Book Image

QGIS Python Programming Cookbook

Book Image

QGIS Python Programming Cookbook

Overview of this book

Table of Contents (16 chapters)
QGIS Python Programming Cookbook
About the Author
About the Reviewers

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

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:

  1. First, we load the layer:

    lyr = QgsVectorLayer("/Users/joellawhead/qgis_data/census/GIS_CensusTract_poly.shp", "Census", "ogr")
  2. Next, we toggle scale-based visibility:

  3. Then, we set the minimum and maximum map scales at which...