Tagged Questions

Python bindings for QGIS.

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1
vote
0answers
71 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() ...
3
votes
1answer
616 views

Get extents of vector shape features in python

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 ...
3
votes
1answer
522 views

Creating Selection MapTool in PyQgis Custom Application

I'm developing a custom GIS application using 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 ...
1
vote
1answer
190 views

Is there any python function to rotate map layers?

Is there any python function allowing a user to rotate map layers in the map canvas. If so, could you please point this out for me? I want to rotate a map layer, using a factor of rotation in ...
3
votes
1answer
367 views

Is it possible to programmatically add calculated fields?

In the Memory provider described in PyQGIS Cookbook or in question How to create a new empty vector layer programmatically? I can see how to create a vector layer programmatically using standard ...
1
vote
2answers
398 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 ...
4
votes
2answers
981 views

How do I get the path of a 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
vote
0answers
289 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 ...
1
vote
0answers
71 views

SVG markers with PyQGIS

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...
1
vote
1answer
707 views

how to get the projection from a vectorlayer in qgis?

Hi I am trying to set the projection on a raster to match that of a vector point layer. Thus I need to findout what is the projection of a give layer, to use it in the GDAL.Dataset.SetProjection() so ...
4
votes
1answer
520 views

How to Create a raster layer from a 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 ...
3
votes
1answer
2k views

QGIS: How to load feature (.qml) styles from python? [duplicate]

Possible Duplicate: How to style a layer from console? 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 ...
2
votes
1answer
256 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 ...
2
votes
1answer
704 views

How to split 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: ...
3
votes
1answer
1k views

pyqgis: How to get features of selected geometries

I wonder if anybody could provide an example how to get the attributes of selected Features? I tried the folowing Code in the python Console - but I'm stuck at the point where I'd like to get the ...
2
votes
1answer
137 views

Color depending on attribute

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?
2
votes
1answer
270 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 ...
4
votes
1answer
1k 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, ...
5
votes
1answer
2k views

How can i obtain the data of one selected feature in QGIS using python?

I have a problem / question regarding python and QGIS. Is it, and yes how, possible to get the data of one selected feature in QGIS using python? In my example I have a layer which shows some parcels ...
9
votes
1answer
2k 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 = ...
8
votes
1answer
938 views

How to add a toolbar via python?

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? ...
1
vote
0answers
226 views

no module named core

Hi 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 ...
0
votes
0answers
154 views

How to build QGIS with Python on Redhat?

I'm attempting to run QGIS on Redhat 5 64 bit architecture. Version of Python is 2.4.3. Version of QGIS is 1.7.4 (wroclaw). When I run qgis, the splash screen appears, followed by a QMessageBox that ...
12
votes
2answers
4k views

How to create a new empty vector layer programmatically?

I am new to python and QGIS. I have looked at a few tutorials of python scripts for QGIS. All of them create new vector and raster layers with some existing data source. eg. shapefile or geotiff or ...
2
votes
0answers
904 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) ...
1
vote
0answers
592 views

How to change feature's geometry?

Hy, I'm creating my layer like this: crs = core.QgsCoordinateReferenceSystem(4326, core.QgsCoordinateReferenceSystem.EpsgCrsId) uri = "Polygon" uri += '?crs=' + crs.authid() uri += ...
0
votes
1answer
711 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 ...
2
votes
1answer
72 views

Which class should I use to work with vector layers?

I'm doing different operations on vector layers. Kindly suggest which class should I use for vector layer i.e QgsVectorLayer or QgsVectorLayerDataProvider.
1
vote
1answer
496 views

How to get a signal when the geometry to a line in QGIS is changed

I am working on a plugin in QGIS and want to get a signal when the geometry to a feature(in this case a polyline) in my layer is changed. For example if I use the node tool to drag one of the nodes. ...
1
vote
0answers
34 views

qgis.core error [duplicate]

Possible Duplicate: qgis.core import error I am new in quantum gis and python, I installed quantum gis 1.8 from osgeo4w installer, after I installed python 2.7 and started python shell and ...
4
votes
3answers
373 views

How do I specify the position, style and units of the ScaleBar in pyqgis?

