Dorlings's Cartogram Algorithm

The applet on this page is a Java implementation of Dorling's cartogram algorithm. The size of the circles is proportional to the size of the selected variable (selected in the pop up menu).
Example
 
Buttons

• Popup-Menu (here: "Population"): choice of predefined variables
• Stop / Start: pausing and resuming of iterations
• Reset: circles go to their starting position
• My Data: paste your own data values into the appearing dialog
• Write: the calculated circles (size and position) are written to the Java log window
• -: scaling of the circles by the factor 0.9
• +: scaling by the factor 1.11111
• Names: without areal unit names the algorithm may be a little bit faster
• Change Colors: random color change

Hidden Features

You can pick a circle and observe the behaviour of the algorithm.

Parameters

The input to the applet consists of files describing the areal units (name, starting position, desired size with weighting variables in .dbf format) and their geometric relations (length and neighbours of boundary arcs). The geometry is derived from ArcInfo coverages.

Feedback, Availability

Feedback is welcome. Please contact me, if you have problems (operating system and browser version?) or new ideas, suggestions, comments, programming hints.

If you want to integrate Dorling into your web site send me a mail.

Thanks

Thanks to Mark Panning who's code is the base of this implementation. There are still some redrawing problems. The example shows the 171 communes of the Canton of Zurich, Switzerland.

Literature

Dorling, Daniel (1996): Area Cartograms: Their Use and Creation, Concepts and Techniques in Modern Geography (CATMOG), 59

Dykes, Jasond and David Unwin (1996): Maps of the Census: a Rough Guide

Version History
• 1.2 (30.1.00): entering of values via clipboard
• 1.1 (31.1.99)
• 1.00 (15.11.98): First version.