You'll find an example of a set action in the Chapter 7 Complete.twbx workbook in the dashboard named Sales by Region and Category (set actions), which looks like this:
The dashboard consists of two views: a map and a bar chart. Selecting a Region on the map triggers a set action that updates the bar chart. A filter action would filter the bar chart, causing the length of each bar to only show the value for the selected region. Here, however, the set action is used to show the portion of the overall bar that belongs to that region while still retaining the full length of the bar for all regions.
To replicate this interactivity, ...