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

Building DateTime strings

Date and time data get stored in all sorts of ways. One of the more frustrating issues is that some common GIS formats (Shapefiles) can't store date and time in the same field without making it a string. This is fine for visual display but terrible for use with tools that use DateTime for their functionality, such as the TimeManager Plugin (refer to Chapter 4, Data Exploration).

Getting ready

Use datetime-example.shp, which contains a variety of date and time representations to play with.

How to do it…

  1. Load datetime-example.shp.

  2. Open the attribute table of datetime-example.

  3. Create a new field. As this is a shapefile, we'll need to use a String of length 30 (or you can use the empty field called calculated).

  4. Turn on layer editing (this is the pencil icon, which is the first icon to the left of the window toolbar).

  5. From the drop-down list, select Calculated.

  6. Now press the Calculation button.


    In older versions of QGIS, you'll need to open the Field calculator, which also...