Python bindings for QGIS.

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Cannot load postgis layer from sql string in pyqgis

I'm trying to load a layer using the following code in qgis python console: sql = "(select the_geom, ID from mytable)" uri = QgsDataSourceURI() ...
2
votes
1answer
27 views

How to store a password during one QGIS work session?

I'd like to get into qgis-plugin development, but am rather new to both python and QGIS development. I intend to write a plugin which connects data from a mysql database to shapefiles. As the data is ...
3
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2answers
224 views

Load and display a layer using PYQGIS

I'm having a go at using pyqgis from within the QGIS python console to load a layer from SQL Server and display it. I feel like I'm part way there but I'm having a real issue getting the layer to ...
2
votes
1answer
241 views

pyQgis in stand alone script, vector loading error

I am trying to use the Qgis functions in a stand alone Python script. I m running Mountain Lion OS, 2.7 Python & the Qgis 2.0.1 Dufour. My main problem is that I cannot get started - I cannot ...
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1answer
16 views

How to delete selected features in Qgis using Python

I have a shape file with only one field DN. I would like to delete all features which does not have specific value of the field. Let say the DN can be 1,2 or 3. So far I was able to find out how to ...
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1answer
22 views

QGIS Python console - save image from bounding box

I want to save an image from QGIS but the save image functionality feels limited. My question is if it's possible to use the python command line to save an image at a specific zoomed in scale and to ...
1
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1answer
23 views

pyQGIS - Data Source is Invalid

Why I am getting Data Source is Invalid in python console of QGIS when running: vlayer = QgsVectorLayer("home/sanjayr/Desktop/india-latest.shp/buildings.shp","sanjay","ogr") I am using QGIS 2.4 on ...
2
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0answers
30 views

Performing buffering and intersection with script in PyQGIS

I wrote a script that performs the intersection of two layers: The first Layer -> layer1, represents the rivers The second Layer -> layer2, represents a set of circular dots distributed in a ...
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0answers
28 views

Clipping between features within a single vector?

Is it possible (via the Qgis API and friends), to clip polygonal features within a single vector layer? The hope is to accomplish this without having to duplicate the feature into a new layer. ...
1
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1answer
45 views

QGIS 2.4 plugin PyQT qWebview javascript interface problem

I have a QGIS plugin which contains a qtwebview and Javascript communication between the page and the plugin. It is working perfectly with QGIS 2.2 but not with 2.4 (both QGIS versions share the ...
4
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1answer
58 views

QGIS Processing Progress

I have been developing a python plugin that uses Processing algorithm for raster calculations. I want to support the gui with progress bar. How can i connect Processing job to progress bar? I found ...
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0answers
35 views

Using two different Python versions for QGIS scripting?

I´m intending to learn scripting with python in QGIS, but I have a couple of questions. I'm using Python 3.4 for learning which is installed in my laptop, but QGIS is using Python2.7 How could I ...
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1answer
235 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 ...
3
votes
1answer
835 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 ...
1
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1answer
76 views

Why is feature.geometry() None in my user-defined expression function?

I'm trying the user-defined expression functions for QGIS, as listed on Nathans blog: http://nathanw.net/2012/11/10/user-defined-expression-functions-for-qgis/ I always get the feature.geometry() as ...
1
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1answer
104 views

How can I add grid lines to a print composition using pyqgis?

I'm writing a qgis plugin to create an image in the print composer of the current map. I can get the map rendered in the proper place with a frame of the right width, and I can get grid annotations ...
0
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1answer
64 views

Get Index for a group QGIS Python

I am trying to add new layers into a specific group which I can get to work if I know the index but how can I get python to fid the index of a group so it can load the new layer into the group ...
2
votes
1answer
19 views

QGIS Processing - Additional Creation Parameter for GdalWarp

I am having a hard time getting the "Additional Creation Parameters" to work when using GdalWarp through the processing toolbox. I am trying to set the nodata value to 0 for the output raster. ...
0
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1answer
40 views

How I can get coordinates by clicking on the QGis Canvas with PyQGIS?

