Adding a scale bar to a map
A scale bar is one of the most important elements of a map composition, as it defines the scale of the map to determine the ground distance on the map. The QGIS composer allows you to create several different types of scale bars from a simple text scale ratio to a graphical, double bar scale bar with two measurement systems. In this recipe, we'll create a scale bar that increments in kilometers.
Getting ready
You will need to download the following zipped shapefile and extract it to your qgis_data directory in a subdirectory named ms:
https://github.com/GeospatialPython/Learn/raw/master/mississippi.zip
https://github.com/GeospatialPython/Learn/raw/master/Mississippi.zip
In addition to the shapefile, you will also need the MapComposer class. This class encapsulates the boilerplate composer code in a reusable way, to make adding other elements easier. You can download it from https://github.com/GeospatialPython/Learn/raw/master/MapComposer.py.
This file must...
