Book Image

QGIS 2 Cookbook

By : Alex Mandel, Víctor Olaya Ferrero, Anita Graser, Alexander Bruy
Book Image

QGIS 2 Cookbook

By: Alex Mandel, Víctor Olaya Ferrero, Anita Graser, Alexander Bruy

Overview of this book

QGIS is a user-friendly, cross-platform desktop geographic information system used to make maps and analyze spatial data. QGIS allows users to understand, question, interpret, and visualize spatial data in many ways that reveal relationships, patterns, and trends in the form of maps. This book is a collection of simple to advanced techniques that are needed in everyday geospatial work, and shows how to accomplish them with QGIS. You will begin by understanding the different types of data management techniques, as well as how data exploration works. You will then learn how to perform classic vector and raster analysis with QGIS, apart from creating time-based visualizations. Finally, you will learn how to create interactive and visually appealing maps with custom cartography. By the end of this book, you will have all the necessary knowledge to handle spatial data management, exploration, and visualization tasks in QGIS.
Table of Contents (19 chapters)
QGIS 2 Cookbook
About the Authors
About the Reviewers

Calculating the shortest paths with the QGIS network analysis library

As mentioned in the recipe, Calculating the shortest paths using the Road graph plugin, QGIS comes with a network analysis library, which can be used from the Python console, inside plugins, to process scripts, and basically anything else that you can think of. In this recipe, we will introduce the usage of the network analysis to compute the shortest paths in the Python console.

Getting ready

To follow this recipe, load network_pgr.shp from the sample data.

How to do it…

Instead of typing or copying the following script directly in the Python console, we recommend opening the Python console editor using the Show editor button on the left-hand side of the Python console:

  1. Paste the following script into the editor:

    import processing
    from import VectorWriter
    from PyQt4.QtCore import *
    from qgis.core import *
    from qgis.networkanalysis import *
    # create the graph
    layer = processing.getObject('network_pgr...