Archive for the ‘Treemap’ Category

A treemap representing the amount spent on Housing benefit

November 14, 2010

A colleague and I recently requested “Housing benefit cost data for every local authority within the UK (England, Scotland, Wales and NI), including the amount per local authority broken down into local authority and private properties per local authority. Specifically the maximum, minimum, mean, median, quartile 1, quartile 3, 10th percentile and 90th percentile for each local authority and private properties within each local authority.” via a Freedom of Information request of the Department for Work and Pensions.

Of course, now housing benefit, well all benefits, are in the news so this is almost timely (maybe a few weeks out, but I have been really busy with my day job!)

The response to our request was “As you have specifically requested cost information by the mean, median, quartile 1, quartile 3, 10th percentile and 90th percentile we have interrogated our databases and produced the attached analysis which is based on weekly award of Housing Benefit at March 2010. Further information on Housing Benefit is available on the DWP website at: . In addition, Housing Benefit expenditure by local authority is available at:

The information you requested for maximum and minimum is being withheld as it falls under the exemption in section 40 of the Freedom of Information Act. This exemption covers personal information about a third party and if provided could lead to a reasonable chance of individual claimants and their families being identified. This would breach the families’ right to privacy contrary to the Data Protection Act. ”

We thought it might be interesting to view this data as a treemap, it gives a good overview of the data allowing you to explore different areas and see which have the highest and lowest claims at each level. Each box represents the average weekly amount of housing benefit for the specified area, in sterling.

As before, I have produced the visualisation in Processing utilising the functionality I learnt about in Ben Fry’s book Visualising data. You can see my other example of a treemap here.

A Treemap to find a rental bike in London using Processing

August 30, 2010

I was recently searching the web for news stories about the new rental bikes in London. In the process I stumbled across an API, produced by Adrian Short.

Upon seeing this data I had an epiphany!!! I have come across numerous APIs in my travels of the web, but I realised I could do something with this data!

Boris Bikes

One of the comments journalists have made, along with a few friends, is that either trying to locate a bay of bikes, knowing if there are any bikes available, or if there is room to park your bike when you get there. Here the treemap comes into its own.

Some background on treemaps (for those who don’t know): “Ben Schneiderman, of the Human-Computer Interaction Laboratory (HCIL) at the University of Maryland, worked out a set of algorithms to subdivide 2D space to show the relative size of files and directories (see He call the representation a treemap, referencing the two-dimensional mapping of tree structures.” [quote taken from Ben’s book]

I had the idea from Ben Fry’s book Visualising Data in which he uses Ben Shneiderman’s Treemap software (which I have also utilised)

Before visualising this data as is, I decided I wanted to create a top layer, that is the location (i.e. North, East, South, West) of London you want to investigate, and when you drill in you can then view all of the regions in that location, and then you can drill in further to see the specifics. For each level I decided to have a info box follow the mouse point to give the full details of what you were looking at. Remember the size of the rectangle represent how full the dock is, if it is full of bike the rectangle is large, if it empty of bike the rectangle is small.

To drill into the data Left Mouse on the Party which will take you in a level. To return a level, or more, Right Mouse Click.

I can’t thank Adrian Short enough for this, Boris Bikes for hosting the link to the API, and the Processing project.

I really like how it looks (no surprise there!)?

As ever this is a working prototype and I would interested to hear any feedback? Of course, because this is a Processing Application it is a Java Applet and because the applet is accessing the API it needs to be signed. You will have to allow access for the applet to work. Have a play (