14. Visuals and Their Formatting
14.11 Pie, Donut and Treemap
Pie / Donut. Use for part-to-whole with 2–4 categories (Blinkit vs Amazon Now share of orders; Cash vs Digital). Avoid with many slices, similar values or trends. Field wells: Legend, Values, Details, Tooltips. Formatting: Slices colours, Detail labels (Category, Data value, Percent of total; position Outside/Inside), Rotation, Spacing (donut Inner radius), Legend.
Treemap. Nested rectangles for part-to-whole with many items or a hierarchy (श्रेणीरचना). Field wells: Category, Details, Values, Tooltips. Example: Category = Category, Details = Sub Category, Values = Total Sales. Avoid when exact comparison is needed. Formatting: Colors, Data labels, Category labels.
The bar chart test
If you cannot tell which of two slices is bigger without data labels, use a sorted bar chart instead.
Ravindra Bagale's Tip
Mitrano, khup students make pie charts with ten or more slices, which nobody can read. Keep pie and donut charts to two to five categories, or switch to a sorted bar chart. A treemap is fine for many categories when exact comparison isn't needed. Ghabru naka, don-teen vela kela ki savay hote.