vega

SKILL.md

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