// SLIDE 01 — HOOK

RADIAL COLUMN

The seasonal arc of temperature reads as a single shape — peak summer bars dominate the upper arc

Radial Column — Figure 60.1 — The seasonal arc of temperature reads as a single shape

NARRATION

The seasonal arc of temperature reads as a single shape , peak summer bars dominate the upper arc Figure 60.1 , The seasonal arc of temperature reads as a single shape

// SLIDE 02 — WHAT THIS CHART IS

WHAT THIS CHART IS.

A Radial Column Chart maps a standard bar chart onto a polar coordinate system. Each category is assigned an angular pos

What this chart is — The result is that all bars share a common centre rather than a common baseline. The overall silhouette of the chart — t

NARRATION

A Radial Column Chart maps a standard bar chart onto a polar coordinate system. Each category is assigned an angular position (a radial divider), and its bar extends outward from a central baseline along that angle. The value scale is encoded by concentric circles: the innermost circle represents the lowest scale value (often zero), and each successive circle outward represents a higher value. Bar length , measured radially from the baseline to the bar's outer edge , encodes the quantitative value.

// SLIDE 03 — WHY IT WAS CHOSEN HERE

WHY IT WAS CHOSEN HERE.

The data has 12 categories (months) with an inherent cyclical order — January follows December, the data wraps. The radi

Why it was chosen here — The seasonal pattern produces a recognisable shape — a broad arc of tall summer bars, a compressed arc of short winter b

NARRATION

The data has 12 categories (months) with an inherent cyclical order , January follows December, the data wraps. The radial column chart honours this cyclicality: the last bar and first bar are visually adjacent, so the viewer perceives the year as a continuous loop rather than a sequence with an arbitrary start and end.

// SLIDE 04 — THE PERCEPTUAL COST — AND WHEN

THE PERCEPTUAL COST — AND WHEN TO PAY IT

Radial columns suffer a well-documented perceptual distortion: bars further from the centre appear longer than equally-v

The perceptual cost — and when to pay it — This cost is worth paying only when two conditions hold: (1) the data is genuinely cyclical — it wraps, and the adjacenc

NARRATION

Radial columns suffer a well-documented perceptual distortion: bars further from the centre appear longer than equally-valued bars closer to it, because their outer arc is physically larger. This is the same distortion that makes pie slices and donut segments hard to compare precisely. The viewer's eye misjudges bar length when bars are at different angular positions, because length-along-a-radius is harder to compare than length-along-a-shared-baseline.

// SLIDE 05 — WHAT THE REJECTED ALTERNATIVE

WHAT THE REJECTED ALTERNATIVE BREAKS.

A standard Bar Chart — the direct equivalent — plots the same 12 months as horizontal or vertical bars on a linear axis.

What the rejected alternative breaks — A Radial Bar Chart (the close relative) uses concentric arcs rather than radial bars — each category is assigned a ring,

NARRATION

A standard Bar Chart , the direct equivalent , plots the same 12 months as horizontal or vertical bars on a linear axis. It is more precise for value retrieval and supports direct comparison between any two bars. What it loses is the cyclical wrap: December and January appear at opposite ends of the chart, breaking the visual continuity of the seasonal loop. For non-cyclical categorical data, the bar chart is always preferable. The radial form is justified only by the calendar's circularity.

// SLIDE 06 — PROMPT

PROMPT

radial-column.htmla full HTML page with inline CSS and inline D3 v7 (loaded from The chart should fill the viewport, be responsive on resi

radial-column/data.jsonthe data file the chart loads via d3.json("./radial-column/data.json"), with a fallback inline literal in the HTML if th

Average monthly temperatures (°F) for a fictional mid-latitude northern hemisphere city. 12 categories forming a completlow winter values, peak summer values — produces the characteristic radial column silhouette.

labelstring — category label displayed as the radial axis tick and tooltip header. For calendar data: month abbreviation. For

valuenumber — quantitative value encoded as bar length (radial distance from inner baseline to bar tip). Must be non-negative

NARRATION

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 radial column in D3 v7. Two files:

// SLIDE 07 — AI WAYBACK MACHINE

AI WAYBACK MACHINE.

Massimo Vignelli→Run this:→"Massimo Vignelli"→Now make the prompt better.

NARRATION

The ideas in this chapter didn't appear from nowhere. Massimo Vignelli designed the 1972 New York City subway map , a strict, geometric, topologically simplified diagram in the lineage of Harry Beck's London Underground map. His radial and grid-aware design philosophy shapes how circular and column-based charts are still composed. Massimo Vignelli, circa 1972. AI-generated portrait based on a public domain photograph (Wikimedia Commons).

// SLIDE 08 — THESIS

THE CORE CLAIM.

The ideas in this chapter didn't appear from nowhere. Massimo Vignelli designed the 1972 New York City subway map — a st

Massimo Vignelli, circa 1972. AI-generated portrait based on a public domain photograph (Wikimedia Commons).

NARRATION

// SLIDE 09 — CLOSE

ASK THE QUESTION. APPLY THE FRAMEWORK.

WHAT THIS CHART IS//WHY IT WAS CHOSEN HERE//THE PERCEPTUAL COST — AND

Brutalist D3 × Claude · Ch.60 · Radial Column

NARRATION

That is the framework. Brutalist D3 times Claude, chapter 60: Radial Column. The patterns are now in place. Apply them.