Healthcare commands 34 percent , crisis response receives the smallest share Figure 33.1 , Healthcare commands 34 percent , crisis response receives the smallest share

A Donut Chart is a Pie Chart with its center removed. The primary encoding is arc length , the angle each segment subtends , not area. This is a meaningful distinction: human perception ranks arc length as more accurate than area for quantitative comparison. The hollow center is not decorative; it creates a stable focal point for contextual annotation. Here it displays the portfolio total by default, and the hovered segment's value on interaction. That dual function would require a separate callout annotation in any other chart type.

The data tells a composition story : five mutually exclusive, exhaustive categories that together constitute total humanitarian AI investment. The categories sum to a meaningful whole , the $4.80B figure , which is the precondition for any part-to-whole chart. With five segments (the maximum recommended before an alternative becomes more readable), the donut renders without clutter. A horizontal bar chart would show values more precisely but would not communicate "these are parts of one thing" as immediately or as honestly.

A bar chart encodes values as position on a common scale , the most accurate perceptual channel. For comparison tasks it would be strictly superior. But the message here is composition , not comparison. A bar chart implies "rank these" rather than "these are pieces of something." Viewers looking at bars do not naturally compute the total or perceive the parts as a unified whole. The donut's circular closure is not decorative , it is the visual argument that the dataset is exhaustive .

The one decision worth knowing: segment order starts at 12 o'clock and runs clockwise by descending value. This is not default D3 behaviour , pie.sort(null) preserves data order, and the data is pre-sorted. Starting the largest segment at 12 o'clock anchors the viewer's reference point and makes the rank ordering immediately legible.

FT Visual Vocabulary + Abela FT Visual Vocabulary: Part-to-whole . Abela quadrant: Composition , showing how individual parts make up the whole at a point in time. Tufte: the donut's removed center reduces non-data ink versus a filled pie while opening space for genuine data display.

Paste this into Claude Code to generate a working version of this chart, plus its data file. The result will not be a perfect replica , the goal is that the reader can run the prompt, get a chart of this type, and read its source. Generate a complete, self-contained donut chart in D3 v7. Two files:

The ideas in this chapter didn't appear from nowhere. Mary Eleanor Spear developed practical chart-making standards through the 1950s , including the bar chart conventions and box-plot precursors that became US government statistical practice. Her 1952 textbook Charting Statistics was a standard reference for two generations. Mary Eleanor Spear, circa 1950. AI-generated portrait based on a public domain photograph (Wikimedia Commons).

The ideas in this chapter didn't appear from nowhere. Mary Eleanor Spear developed practical chart-making standards through the 1950s , including the bar chart conventions and box-plot precursors that became US government statistical practice. Her 1952 textbook Charting Statistics was a standard reference for two generations. Mary Eleanor Spear, circa 1950. AI-generated portrait based on a public domain photograph (Wikimedia Commons).