Tableau Desktop 9.2
When creating a dual axis map with one layer being a filled map, and the other being pie charts to identify specific locations; being able to filter only data from a specific axis as opposed to both.
Filled Map data = regions based on U.S. county lines (needs to stay intact regardless of filter application)
Pie Chart data = program locations broken down by individual characteristics (types of training offered at each location)
When filtering pie chart data, non-applicable counties/regions are filtered out leaving "holes" in the map.
Leaving the filled map (background) as a static image so to speak and having pie charts change as dictated by filters.
Full Map vs Partial Map (Filtered)