vega

Design

Create data-driven charts with Vega-Lite (simple) and Vega (advanced). Best for bar, line, scatter, heatmap, area charts, and multi-series analytics. Use when you have numeric data arrays needing statistical visualization. Vega for radar charts and word clouds. NOT for process diagrams (use mermaid) or quick KPI cards (use infographic).

QUICK START

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Source SKILL.md: https://github.com/majiayu000/claude-skill-registry/blob/HEAD/skills/data/vega/SKILL.md

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Vega / Vega-Lite Visualizer

Quick Start: Structure data as array of objects → Choose mark type (bar/line/point/area/arc/rect) → Map encodings (x, y, color, size) to fields → Set data types (quantitative/nominal/ordinal/temporal) → Wrap in ```vega-lite or ```vega fence. Always include $schema, use valid JSON with double quotes, field names are case-sensitive. Use Vega-Lite for 90% of charts; Vega only for radar, word cloud, force-directed.

Critical Syntax Rules

Rule 1: Always Include Schema

"$schema": "https://vega.github.io/schema/vega-lite/v5.json"

Rule 2: Valid JSON Only

❌ {field: "x",}     → Trailing comma, unquoted key
✅ {"field": "x"}    → Proper JSON

Rule 3: Field Names Must Match Data

❌ "field": "Category"  when data has "category"
✅ "field": "category"  → Case-sensitive match

Rule 4: Type Must Be Valid

✅ quantitative | nominal | ordinal | temporal
❌ numeric | string | date

Common Pitfalls

Issue	Solution
Chart not rendering	Check JSON validity, verify `$schema`
Data not showing	Field names must match exactly
Wrong chart type	Match mark to data structure
Colors not visible	Check color scale contrast
Dual-axis issues	Add `resolve: {scale: {y: "independent"}}`

Output Format

```vega-lite
{...}
```

Or for full Vega:

```vega
{...}
```

Related Files

For advanced chart patterns and complex visualizations, refer to references below:

examples.md — Stacked bar, grouped bar, multi-series line, area, heatmap, radar (Vega), word cloud (Vega), and interactive chart examples