@walterra/pi-charts

Vega-Lite chart extension for pi coding agent - render data visualizations as inline terminal images.

Installation

pi install npm:@walterra/pi-charts

This installs the package globally and adds it to your pi settings.

Compatibility

• Tested with pi 0.62.0

Features

• Declarative Visualizations: Use Vega-Lite JSON specs to describe charts
• Auto Dependencies: Python, altair, pandas, vl-convert auto-installed via uv
• Inline Display: Charts render directly in terminals supporting inline images (Ghostty, Kitty, iTerm2, WezTerm)
• Save to File: Optionally save charts to PNG files

Tool: vega_chart

Renders a Vega-Lite specification as a PNG image.

Parameters

Parameter	Type	Required	Description
spec	string	✅	Vega-Lite JSON specification
tsv_data	string		Optional TSV data to replace spec.data.values
width	number		Chart width in pixels (default: 600)
height	number		Chart height in pixels (default: 400)
save_path	string		Optional file path to save the PNG

Example

{
  "$schema": "https://vega.github.io/schema/vega-lite/v5.json",
  "data": {
    "values": [
      { "category": "A", "value": 28 },
      { "category": "B", "value": 55 },
      { "category": "C", "value": 43 }
    ]
  },
  "mark": "bar",
  "encoding": {
    "x": { "field": "category", "type": "nominal" },
    "y": { "field": "value", "type": "quantitative" }
  }
}

Reference Documentation

See vega-lite-reference.md for documentation on:

• Data types and encoding channels
• All mark types and properties
• Common pitfalls to avoid
• Professional chart patterns
• Theming and best practices

License

MIT