features in my memory layer not displayed?
I am trying to create a memory layer, I followed the directions from the page below but no points appeared on my map. First I tried typing each line into the python console and I also create a plugin ...
- 2,210
1
vote
1
answer
404
views
QgsVectorDataProvider.createAttributeIndex() fails in QGis 1.8
Adding an Attribute Index to a Shapefile fails for a Python Plugin in QGIS:
For example - the following python Code in a Plugin
ly = QgsVectorLayer(data_source, layer_name,"ogr")
prov = ly....
- 75
7
votes
1
answer
2k
views
How do I allow users to select features with the mouse?
I am using PyQGis API to create a custom application.
How do I allow users to select features with the mouse? Is there a mapTool for this? Surely with a product as powerful as QGIS there must be.
- 71
9
votes
1
answer
4k
views
Calling GRASS modules in pyQGIS?
I wish to use a Grass module (v.to.db) in QGis, without the grass toolbox.
I tried with the Python console, but to no avail :
Using Sextante plugin but obviously it didn't know all the grass modules.
...
- 91
4
votes
1
answer
2k
views
Is there a straight way to copy or clone a QgsVectorLayer Object?
Is there a straight way to clone or "deepcopy" a QgsVectorLayer Object with python? Unfortunately the python module "copy" is not successful with that.
- 75
11
votes
5
answers
37k
views
Fixing "ImportError: No module named qgis.core"?
First of all, I'm using Python 2.7.3, QGIS 1.8 (Lisboa) on Windows 7 pro 64 bits. Now let's go to the actual question:
I have written some code (Python) that works well within the QGIS built in ...
- 111
2
votes
1
answer
1k
views
How to meet "Contour plugin" and "Profile Tool" dependencies in OSX?
So I have two similar but different issues than my previous question, one I may have mentioned already. When attempting to install the Contour plugin I am told I need matplotlib, which I have on my ...
- 99
2
votes
0
answers
169
views
How can I set python path and version for QGIS? [duplicate]
Possible Duplicate:
Couldn’t load SIP Module
When I'm starting QGIS I'm getting the problem:
"Couldn't load SIP module. Python support will be disabled."
And there is also:
Python version: 2.6.5
...
- 131
9
votes
2
answers
12k
views
How to show a message box in QGIS?
I am starting to develop a plugin for Qgis using python, which i am very new at, and would like to view some results of variables by displaying a message in QGIS. How can I do this?
- 2,210
6
votes
4
answers
2k
views
Iterating over selected layers using PyQGIS
In QGIS, by pressing shift or ctrl keys, a user can select multiple layers in toc.
How can a Python script iterate over selected layers?
I'd expect an iface.selectedLayers() but I can find only iface....
- 87
3
votes
3
answers
1k
views
Can I Dynamically Update Symbol Ranges?
Background: I'm currently trying to dynamically change the ranges for a layer with new style graduated symbology.
Problem: I thought it may be as simple as updating the ranges for the existing ...
- 700
2
votes
2
answers
790
views
How to do a spatial search without select() using PyQGIS?
Using QGIS 1.9.0-master, I want to do a spatial search for features in a vector layer without selecting them, i.e., without using QgsVectorLayer.select(), QgsVectorLayer.selectedFeatures() et al.
...
- 159
4
votes
1
answer
896
views
Count the number of symbols in a 'new symbology' renderer from pyqgis
Background : I create a lot of symbology using 'saturation' ramps - for want of a better term, e.g. where the hue and value of each symbol stays the same, but the saturation changes. I couldn't figure ...
- 700
1
vote
0
answers
631
views
What is the proper way to do an automatic rollback of a vector layer edit?
I'm trying to rollback automatically the changes in features of a in-memory vector layer that don't meet certain criteria.
The code I'm using for testing looks like this:
...
def some_function()
...
- 159
1
vote
0
answers
125
views
Adding dialog and classes to QGIS plugin [closed]
What are the steps to add files that represent a uidialog(draw with QTDesigner), and add the necessary python class files, using the default makefile provided with qgis plugin builder?
