Australian Federal Budget 2014/15: Changes to Public Service Staffing Levels Visualized Using a D3.js Zoomable Treemap
A friend recently drew my attention to Ausviz, a site focussed on visualizations of Australian data, particularly data sets from data.gov.au. One of the first Ausviz visualizations I looked at uses a force-directed graph to visualize changes in public service staffing levels arising from the 2014/15 Federal Budget. The graph represents the hierarchy of ministries and departments, with the size and colour of leaf nodes encoding the change in departmental headcounts.
An alternative way of visualizing hierarchies is to use a treemap. The hierarchy is represented by a nested layout of rectangles. The size and colour of the rectangles is used to encode dimensions of the data.
So, taking inspiration from the Ausviz visualization I implemented a treemap to visualize the same data. The layout of rectangles represents the hierarchy of Federal Government ministries and departments. Rectangle sizes encode the numbers of staff in each department (2013/14 or 2014/15). Rectangle colours encode the changes in staffing levels (absolute or relative). The colour scale ranges from red (staff decrease) through white (no change) to green (staff increase).
You will need a "modern" browser to use the interactive version, which supports the following operations:
+ change the size encoding (2013/14 or 2014/15)
+ change the colour encoding (absolute or relative)
+ drill down into a ministry (click on a rectangle)
+ mouse over a rectangle to display a departmental tool-tip