Editing Cartogram (section)

===Diagrammatic (Dorling) cartograms===
[[File:Wikipédia-Pays par liens.2011.07.svg|thumb|right|upright=1.35|Diagrammatic (Dorling) cartogram of the number of times each country is linked in the French-language Wikipedia.]]
In this approach, each district is replaced with a simple geometric shape of proportional size. Thus, the original shape is completely eliminated, and contiguity may be retained in a limited form or not at all. Although they are usually referred to as ''Dorling cartograms'' after Daniel Dorling's 1996 algorithm first facilitated their construction,<ref name="dorling1996">{{cite book |last1=Dorling |first1=Daniel |title=Area Cartograms: Their Use and Creation |date=1996 |volume=59|series=Concepts and Techniques in Modern Geography (CATMOG) |publisher=University of East Anglia}}</ref> these are actually the original form of cartogram, dating back to Levasseur (1876)<ref name="levasseur1876" /> and Raisz (1934).<ref name="raisz1934" /> Several options are available for the geometric shapes:
* '''Circles''' (Dorling), typically brought together to be touching and arranged to retain some semblance of the overall shape of the original space.<ref name="dorling1996"/> These often look like [[proportional symbol map]]s, and some consider them to be a hybrid between the two types of thematic map.
* '''Squares''' (Levasseur/Demers), treated in much the same way as the circles, although they do not generally fit together as simply.
* '''Rectangles''' (Raisz), in which the height and width of each rectangular district is adjusted to fit within an overall shape. The result looks much like a [[Treemapping|treemap diagram]], although the latter is generally sorted by size rather than geography. These are often contiguous, although the contiguity may be illusory because many of the districts that are adjacent in the map may not be the same as those that are adjacent in reality.

Because the districts are not at all recognizable, this approach is most useful and popular for situations in which the shapes would not be familiar to map readers anyway (e.g., [[United Kingdom Parliament constituencies|U.K. parliamentary constituencies]]) or where the districts are so familiar to map readers that their general distribution is sufficient information to recognize them (e.g., countries of the world). Typically, this method is used when it is more important for readers to ascertain the overall geographic pattern than to identify particular districts; if identification is needed, the individual geometric shapes are often labeled.