6
votes
1
answer
3k
views
Get extents of vector shape features in PyQGIS?
i am just wondering if it is possible to iterate through vector features and return the extent per feature without clipping the vector shape?
The code looks like this and comes from the PyQgis-...
- 8,180
9
votes
1
answer
2k
views
Listing installed QGIS plugins via PyQGIS
Can you please tell me how I can programmatically (or from the console) access the loaded plugin list? I tried:
QgsProviderRegistry.pluginList()
but got:
TypeError: QgsProviderRegistry.pluginList(...
- 221
4
votes
1
answer
3k
views
Creating Selection MapTool in PyQGIS Custom Application
I'm developing a custom GIS application using the PyQGIS API.
How can I let the user select features on the map using Maptools? I would like to replicate the select feature there in Qgis to make the ...
8
votes
1
answer
3k
views
Adding calculated fields with PyQGIS
In the Memory provider described in PyQGIS Cookbook and in the question Creating new empty vector layer with PyQGIS I can see how to create a Vector Layer programmatically using standard fields (...
- 159
2
votes
2
answers
4k
views
Cannot get changeAttributeValues() to work in a loop
I'm trying to use QGIS to loop through a set of points, find their elevation from a DEM and use that value to update the point layer's attribute table. The loop works fine until I try to use ...
- 7,873
7
votes
4
answers
11k
views
Linking to external files with relative path in QGIS actions
Objective: I have point layers with attributes that contain paths to external files (Visio, AutoCAD dwg...). I want to put them all in one folder together with the project file, compress the folder ...
- 2,024
27
votes
5
answers
25k
views
Getting path of project or layer file in PyQGIS
I am generating new raster files from vector layers on a project. I would like to save them in the same directory as the project or layer files.
How do I find this path using PyQGIS?
- 1,247
2
votes
0
answers
705
views
Qgis Plugin development with postgres data
can someone help me with initial developing on qgis plugin that displays postgres data table on a QTTableView or QTTableWidget?
So far:
I can connect to database using psycopg2 or using QtSql(tested ...
1
vote
0
answers
302
views
SVG markers with PyQGIS [closed]
How do you SVG-marker layers in PyQGIS? I'm importing a vector layer and want to display it with SVG-markers.
It seems that QgsSvgMarkerSymbolLayerV2 does not exist in PyQGIS...
- 41
11
votes
2
answers
11k
views
Getting projection from vector layer in QGIS
I am trying to set the projection on a raster to match that of a vector point layer. Thus I need to find out what is the projection of a given layer, to use it in the GDAL.Dataset.SetProjection() so ...
- 1,247
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
2
votes
0
answers
903
views
Accessing MySQL data from python built-in console of QGIS?
I'm writing a QGIS Plugin, and somewhere I want to present data from a MySQL database. It's simple data(strings,etc), not Geospatial, or vector data. I'm familiar with querying databases from python ...
2
votes
3
answers
2k
views
Merging large amount of polygon-features in script with GDAL/OGR Tools or Python?
We have a very large shapefile with over 30000 features and want to merge it with a script on a server. Currently we try it with QGIS, but the processing takes way too much time.
Is there a way to do ...
- 323
4
votes
1
answer
8k
views
Loading feature (.qml) styles from PyQGIS [duplicate]
I'm trying to set the styles for a vector layer by loading the .qml file in the python console. The qml-style file contains all categories and symbols needed, but I can not find the right function to ...
- 49
1
vote
0
answers
320
views
QGIS and embedded ajax (Bing Map) [closed]
I need to load in a docked QWebView this html:
< html >
< body >
< iframe width="100%" height="499" frameborder="0"
scrolling="no" ...
- 87
2
votes
1
answer
515
views
Is it possible to set a layer style (e.g. set the color ramp) before loading the layer using pyQGIS?
I am implementing a tool which allows an user to calculate some statistics with some data from the registration office. My question is, can I set some layer styles using pyQGIS?
The analysis part is ...
- 205
4
votes
1
answer
4k
views
Splitting geometry collection into its items using Python and QGIS API
I'm getting some geometries via intersecting lines by polygons (somewhat blindly - I don't really know if intersection exists and actually I don't need to know) using python and QGIS API: some_line....
