To get the most out of this book

Before going further into this book, you will want to install latest versions of PostgreSQL and PostGIS (9.6 or 103 and 2.3 or 2.41, respectively). You may also want to install pgAdmin (1.18) if you prefer a graphical SQL tool. For most computing environments (Windows, Linux, macOS X), installers and packages include all required dependencies of PostGIS. The minimum required dependencies for PostGIS are PROJ.4, GEOS, libjson and GDAL.
A basic understanding of the SQL language is required to understand and adapt the code found in this book's recipes.

Download the example code files

You can download the example code files for this book from your account at www.packtpub.com. If you purchased this book elsewhere, you can visit www.packtpub.com/support and register to have the files emailed directly to you.

You can download the code files by following these steps:

1. Log in or register at www.packtpub.com.
2. Select the SUPPORT tab.
3. Click on Code Downloads & Errata.
4. Enter the name of the book in the Search box and follow the onscreen instructions.

Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:

• WinRAR/7-Zip for Windows
• Zipeg/iZip/UnRarX for Mac
• 7-Zip/PeaZip for Linux

The code bundle for the book is also hosted on GitHub at https://github.com/PacktPublishing/PostGIS-Cookbook-Second-Edition. In case there's an update to the code, it will be updated on the existing GitHub repository.

We also have other code bundles from our rich catalog of books and videos available at https://github.com/PacktPublishing/. Check them out!

Download the color images

We also provide a PDF file that has color images of the screenshots/diagrams used in this book. You can download it here: https://www.packtpub.com/sites/default/files/downloads/PostGISCookbookSecondEdition_ColorImages.pdf.

Conventions used

There are a number of text conventions used throughout this book.

CodeInText: Indicates code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles. Here is an example: "We will import the firenews.csv file that stores a series of web news collected from various RSS feeds."

A block of code is set as follows:

SELECT ROUND(SUM(chp02.proportional_sum(ST_Transform(a.geom,3734), b.geom, b.pop))) AS population 
  FROM nc_walkzone AS a, census_viewpolygon as b
  WHERE ST_Intersects(ST_Transform(a.geom, 3734), b.geom)
  GROUP BY a.id;

When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:

SELECT ROUND(SUM(chp02.proportional_sum(ST_Transform(a.geom,3734), b.geom, b.pop))) AS population 
  FROM nc_walkzone AS a, census_viewpolygon as b
  WHERE ST_Intersects(ST_Transform(a.geom, 3734), b.geom)
  GROUP BY a.id;

Any command-line input or output is written as follows:

> raster2pgsql -s 4322 -t 100x100 -F -I -C -Y C:\postgis_cookbook\data\chap5\PRISM\us_tmin_2012.*.asc chap5.prism | psql -d postgis_cookbook

Bold: Indicates a new term, an important word, or words that you see onscreen. For example, words in menus or dialog boxes appear in the text like this. Here is an example: "Clicking the Next button moves you to the next screen."

Warnings or important notes appear like this.

Tips and tricks appear like this.