I would like to add a scale bar to my composition using the python console and then export it to a raster image. I am following the MapRendering tutorial with the "output using map composer " approach ...
2
votes
1answer
501 views

How to load a postgres view using pyQgis?

Under Qgis 1.8 on Windows 7 I have this problem with my pyArchInit plugin: I need to load on the map canvas my geometries from a postgis layer. Till the 1.7.4 version I use the method explained on the ...
8
votes
4answers
1k views

How to run sextante algorithms outside of qgis python console?

I'm kind of stuck trying to figure out the way to run sextante from a standalone python from OSGeo4W distribution. The reason I want to do this is that I got tired entering parameters in the dialog ...
2
votes
1answer
764 views

qgis.core import error

I would want to use the Qgis api for custom desktop application. When I imported the qgis.core module, I get the following error >>> import qgis.core Traceback (most recent call last): ...
2
votes
1answer
252 views

QGIS Updating composer label text via python - problem with Item Properties panel

I am writing a plugin that replaces the text of a composer label based on its itemID. When I change the text of the label using: item.setText("Hello World") the label changes on the composer but ...
1
vote
2answers
1k views

Problem loading vector layer (pyQGIS)

I've installed the qgis on ubuntu 12.04 following the instructions on http://hub.qgis.org/projects/quantum-gis/wiki/Download. I am trying to test the Python API and try to do the follwoing from ...
2
votes
1answer
234 views

How can i include program form (created in Designer ) to my QGIS plugin?

How can I include a form created in Designer in my QGIS plugin? And how to get controls values (textbox,label,etc)?
3
votes
1answer
1k views

How can I add button to the QGIS toolbox or create my own toolbox?

I want to create a button and add it to the QGIS toolbox or alternatively create my own toolbox and add the button here. A plugin should be started when the user clicks the button.
2
votes
1answer
221 views

Can't load PYQGIS

I get this error; any comments Couldn't load PyQGIS. Python support will be disabled. Traceback (most recent call last): File "", line 1, in ImportError: ...
3
votes
2answers
2k views

How can I specify the CRS of a raster layer in pyqgis?

I manipulating netcdf raster data from the QGIS python console. The metadata of my netcdf file does not provide the Reference system. However I know it is 'EPSG:4326' I am writing a python script to ...
3
votes
1answer
670 views

Changing attribute data types using PyQGIS

OK, so I've already asked a question how to access attribute data types when developing plugin for QGIS, using PyQGIS. And one helpful member said i should use pendingFields() method on the current ...
3
votes
1answer
150 views

How to display a particular area?

Hy, I'm developing a plugin in python for Qgis. I would like the user to select a particular area in a list (let say a country list) and zoom in the map on the corresponding area. Actually I'm ...
3
votes
1answer
1k views

How to use gdal_contour in QGIS Python console?

Is there a way to use the gdal_contour utility with-in the python console of qgis ? Thank you
6
votes
1answer
1k 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 ...
2
votes
2answers
2k views

How to access attribute data type in QGIS?

I've been developing a plugin on 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, plugin displays ...
2
votes
1answer
308 views

How to connect QGIS to a WMS-C with python?

I would like to connect my QGis to a WMS-C server when my python plugin load. How can I do that ? BTW, the method: addRasterLayer do not seams to handle WMS-C layer...
4
votes
2answers
675 views

How can I add OpenLayers layer from the python console?

I am new to the python console. How can I add a layer from the OpenLayers plugin from the python console? Thank you
2
votes
1answer
477 views

How to display local file's geometries as rubber bands in QGIS

I'd like to get geometries from a local file (e.g. GML) displayed as rubber bands (QgsRubberBands) in QGIS. However, I wouldn't like to load the layer into the map because in the real scenario there ...
3
votes
1answer
846 views

Get a pixel value

How can i do this operation: I want to get a pixel value fro the satellite image (Landat, GeoTIFF, 7 bands) using qgis-python. What operators should i use? (for example in qgis's Python Console) ...
1
vote
1answer
574 views

How to translate ESRI cursor example to pyQgis?

For example, how to translate this code into pyqgis? rows = gp.UpdateCursor("D:/St_Johns/data.mdb/roads") row = rows.Next() while row: row.buffer_distance = row.road_type * 100 ...