- 5,621
18
votes
3
answers
17k
views
"Select by Attribute" in QGIS using python?
Is there a way to use the function "Select by Attribute" in QGIS using a python command? In my plugin the user should enter a value via a GUI and this value should be used in a function which selects ...
- 205
11
votes
3
answers
15k
views
Getting attributes of selected features using PyQGIS
Could anybody provide an example how to get the attributes of selected features?
I tried the following code in the Python Console : but I'm stuck at the point where I'd like to get the attributes:
...
- 261
3
votes
2
answers
6k
views
Setting color of feature depending on attributes with PyQGIS?
I'm trying to set the color of a vectorlayer feature depending on the feature attributes with PyQGIS.
How do you acces the attributes of a vectorlayer feature?
- 41
2
votes
1
answer
896
views
Is there an itemSelectionChanged Signal in Attribute Table?
The QgsVectorLayer class emits a selectionChanged() signal . If a QGIS user for example selects a record in the Attribute Table of a Vector Layer - a selectionChanged() signal is emitted an can be ...
- 75
5
votes
1
answer
4k
views
How to find all intersections and count lines arriving at each intersection?
I'm having a hard time getting off the ground with this, and am trying to move away from ArcGIS / arcpy.
I have a shapefile with a network of polylines. I want to find/count all 2-way intersections, ...
- 280
2
votes
1
answer
4k
views
Implementing signals on add or modify feature using PyQGIS
I've created a test plug-in in QGIS successfully but have had a hard time implementing a signal on a vector layer event (add or modify feature). I've added this to my initGUI method:
QObject.connect(...
- 29
11
votes
3
answers
19k
views
Obtaining the data of one selected feature in QGIS using Python? [closed]
Is it possible to get the data of one selected feature in QGIS using Python, and if so how?
In my example I have a layer which shows some parcels for urban planning. If I now select one of the parcels ...
- 822
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
14
votes
2
answers
5k
views
Adding toolbar via PyQGIS?
Through tutorials I learned how to add a toolbutton to the plugins-toolbar via python. Now I wonder how to add a complete toolbar with toolbarbuttons via python.
Can anybody give some example-code?
- 261
3
votes
0
answers
751
views
no module named core
I am trying to access and use QGIS modules/class/methods from IDLE on a mac. I have had the same problem as a few other people, and browsing the forums have tried to follow the advice they have been ...
- 637
31
votes
3
answers
29k
views
Creating new empty vector layer with PyQGIS
I have looked at a few tutorials on Python scripts for QGIS. All of them create new vector and raster layers with some existing data source e.g. shapefile or GeoTIFF or PostGIS database table.
Is it ...
4
votes
1
answer
3k
views
legend groups and layer position/order qgis 1.8
I'm tring to programmatically create layer sequence also using groups.
Simple python code:
layer = QgsVectorLayer("004cp000.shp", "004cp000", "ogr")
QgsMapLayerRegistry.instance().addMapLayer(layer)
...
- 41
4
votes
0
answers
2k
views
Changing feature's geometry?
I'm creating my layer like this:
crs = core.QgsCoordinateReferenceSystem(4326, core.QgsCoordinateReferenceSystem.EpsgCrsId)
uri = "Polygon"
uri += '?crs=' + crs.authid()
uri += '&field=id_tsk:...
- 285
1
vote
1
answer
1k
views
Is getting wrong attribute values from a feature in qgis
I make two polylines features(in my example both consists of two points) with the add feature tool. Then I (with code) add some attribute values on the first feature, then changes the geometry of the ...
- 31
1
vote
1
answer
89
views
Which class to work with vector layers using PyQGIS?
I'm doing different operations on vector layers.
Which class should I use for vector layer i.e QgsVectorLayer or QgsVectorLayerDataProvider?
- 19
2
votes
1
answer
2k
views
Importing QGIS core into Python on OSX
I am interested in learning how to write standalone scripts using QGIS. An answer to my previous question directed me to the PyGIS CookBook which has the following instructions for importing the ...
- 16.3k