QGIS Python Programming Cookbook

coverpage

QGIS Python Programming Cookbook

Credits

About the Author

About the Reviewers

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Preface

What this book covers

What you need for this book

Who this book is for

Sections

Conventions

Reader feedback

Customer support

Chapter 1. Automating QGIS

Introduction

Installing QGIS for development

Using the QGIS Python console for interactive control

Using the Python ScriptRunner plugin

Setting up your QGIS IDE

Debugging QGIS Python scripts

Navigating the PyQGIS API

Creating a QGIS plugin

Distributing a plugin

Creating a standalone application

Storing and reading global preferences

Storing and reading project preferences

Accessing the script path from within your script

Chapter 2. Querying Vector Data

Introduction

Loading a vector layer from a file sample

Loading a vector layer from a spatial database

Examining vector layer features

Examining vector layer attributes

Filtering a layer by geometry

Filtering a layer by attributes

Buffering a feature intermediate

Measuring the distance between two points

Measuring the distance along a line sample

Calculating the area of a polygon

Creating a spatial index

Calculating the bearing of a line

Loading data from a spreadsheet

Chapter 3. Editing Vector Data

Introduction

Creating a vector layer in memory

Adding a point feature to a vector layer

Adding a line feature to a vector layer

Adding a polygon feature to a vector layer

Adding a set of attributes to a vector layer

Adding a field to a vector layer

Joining a shapefile attribute table to a CSV file

Moving vector layer geometry

Changing a vector layer feature's attribute

Deleting a vector layer feature

Deleting a vector layer attribute

Reprojecting a vector layer

Converting a shapefile to KML

Merging shapefiles

Splitting a shapefile

Generalizing a vector layer

Dissolving vector shapes

Performing a union on vector shapes

Rasterizing a vector layer

Chapter 4. Using Raster Data

Introduction

Loading a raster layer

Getting the cell size of a raster layer

Obtaining the width and height of a raster

Counting raster bands

Swapping raster bands

Querying the value of a raster at a specified point

Reprojecting a raster

Creating an elevation hillshade

Creating vector contours from elevation data

Sampling a raster dataset using a regular grid

Adding elevation data to line vertices using a digital elevation model

Creating a common extent for rasters

Resampling raster resolution

Counting the unique values in a raster

Mosaicing rasters

Converting a TIFF image to a JPEG image

Creating pyramids for a raster

Converting a pixel location to a map coordinate

Converting a map coordinate to a pixel location

Creating a KML image overlay for a raster

Classifying a raster

Converting a raster to a vector

Georeferencing a raster from control points

Clipping a raster using a shapefile

Chapter 5. Creating Dynamic Maps

Introduction

Accessing the map canvas

Changing the map units

Iterating over layers

Symbolizing a vector layer

Rendering a single band raster using a color ramp algorithm

Creating a complex vector layer symbol

Using icons as vector layer symbols