Nested rectangles sized by a number
A treemap draws nested rectangles. Area stands for a number such as revenue, file size, or a portfolio weight. Parents contain children, so structure and magnitude show up together.
A pie chart is the neighbor for a single whole split into slices, with no nesting. Use a pie when there is only one level. Stay here when groups contain groups.
Treemap or pie
Choose a treemap for a hierarchy with sizes, such as region, then product. Choose a pie chart for one level of shares. Choose an XY chart when the comparison is along axes rather than area inside a parent.
Give every leaf a size
1. Provide a number for each leaf
A rectangle without a value cannot be sized. Add the figure in the prompt and check the draft.
2. Keep the nesting shallow
Two levels are usually enough. A third level is fine for a few parents. Deeper trees turn into slivers.
3. Flatten what is really a pie
If there is no parent, switch to a pie chart. A treemap of one level hides the hierarchy you did not have.
How to phrase the prompt
State the unit, such as revenue in dollars or size in megabytes. Then list parents and their children with values. Keep names short. Do not include dates. A trend belongs on an XY chart.
Treemap questions
- Why are some rectangles tiny?
- The values really are small, or too many leaves share one parent. Group the tail into a single child named other.
- Can I compare two years?
- Use two treemaps, or switch to an XY chart if the year is an axis. One treemap shows one set of weights.
- What do I fix first on the draft?
- Parent membership and the unit. A product under the wrong region, or a mix of percent and money, will mislead before the colors do.