NowChessSystems/modules/official-bots/python

NNUE Python Pipeline

Central CLI for training and exporting chess evaluation neural networks (NNUE).

Directory Structure

python/
├── nnue.py              # Main CLI entry point
├── src/                 # Python modules
│   ├── generate.py      # Generate random chess positions
│   ├── label.py         # Label positions with Stockfish
│   ├── train.py         # Train NNUE model
│   └── export.py        # Export weights to Scala
├── data/                # Training data (gitignored)
│   ├── positions.txt
│   └── training_data.jsonl
└── weights/             # Model weights (gitignored)
    ├── nnue_weights_v1.pt
    ├── nnue_weights_v1_metadata.json
    └── ...

Quick Start

# Train a new model (500k positions, auto-detect checkpoint)
python nnue.py train

# Train from specific checkpoint
python nnue.py train --from-checkpoint 2

# Train with custom games count
python nnue.py train --games 200000

# Train with custom positions file
python nnue.py train --positions-file my_positions.txt

# Export specific version to Scala
python nnue.py export 2

# List all checkpoints
python nnue.py list

CLI Commands

train - Train NNUE model

python nnue.py train [OPTIONS]

Options:

• --from-checkpoint N - Resume from checkpoint version N (default: uses latest)
• --games N - Number of games to generate (default: 500000)
• --positions-file FILE - Use existing positions file instead of generating
• --stockfish PATH - Path to Stockfish binary (default: $STOCKFISH_PATH or /usr/games/stockfish)

Examples:

# Train with latest checkpoint
python nnue.py train

# Train from v2 with 100k games
python nnue.py train --from-checkpoint 2 --games 100000

# Train with custom positions
python nnue.py train --positions-file my_games.txt --stockfish /opt/stockfish/sf15

export - Export weights to Scala

python nnue.py export WEIGHTS [output_path]

Arguments:

• WEIGHTS - Version number (e.g., 2) or full filename (e.g., nnue_weights_v2.pt)

Examples:

# Export version 2
python nnue.py export 2

# Export with full filename
python nnue.py export nnue_weights_v3.pt

Output goes to ../src/main/scala/de/nowchess/bot/bots/nnue/NNUEWeights_vN.scala

list - List available checkpoints

python nnue.py list

Shows all available model versions with file sizes.

Data Flow

1. Generate → data/positions.txt

   • Random chess positions from 8-20 move openings
   • Filters out checks, game-over states, and captures

2. Label → data/training_data.jsonl

   • Evaluates each position with Stockfish at depth 12
   • Stores FEN + evaluation in JSONL format

3. Train → weights/nnue_weights_vN.pt

   • Trains neural network on labeled positions
   • Auto-versioning (v1, v2, v3, etc.)
   • Saves metadata alongside weights

4. Export → NNUEWeights_vN.scala

   • Converts weights to Scala object
   • Ready for integration into bot

Versioning

• Models are automatically versioned (v1, v2, v3, etc.)
• Each version gets a _metadata.json file with training info
• Training from checkpoint uses latest version unless specified with --from-checkpoint

Files

• data/ and weights/ are gitignored (local artifacts)
• Documentation in docs/ explains training, debugging, and incremental improvements
• Source modules in src/ are independent and can be imported for custom workflows