Is there are any procedure on QgsMapCanvas (pyqgis, qgis) in order to obtain a pair of coordinates by clicking on the map canvas? Are there any python code I can see?
2
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1answer
42 views

PyQGIS - Start/Stop Editing with data Provider - Commiting changes

I want to edit a specific field for a QgsVectorLayer, within a QGIS application. I am facing inconsistent results from my code, ie: changes are not alway commited. Please could someone point me to ...
2
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2answers
138 views

Is there a function to select a region of a map for further processing with Python?

I would like to select a map's region in QGIS for further processing with python console. Ideally I would like to select the region with a mouse drag (like Gimp crop function) and then e.g. analyze ...
1
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1answer
49 views

QgsMapRenderer to export current extent using PyQGIS

I am trying to accomplish PyQGIS simple map rendering via the QGIS 2.0 Python console, but end up with only a blank image. I've followed instructions of this link. My objective is to export a simple ...
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2answers
162 views

QGIS 2.4: plugin changes map tool canvas click behavior from 2.0

I had created a plugin for QGIS 2.0 to add new features more easily. It involves changing extents and updating snapping options along with triggering the default actionAddFeature(). However, I've ...
4
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1answer
147 views

How can I modify layer order with the QGIS python API

Typically, after a new_layer = addRasterLayer(...) that inserts new_layer before the active layer, I'd like to move it to the top of the table of contents. How to do it? I use an existing QGIS ...
4
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2answers
315 views

How to write scripts that can call on both Arcpy and PyQGIS?

I have spent quite a bit of time looking for a clear answer this topic and have still been unable to really accomplish my goal of accessing PyQGIS in a stand alone script. Parts of answers have been ...
2
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0answers
20 views

Refreshing “layer render order” widget

i made changes in the render order of my map canvas using a : qgis.utils.iface.mapCanvas().setLayerSet(a) "a" being a list of QgsMapCanvasLayer My code is working as expected (i see result on map ...
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1answer
46 views

Programmatically export a Qgis project

I have a QGis project that I programmatically modify using the Python xml.etree library. Now, I would like to know if it is possible to add few lines to my script in order to export the modified ...
3
votes
1answer
37 views

Changing attribute values in a memory layer

I'm trying to change attribute values in a memory layer. My memory layer is defined in this way: pro.addAttributes([QgsField("nom", QVariant.String), QgsField("valeur", QVariant.Int)]) I made ...
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4answers
1k views

How to get features based on their attributes using Python?

How to Get features by their attributes (similar to Iqueryfilter in arcobjects) in Qgis using python? Instead of getting all features and filter it manually, is there any option to use whereclause to ...
1
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1answer
125 views

How to save after using fet.setFeatureId in pyQGIS?

By using the following code, I want to change the id of the line when saving the line. But the setFeatureId command, gives a false when doing the commitChanges(). Any idea how to change the id? vl = ...
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0answers
29 views

Retrieve a point coordinates from map canvas using QGIS API

I'm trying to build a plugin that firstly captures the map coordinates. I have tried to adapt the map tool explained in this post: How to programatically check for a mouse click in QGIS The code I ...
0
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2answers
431 views

How to display data from a feature?

I want to display data based on the feature currently selected/clicked on. I am following a tutorial from http://www.qgisworkshop.org/html/workshop/plugins_tutorial.html. It initially shows you how ...
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0answers
24 views

Memory layer or QgsVectorFileWriter Error?

Currently this excerpt of code will not save to file (as it is supposed to). The memory layer is visable and editable. Yet even when manually saving the layer, any priorly added features ...
2
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1answer
27 views

QgsMapCanvas.reresh() does not reload new wfs layer features, but panning does

I have a wfs layer loaded in a standalone QGIS app, which I am updating by running a database query on the view it is based on. The feature is added with no problems and I reload the layer with: # ...
2
votes
1answer
522 views

How to debug 'Layer is not valid error' from Python plugin?

