Processing, week 4: Case-Shiller Home Price Indices

Originally published April 06, 2009.
Information provided in this post may be out of date.

See my post of May 26, 2009 for a more up-to-date Case-Shiller Home Price Index</a> graph.

screenshot-sketch_apr04aI must admit, I’ve been extremely lazy about reading Visualizing Data or even updating this blog… but, this post should make up for it.

Earlier this week I skimmed a WSJ blog and article on the Case-Shiller Home Price Index and thought to myself “time for a graph!”

For the uninitiated, Case-Shiller tracks home prices in 20 metro areas. As WSJ states, “[the index has] a base value of 100 in January 2000. So a current index value of 150 translates to a 50% appreciation rate since January 2000 for a typical home located within the metro market.”

This program graphs the history of each city’s home price index. Not satisfied with just a plain-old graph, I added some aesthetic and functional features. The 20-city composite is shown for reference. Moving the mouse over the graph will highlight and display the index for a given point in time. Clicking the mouse will advance to another city.

Oops, your browser does not have a Java Plug-in. Get the latest Java Plug-in here. Or, if you have Java but can't use the Plug-in, feel free to download the program as an executable jar. Here's a screen shot of what you're missing. screenshot-sketch_apr04a

The graph’s data comes from a static CSV which I slightly hand-modified from the original XLS spreadsheet.

It’s interesting the number of little things I find missing or bothersome. For example, I’d like to use curveVertex() instead of vertex() for a smoother line curve, but by nature it doesn’t display the first and last data points. Fortunately there are enough data points and few large jumps/drops so the graph does not appear jagged. I could go on…

Taking a break from the book and making something useful has been fun.