Skills vega

Create data-driven charts with Vega-Lite (declarative) and Vega (programmatic). Best for statistical visualization of numeric data — bar, line, scatter, heatmap, area, radar charts, and word clouds.

install

source · Clone the upstream repo

git clone https://github.com/markdown-viewer/skills

Claude Code · Install into ~/.claude/skills/

T=$(mktemp -d) && git clone --depth=1 https://github.com/markdown-viewer/skills "$T" && mkdir -p ~/.claude/skills && cp -r "$T/vega" ~/.claude/skills/markdown-viewer-skills-vega && rm -rf "$T"

manifest: vega/SKILL.md

source content

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

```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