Continuously Variable Proportional Circle Map

http://geographyfieldwork.com/DataPresentationMappingTechniques.htm

This map is an example of a continuously variable proportional circle map. Unlike a regular proportional circle map, here, we have another variable in place. The circles do still change with frequency like with a proportional circle map, but they also look at other things. Obviously this map is in another language, so naming those variables is hard, but we can also see that the circles change with the frequency and within these frequencies, we can see further variables being analyzed.