Book Image

Python Geospatial Development - Third Edition

By : Erik Westra
Book Image

Python Geospatial Development - Third Edition

By: Erik Westra

Overview of this book

Geospatial development links your data to locations on the surface of the Earth. Writing geospatial programs involves tasks such as grouping data by location, storing and analyzing large amounts of spatial information, performing complex geospatial calculations, and drawing colorful interactive maps. In order to do this well, you’ll need appropriate tools and techniques, as well as a thorough understanding of geospatial concepts such as map projections, datums, and coordinate systems. This book provides an overview of the major geospatial concepts, data sources, and toolkits. It starts by showing you how to store and access spatial data using Python, how to perform a range of spatial calculations, and how to store spatial data in a database. Further on, the book teaches you how to build your own slippy map interface within a web application, and finishes with the detailed construction of a geospatial data editor using the GeoDjango framework. By the end of this book, you will be able to confidently use Python to write your own geospatial applications ranging from quick, one-off utilities to sophisticated web-based applications using maps and other geospatial data.
Table of Contents (20 chapters)
Python Geospatial Development Third Edition
Credits
About the Author
About the Reviewer
www.PacktPub.com
Preface
Index

Exporting shapefiles


We next need to implement the ability to export a shapefile. The process of exporting a shapefile is basically the reverse of the importing logic, and involves the following steps:

  1. Create an OGR shapefile to receive the exported data.

  2. Save the features and their attributes into the shapefile.

  3. Compress the shapefile into a ZIP archive.

  4. Delete our temporary files.

  5. Send the ZIP file back to the user's web browser.

All this work will take place in the shapefileIO.py module, with help from some utils.py functions. Before we begin, let's define the export_data() function so that we have somewhere to place our code. Edit shapefileIO.py, and add the following new function:

def export_data(shapefile):
    return "More to come..."

While we're at it, let's create the "Export Shapefile" view function. This will call the export_data() function to do all the work. Edit the shapefiles/views.py file and add the following new function:

def export_shapefile(request, shapefile_id):
  try:
    shapefile...