A self-contained HTML application for exploring all 256 elementary cellular automata rules.

Project is live at https://paraschopra.github.io/1d-ca/

1d-ca/
├── src/
│   └── index.html                     # Main app (single self-contained HTML/CSS/JS file)
├── tests/                             # Playwright headless browser tests
├── sprints/
│   ├── initial/                       # v1 sprint tracking
│   ├── v2/                            # v2 sprint tracking (prd.json, progress.txt)
│   └── v3/                            # v3 sprint tracking (tooltips, metric fixes, UI improvements)
└── README.md

• All 256 elementary CA rules displayed in responsive grid
• 128x128 grid per rule with wrap-around (periodic) boundaries
• Center cell or random initial configurations with density slider
• Sticky tab bar and controls bar for easy navigation while scrolling
• Click to expand: 512x512 high-res view with truth table, detailed metrics, and block entropy chart
• Modal density slider and randomize button for exploring different initial conditions per rule

• Entropy: Shannon entropy of cell states (0 = uniform, 1 = random)
• Density / Mean Field: Fraction of alive cells (global and time-averaged)
• Wolfram Class: 4-class behavioral classification (I–IV)
• Symmetry: Spatial mirror symmetry score
• Lyapunov Exponent: Perturbation sensitivity (positive = chaotic, negative = stable). Floors distance at 0.5 for absorbing rules
• Compressibility: RLE compression ratio (range [-1, 1]; negative for alternating patterns)
• Period: Temporal repetition detection
• Block Entropy H(L): Shannon entropy of length-L patterns (L=1–8), with entropy rate h and excess entropy E
• Hover tooltips on all metric labels across all UI surfaces

• Plots measured H(L) vs block length L with linear fit line (h·L + E)
• Legend distinguishing measured data from fit line
• Descriptive annotations for slope (h) and intercept (E) with qualitative labels

• 2D scatter plot of all 256 rules by selectable metrics
• Color-coded by Wolfram class
• Click any point to open rule detail modal

• Density sweep from 0% to 100% with multi-series line chart
• Critical density detection for phase transitions

• Side-by-side comparison of two rules
• Difference heatmap showing perturbation propagation speed

Playwright tests (headless browser):

npx playwright test

Project by @paraschopra