I'm trying to understand what goes wrong with a QGIS python plugin. Basically I'm trying to render a series of POINT. The query works fine, at least giving it by hand from inside PostGIS DB: "SELECT ...
1
vote
1answer
480 views

QGis 2.0.1 mapserver extension missing

I tried to export my Qgis projects to mapserver, using RT mapserver extension, because there is not any other extension in my version of QGis.(QGis 2.0.1 Dufour on ubuntu 12.04 LTS). After installing ...
1
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1answer
19 views

How to set QGIS options in standalone pyqgis application

I have a standalone application which uses the QGS api to view and query map layers. One layer is a WMS-C layer which automatically caches tiles which is great. I want to also activate a setting which ...
1
vote
1answer
37 views

Import shapefile is not working in pyshp?

I am just trying to use "pyshp" package to open shapefile in Python and use the Attribute data for further development. Firstly I have downloaded pyshp package for python 2.7 and installed it in my ...
3
votes
1answer
35 views

PyQGIS esri ascii grid to .bil conversion

Esri ASCII GRID can be converted to esri .bil format by following way in a desktop From QGIS desktop menu-->Raster-->conversion-->Translate(convert format) How can I write a python code because I have ...
2
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0answers
20 views

access point layer representation in qgis with pyqgis

I am exporting the style of a categorized point layer with qgis: unfortunately my code only extract the size of the symbol in the definition of the properties of the layer but not the ...
3
votes
1answer
174 views

How to create a line layer which connects a point layer to a line layer?

In the map shown below, I have manually created the dummy lines (in green). Using python, and without using PostGIS or sextante, I would like to automate the creation of these dummy links between a ...
3
votes
1answer
33 views

Why is the SelectionChanged signal triggered every time i click on the layer?

i'm making some experiments with the SelectionChanged signal of a QgsVectorLayer. i try this piece of code : curLayer.selectionChanged.connect(self.test) and "test" print a warning message. The ...
4
votes
1answer
302 views

QGis Zonal Statistics Plugin NoData included in Calculations

I have been trying to use the QGIS zonal statistics plugin. My raster has a nodata value of -99999 and all other values are positive. After computing the mean zonal statistics there are a number of ...
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2answers
53 views

Pyqgis 2.2 : zoom to layer extent?

Regarding my plugin pyqgis 2.2, i can load a vector layer succesfully. But when i try to zoom to the layer extent it does not work. How to do in order to zoom to the layer extent? Thank you very ...
1
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0answers
19 views

PyQGIS standalone gdal_ECW_JP2ECW.dll error

This is my code in a batch file My error messages are gdal_ECW_JP2ECW.dll error unable to open EPSG support file gcs.csv Thanks in advance REM Change OSGEO4W_ROOT to point to the base install folder ...
0
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1answer
95 views

How to clip a raster by a shapefile in pyqgis?

Currently I am working with some satellite images (grib files) in pygis. As I want to work only with the cells in my study area, i need to clip the raster by a shapefile. I know í can do this by ...
0
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1answer
49 views

How to delete column/field in PyQGIS?

How to remove or delete column fields in a shape file using python?
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0answers
39 views

How to add a TIF raster layer programmatically?

This is my code whenever i try to load .tif image it shows layer is not valid,QgsRasterLayer always return invalid layer (I am using linux 12.04). QString myFileName = ...
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0answers
6 views

Pyqgis 2.2 : get signal on feature added : error message

For my pyqgis plugin 2.2, I try to: def logFeatureAdded(self,layerId,addfeatures): message = str(layerId) + " has features added: " for feature in addedFeatures: message += str( ...
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0answers
32 views

Get signal on edited feature?

Regarding my pyqgis plugin 2.2 , I've implemented signal on a vector layer event successfully. For instance, whenever i create a new feature, i can read a new basic message appeared via QGIS logging ...