QGIS Python

QGIS is a powerful programming application, that allows you to extend the core functionality of the software, as well as write scripts to automate your tasks.

QGIS 0.9 was the first support Python scripting language. There are several ways to use Python in QGIS Desktop:

Create and use plugins
Issue commands in the Python console
Automatically run Python code when Q-GIS starts
Create processing algorithms
Create functions for expressions in QGIS
Create custom applications based on the QGIS API

Use the Python API to let the user interact with its objects, like; layers, feature or interface.

Tutorial Contents

Main Tools in QGIS for Python

Tool	Description
Python Console	Built-in terminal for writing Python commands directly
PyQGIS API	Python API to interact with objects (layers, maps, geometries, etc.)
Processing Toolbox	Run and script geoprocessing tools using Python
Plugins	Create or use Python-based plugins

QGIS Python Console

The Python console main features are:

Python
PyQGIS
PyQt4
QScintilla2
osgeo-gdal-ogr

Open Console

To open the console, go to Plugins > Python Console

Console Toolbar

Clear console
Import class
Run command
Show editor
Options
Help

Console Setting

You are already open Python Console panel, click Options tab.

Now the Python Console Setting window appear, show three options is available:

Console
Editor
API

Examples

1. Load a shapefile:

iface.addVectorLayer('/path/to/file.shp', 'My Layer', 'ogr')

1. Create a buffer:

import processing
processing.run("native:buffer", {
    'INPUT': 'my_layer',
    'DISTANCE': 1000,
    'OUTPUT': 'memory:buffered'
})

1. Save a layer to GeoPackage:

QgsVectorFileWriter.writeAsVectorFormat(layer, '/path/out.gpkg', 'UTF-8', layer.crs(), 'GPKG')

1. Print all layer names:

for layer in QgsProject.instance().mapLayers().values():
    print(layer.name())

PyQGIS Developer Cookbook

Scripting in the Python Console

Python API Documentation

Q-GIS Python API documentation project