The tree map, also known as a heat map, visualizes values by dividing an area into a set of rectangles. The following screenshot shows an example of a tree map:
As you can see, two variables are used in this chart: one variable expressed by the relative size of each rectangle and another one illustrated by the color intensity. Instead of using the tree map, you can also choose the scatter plot chart to display two variables in one chart.
For this recipe, we can reuse the file we created in the Using a scatter plot chart recipe.
The tree map arranges the rectangles from big to small. The Cat 5 data (most expensive houses) is presented on the far left-hand side, while Cat 1 (cheapest houses) is illustrated by the block on the lower right-hand side. This rectangle also has the lightest color, indicating the lowest Weeks until sale value. In the recipe, we changed the colors to a more extreme range so that the differences between the rectangles are clearer.