14. Visuals and Their Formatting
14.11 Pie, Donut and Treemap
Start with a problem
Salman must show the category share for the review deck. His first draft is a pie chart with three slices; his second draft has 14 product slices.
Explain simply
Pie and donut charts show part-to-whole for a few items (up to about five). A treemap shows part-to-whole as nested rectangles and copes with more items or a hierarchy.
Show the data
| Category | Total Sales (₹) | Share |
|---|---|---|
| Dairy | 1,050 | 50.0% |
| Snacks | 650 | 31.0% |
| Fruits | 400 | 19.0% |
| Total | 2,100 | 100% |
About this data: This table uses columns: Category, Total Sales (₹), Share. This table uses columns: Wrong result, Reason, Correction. Values shown are the lesson examples already on this page (not a new dataset).
Fictional sample data. Practice file: visuals_orders_apr_may_2026.csv (source: src/practice/).
Demonstrate
- Insert Donut chart: Legend
Category, ValuesTotal Sales. - Format › Visual › Detail labels › Label contents Category, percent of total.
- Change to Treemap: Category
Category, ValuesTotal Sales. - Add
Storeto Details in the treemap to see nested rectangles.
Show the result
Your result should look like this (fictional sample):
| Category | Total Sales (₹) | Share |
|---|---|---|
| Dairy | 1,050 | 50.0% |
| Snacks | 650 | 31.0% |
| Fruits | 400 | 19.0% |
| Total | 2,100 | 100% |
Explain what happened
Each slice is the category's Total Sales divided by the total ₹2,100: Dairy 1,050 ÷ 2,100 = 50.0%. The treemap uses area instead of angle for the same proportions.
Explore further
- People compare lengths better than angles, so a sorted bar is often clearer.
- Use one strong colour for the slice you want to discuss.
Detailed reference for this lesson:
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. 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
Friends, many 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. Don't worry – after doing it two or three times, it becomes a habit.
Ravindra Bagale's Tip – मराठी
मित्रांनो, बरेच students दहा किंवा जास्त slices असलेले pie charts बनवतात, जे कोणालाच वाचता येत नाहीत. Pie आणि donut charts दोन ते पाच categories पर्यंतच ठेवा, किंवा sorted bar chart वापरा. अचूक तुलना लागत नसेल तर अनेक categories साठी treemap चालतो. घाबरू नका, दोन-तीन वेळा केलं की सवय होते.
Ravindra Bagale's Tip – हिंदी
दोस्तों, बहुत से students दस या ज़्यादा slices वाले pie charts बनाते हैं, जिन्हें कोई पढ़ नहीं पाता. Pie और donut charts को दो से पाँच categories तक ही रखो, या sorted bar chart पर जाओ. सटीक तुलना की ज़रूरत न हो तो कई categories के लिए treemap ठीक है. घबराओ मत, दो-तीन बार करने पर आदत हो जाती है.
Fix common mistakes
| Wrong result | Reason | Correction |
|---|---|---|
| 14 unreadable slices | Too many items | Use a bar chart or treemap; group small items |
| Percentages add up to 99% | Rounding | Show one decimal place or note rounding |
| Donut changes colour order across pages | Default palette | Fix colours per category in the theme |
Practise independently
Practice task
Make a donut by Platform. Give the two percentages.
Hints
- Blinkit 1,100, Amazon Now 1,000.
Solution
Blinkit 52.4% (1,100 ÷ 2,100), Amazon Now 47.6%.
Think like a professional
Many managers ask for pies. A professional delivers the pie when it is fine (few slices) and proposes a bar when it is not, with a reason the manager can accept.
Revision card