Visualizing complex multidimensional data using heat maps

The heat map visualization is actually two visualizations in one. At a basic level, it is a simple heat map, which we will get to shortly; at a more advanced level, it is also a dendrogram, or tree-structured graph.

Heat maps

A heat map is very similar in concept to a cross table, or even just a spreadsheet, except instead of numbers, each cell is configured to display a color that reflects an underlying number. It provides a very intuitive representation of the relative values of complex multidimensional data. Compare the following visualizations (a cross table and a heat map) of monthly temperatures for a selection of American states. They are equivalent, except that...