You're reading from QGIS Python Programming Cookbook, Second Edition Automating geospatial development

Product type Paperback

Published in Mar 2017

Publisher Packt

ISBN-13 9781787124837

Length 464 pages

Edition 2nd Edition

Languages

Python

Tools

Eclipse

Concepts

Geospatial Analysis

Author (1):

Joel Lawhead

View More author details

Table of Contents (10) Chapters

Preface

1. Automating QGIS FREE CHAPTER

2. Querying Vector Data

3. Editing Vector Data

4. Using Raster Data

5. Creating Dynamic Maps

6. Composing Static Maps

7. Interacting with the User

8. QGIS Workflows

9. Other Tips and Tricks

Setting scale-based visibility for a layer

Sometimes, a GIS layer only makes sense when it is displayed at a certain scale, for example, a complex road network. PyQGIS supports scale-based visibility to programmatically set the scale range, in which a layer is displayed. In this recipe, we'll investigate scale-dependent layers.

Getting ready

You will need the sample census tract shapefile, available as a ZIP file from https://github.com/GeospatialPython/Learn/raw/master/GIS_CensusTract.zip.

Extract the zipped layer to a directory named census in your qgis_data directory.

How to do it...

We will load the vector layer, toggle scale-based visibility, set the visibility range, and then add the layer to the map. To do this, perform the following steps:

First, we load the layer:

        lyr = QgsVectorLayer("/qgis_data/census/GIS_CensusTract_poly.shp",
                             "Census", "ogr")

Next, we toggle scale-based visibility:

        lyr.toggleScaleBasedVisibility...

The rest of the chapter is locked

Tech Concepts

Programming languages

Tech Tools

Unlimited access to the largest independent learning library in tech of over 8,000 expert-authored tech books and videos.

Innovative learning tools, including AI book assistants, code context explainers, and text-to-speech.

50+ new titles added per month and exclusive early access to books as they are being written.

A free Packt account unlocks extra newsletters, articles, discounted offers, and much more. Start advancing your knowledge today.

Unlock this book and the full library FREE for 7 days

Get unlimited access to 7000+ expert-authored eBooks and videos courses covering every tech area you can think of

Start free trial

Renews at €18.99/month. Cancel anytime

Authors (1)

Joel Lawhead

Joel Lawhead is a PMI-certified Project Management Professional (PMP), a certified GIS Professional (GISP), and vice president of NVision Solutions, Inc., an award-winning firm specializing in geospatial technology integration and sensor engineering for NASA, FEMA, NOAA, the US Navy, and many other commercial and non-profit organizations. Joel began using Python in 1997 and started combining it with geospatial software development in 2000. He has authored multiple editions of Learning Geospatial Analysis with Python and QGIS Python Programming Cookbook, both from Packt. He is also the developer of the open source Python Shapefile Library (PyShp) and maintains a geospatial technical blog.

See other products by Joel Lawhead