py2vega-ts 🐍 -> 📊

A TypeScript library that converts Python code to Typescript's Vega expressions with the help of py-ast

Installation

npm install py2vega-ts

Development

Setup

# Install dependencies
  npm install

# Build
  npm run build

Testing

# Run tests
  npm run test

Linting

# install pre-commit hooks
  pre-commit install

# fix linting issues
  pre-commit run --all-files

Quick Start

import { py2vega } from 'py2vega-ts';

// Simple comparison
const vega = py2vega('datum.value > 100');
console.log(vega);
// Output: datum.value > 100
// Ternary operator
const colored = py2vega("'red' if datum.status == 'alert' else 'green'");
console.log(colored);
// Output: ((datum.status == 'alert') ? 'red' : 'green')

// Complex expression
const complex = py2vega('abs(datum.value) * 2 if datum.active else 0');
console.log(complex);
// Output: (datum.active ? (abs(datum.value) * 2) : 0)

📖 Supported Python Syntax

Data Access

datum.field_name
datum.magnitude
datum.coordinates.x

Comparisons

datum.value > 100
datum.value < 50
datum.value == 5
datum.value != 10
datum.value >= 100
datum.value <= 50
datum.a < datum.b

Arithmetic Operations

datum.a + datum.b
datum.a - datum.b
datum.a * datum.b
datum.a / datum.b
datum.a % datum.b
-datum.value

Logical Operations

datum.a > 5 and datum.b < 10
# datum.a > 5 && datum.b < 10

datum.status == "A" or datum.status == "B"
# datum.status == "A" || datum.status == "B"

not (datum.value > 100)
# !(datum.value > 100)

Ternary Operator (If-Else)

42 if datum.value > 100 else 10
# datum.value > 100 ? 42 : 10

# Nested ternaries
'red' if datum.severity > 8 else 'yellow' if datum.severity > 5 else 'green'
# datum.severity > 8 ? 'red' : datum.severity > 5 ? 'yellow' : 'green'

Related Projects

• vega2ol - Convert Vega expressions to OpenLayers
• py2vega - Python package for this functionality
• JupyterGIS - Web-based GIS in Jupyter

Made with ❤️ for Jupyter lovers and geospatial enthusiasts.