100 People , Who Has Access to Clean Energy? Figure 35.1 , 100 People , Who Has Access to Clean Energy?

A dot matrix chart represents a population as a uniform grid of discrete marks, each dot encoding exactly one unit , here, one percent. Categories are distinguished by color, with the grid filled sequentially. The perceptual mechanism is two-fold: counting (the viewer tallies dots in a category by scanning clusters) and area estimation (larger clusters read as larger proportions without requiring arithmetic). Because the total is always fixed , 100 dots , the viewer can compare proportions across all categories against a known denominator.

The dataset is a population divided into five discrete, mutually exclusive categories that sum to 100 percent. The message is about proportional distribution , not trend, not correlation, not ranking. A pie chart serves the same purpose but activates angle estimation, the least accurate quantitative perceptual channel. A stacked bar works for single-series but becomes unwieldy for comparison. The dot matrix exploits position and grouping simultaneously: the visual system pre-attentively detects clusters of same-colored dots, making the largest categories visible before any label is read.

A standard pie chart fails in two ways. It encodes magnitude as arc angle , a channel where human perception is consistently less accurate than position judgments. And distinguishing five similarly-sized slices requires comparing non-adjacent arc lengths, introducing error. The dot matrix keeps all categories on the same spatial field. A treemap is the strongest alternative when the part-to-whole structure is hierarchical; for flat single-level proportions with a countable denominator the dot matrix is preferable because each unit is individually traceable , something treemaps sacrifice for space-efficiency.

FRAMEWORK FT Visual Vocabulary category: Part-to-whole , "Show how a single entity is divided into its component parts." Abela quadrant: Composition (how individual parts make up the whole, static). Tufte principle: every dot is data , the grid is the axis, no ink is decorative.

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 dot matrix in D3 v7. Two files:

The ideas in this chapter didn't appear from nowhere. John Horton Conway invented the Game of Life in 1970 , a dot-matrix cellular automaton where each cell lives or dies by a few simple rules. The grid is the simplest possible dot matrix; the patterns that emerge are still studied as a model of complex systems. John Horton Conway, circa 1990. AI-generated portrait based on a public domain photograph (Wikimedia Commons).

The ideas in this chapter didn't appear from nowhere. John Horton Conway invented the Game of Life in 1970 , a dot-matrix cellular automaton where each cell lives or dies by a few simple rules. The grid is the simplest possible dot matrix; the patterns that emerge are still studied as a model of complex systems. John Horton Conway, circa 1990. AI-generated portrait based on a public domain photograph (Wikimedia Commons).