热力图把值编码为行列网格中单元格的色值。卢阿 1873 年犯罪表；后来是贝尔坦与 1990 年代基因芯片。
工作报告、广告与作业中适合同时看两个分类轴上的模式。若精确读数，或不对色盲友好的彩虹，换一种形式。
Rules
- 规则 1 — Use 行列网格中单元格的色值 as one channel, not two.
- 规则 2 — Direct labels beat a distant legend.
- 规则 3 — Do not hide zero. If you break the axis, say so.
- 规则 4 — Colour encodes category or magnitude, not both.
- 规则 5 — Put the claim in the title, not just “热力图”.
- 规则 6 — Source and period, even in small type.
Palette
- 色板 1 — Categories: distinct hues. Sequences: one hue, changing value.
- 色板 2 — Diverging: a neutral centre, emphasis at both ends.
- 色板 3 — One brand colour plus greys beats a rainbow.
- 色板 4 — Check contrast on a projector and in greyscale print.
Type
- 文字 1 — Tabular figures for numbers. Do not pour body copy into the chart.
- 文字 2 — Titles as sentences; axes as short nouns.
- 文字 3 — For CJK, drop weight one step and leave tracking.
热力图: honour 行列网格中单元格的色值, and switch when 精确读数，或不对色盲友好的彩虹.