---
dataset_info:
  features:
  - name: fen
    dtype: string
  - name: n_moves
    sequence: int64
  - name: term_n_moves
    sequence: int64
  - name: term_reason
    sequence: int64
  - name: term_white_wins
    sequence: bool
  splits:
  - name: train
    num_bytes: 9224260318
    num_examples: 100000054
  download_size: 4539320801
  dataset_size: 9224260318
configs:
- config_name: default
  data_files:
  - split: train
    path: data/train-*
---

# 100M Random Chess Boards

This dataset contains 100 million randomly sampled chess board positions. The process to generate each board state is as follows:

1. **Game Simulation**
- 100 million games were played, with each move being randomly determined until the game ended (i.e., until checkmate, stalemate, or draw).
2. **Board Sampling**
- From each game, a single random board state was selected at some point in the game.

Columns other than **fen** represent statistics for the sample. Most boards are sampled only once, however for example, the most common board, the initial board, is sampled 378,310 times. This comprises a single row with each column other than **fen** being 378,310 long.

# Columns

- **fen**: The FEN (Forsyth-Edwards Notation) representing the randomly sampled board position.
- **n_moves**: The number of moves made from the start of the game to reach the sampled FEN position.
- **term_n_moves**: The total number of moves in the random game before it terminated.
- **term_reason**: The reason the game ended. ([Codes](https://python-chess.readthedocs.io/en/latest/core.html#chess.Termination))
- **term_white_wins**: Indicates whether white won the game (true/false). null indicates a tie. Note that all games are complete, but the sampled board position is from an intermediate point.

# Code

```python3
from tqdm import tqdm
import collections
import chess
import random
from datasets import Dataset

import os
from multiprocessing import Process, Queue


def random_fen():
    """
    Play random game to completion
    backtrack random uniform number of moves
    """
    board = chess.Board()
    num_moves = 0
    while True:
        board.push(random.choice(list(board.legal_moves)))
        num_moves += 1
        if board.is_game_over():
            outcome = board.outcome()
            revert_moves = random.randint(0, num_moves)
            for _ in range(revert_moves):
                board.pop()
            fen_num_moves = num_moves - revert_moves
            termination_reason = outcome.termination.value
            white_is_winner = outcome.winner
            return board.fen(), fen_num_moves, num_moves, termination_reason, white_is_winner


def batched_random_fen(queue, batch_size=100):
    while True:
        fens = []
        while len(fens) < batch_size:
            fens.append(random_fen())
        queue.put(fens)


def generate_fens_parallel(N):
    all_fens = collections.defaultdict(
        lambda: {"n_moves": [], "term_n_moves": [], "term_reason": [], "term_white_wins": []}
    )
    queue = Queue()
    num_workers = os.cpu_count() // 2

    # Start worker processes in advance
    workers = []
    for _ in range(num_workers):
        worker = Process(target=batched_random_fen, args=(queue,))
        worker.daemon = True  # Ensures the process terminates with the main process
        workers.append(worker)
        worker.start()

    with tqdm(total=N, desc="FENs Captured") as pbar:
        for i in range(1_000_000_000_000):
            for fen, board_num_moves, final_state_num_moves, final_result, final_is_white_winner in queue.get():
                all_fens[fen]["n_moves"].append(board_num_moves)
                all_fens[fen]["term_n_moves"].append(final_state_num_moves)
                all_fens[fen]["term_reason"].append(final_result)
                all_fens[fen]["term_white_wins"].append(final_is_white_winner)

            if i % 100 == 0:
                pbar.n = len(all_fens)
                pbar.last_print_n = len(all_fens)
                pbar.refresh()

            if len(all_fens) >= N:
                break

    # Terminate workers
    for worker in workers:
        worker.terminate()

    # flatten
    return [{"fen": k, **v} for k, v in all_fens.items()]


if __name__ == "__main__":
    board_dicts = list(generate_fens_parallel(100_000_000))
    ds = Dataset.from_dict({key: [dic[key] for dic in board_dicts] for key in board_dicts[0]})
    ds.save_to_disk("random_uniform_chess_boards.hf")
    # ds = datasets.load_from_disk("random_uniform_chess_boards.hf")
    # ds.push_to_hub(...)
```