For the first assignment of the Couse Data Visualisation I opted to use a dataset provided by CBS (Centraal Bureau voor de Statistiek), a Dutch Goverment body that publishes statistical information about The Netherlands.
I chose to use “wijk- en buurtkaart 2009“, a dataset that holds information about geographic regions in the Netherlands as I am interrested in learing about geo spatial information visualisation.
The dataset describes the information on three levels namely: province, municipality and neighborhood. After my initial prototype I opted for the municipalities as my level of granularity.
My first order of business was to find ways to extract data from the ESRI shapefile in such a way that I could keep a usefull identifier per shape that I extracted.
After some googling I found a Perl script (shptosvg) to convert shapefiles into SVG. This worked fine for the part that it did extract the shapes and wrote out a nice SVG. It did not work so well for my proposes in that it did not write out a suitable identifier to associate each shape with the corresponding data. After some reading up on perl I make it write out the the municipality code as an id tag with each polygon.
When trying to load the SVG in Inkscape I found out that my modification had an error. The is needs to be unique but my data had cases where multiple polygons belonged to one municipality. I solved this by adding some junk as padding to the identifier and then during the SVG stage stripping the junk off.
Not that I had a nice map displaying I needed to be able to access my dataset in order to do somethign with the data and the map. For this I went back to the shptosvg Perl script and mangled that into spitting out all data fields for each shape into something that is so close to json that adding a head and tail made it into valid JSON.