A cartogram is a map where some variable (e.g. population) is substituted for land area or distance. The geometry of the map is distorted to convey the information of this variable.
“Cartogram Creator” is a Python plugin for QGIS available through Carson Farmer’s repository.
To use this plugin, you need a polygon layer with the attribute you want to be represented in the cartogram. I’m using a small file of Austrian regions with population data:
The small island in the north-east is Vienna, the Austrian capital. With more than 1.5 million inhabitants, it is the region with highest population. This fact should be visible in the resulting cartogram.
I chose to run five iterations of the plugin algorithm. The plugin allows saving of each iteration’s result. This is how the shape of the region changes through the iterations:
We can see Vienna “growing”. The final result looks like this:
The cartogram shows pretty clearly that the Vienna region is home to a considerable population.