scripts/relabel_clean.py

"""Clean the dataset by training on MNIST (known-clean labels) + Paul Ricard
(visually verified, very clear digits), then using that model to filter/relabel
all racing data.

Strategy:
1. Train a strong CNN on MNIST + Paul Ricard (both have clean, unambiguous labels)
2. Run inference on ALL training data
3. Keep only samples where model agrees with label (or relabel if model is very confident)
4. Do the same for val
5. Rebuild parquet files and composites

Usage:
    uv run python scripts/relabel_clean.py
"""

import numpy as np
import pandas as pd
import io
import os

import torch
import torch.nn as nn
import torch.optim as optim
from torch.utils.data import DataLoader, TensorDataset
from PIL import Image
from datasets import Dataset, Image as HFImage

if __name__ != "__main__":
    import sys; sys.exit(0)

device = torch.device("cuda" if torch.cuda.is_available()
                       else "mps" if torch.backends.mps.is_available()
                       else "cpu")
print(f"Using device: {device}")


class CNN(nn.Module):
    def __init__(self):
        super().__init__()
        self.features = nn.Sequential(
            nn.Conv2d(1, 32, 3, padding=1), nn.BatchNorm2d(32), nn.ReLU(), nn.MaxPool2d(2),
            nn.Conv2d(32, 64, 3, padding=1), nn.BatchNorm2d(64), nn.ReLU(), nn.MaxPool2d(2),
            nn.Conv2d(64, 128, 3, padding=1), nn.BatchNorm2d(128), nn.ReLU(), nn.AdaptiveAvgPool2d(4))
        self.classifier = nn.Sequential(
            nn.Flatten(), nn.Linear(128 * 16, 256), nn.ReLU(), nn.Dropout(0.4), nn.Linear(256, 10))

    def forward(self, x):
        return self.classifier(self.features(x))


def load_images(df):
    imgs = []
    for _, row in df.iterrows():
        img = Image.open(io.BytesIO(row["image"]["bytes"])).convert("L")
        imgs.append(np.array(img, dtype=np.float32) / 255.0)
    return np.stack(imgs)[:, np.newaxis, :, :]


def train_model(X, y, epochs=40):
    model = CNN().to(device)
    opt = optim.Adam(model.parameters(), lr=1e-3, weight_decay=1e-4)
    scheduler = optim.lr_scheduler.CosineAnnealingLR(opt, epochs)
    crit = nn.CrossEntropyLoss()
    loader = DataLoader(
        TensorDataset(torch.tensor(X), torch.tensor(y, dtype=torch.long)),
        batch_size=64, shuffle=True)

    model.train()
    for epoch in range(epochs):
        total_loss = 0
        for xb, yb in loader:
            xb, yb = xb.to(device), yb.to(device)
            opt.zero_grad()
            loss = crit(model(xb), yb)
            loss.backward()
            opt.step()
            total_loss += loss.item()
        scheduler.step()
        if (epoch + 1) % 10 == 0:
            print(f"  epoch {epoch+1}/{epochs} loss={total_loss/len(loader):.4f}")

    return model


def predict(model, X):
    model.eval()
    with torch.no_grad():
        probs = torch.softmax(model(torch.tensor(X).to(device)), dim=1).cpu().numpy()
    return probs


# --- Step 1: Build clean seed dataset ---
print("\n=== Building clean seed dataset ===")
train_df = pd.read_parquet("data/train-00000-of-00001.parquet")
val_df = pd.read_parquet("data/validation-00000-of-00001.parquet")

# MNIST from train (known clean)
mnist = train_df[train_df["source"] == "mnist"]
print(f"MNIST: {len(mnist)} samples")

# Paul Ricard from train (visually verified, very clear white-on-black)
paul_ricard = train_df[train_df["source"] == "paul-ricard-alpine"]
print(f"Paul Ricard: {len(paul_ricard)} samples")

seed = pd.concat([mnist, paul_ricard], ignore_index=True)
X_seed = load_images(seed)
y_seed = seed["label"].values
print(f"Seed dataset: {len(seed)} samples")

# --- Step 2: Train ensemble on seed ---
print("\n=== Training 5-model ensemble on seed data ===")
models = []
for i in range(5):
    print(f"Model {i+1}/5:")
    # Bootstrap
    idx = np.random.choice(len(X_seed), len(X_seed), replace=True)
    model = train_model(X_seed[idx], y_seed[idx])
    models.append(model)

# --- Step 3: Predict on all data ---
print("\n=== Predicting on all data ===")

for split_name, df in [("train", train_df), ("validation", val_df)]:
    X = load_images(df)
    y = df["label"].values
    sources = df["source"].values

    # Ensemble predict
    probs = np.zeros((len(X), 10))
    for model in models:
        probs += predict(model, X)
    probs /= len(models)

    preds = probs.argmax(axis=1)
    conf = probs.max(axis=1)

    # For MNIST: keep as-is (they're the seed)
    # For racing: keep only where model agrees OR model is not confident
    keep = np.ones(len(df), dtype=bool)

    for i in range(len(df)):
        if sources[i] == "mnist":
            continue  # always keep
        if preds[i] != y[i] and conf[i] > 0.5:
            keep[i] = False

    dropped = (~keep).sum()
    print(f"\n{split_name}: {len(df)} -> {len(df) - dropped} (dropping {dropped})")

    # Per-label breakdown
    for label in range(10):
        mask = y == label
        drop_mask = mask & ~keep
        if drop_mask.sum() > 0:
            pred_dist = pd.Series(preds[drop_mask]).value_counts().to_dict()
            print(f"  label={label}: drop {drop_mask.sum()}/{mask.sum()} -> model says {pred_dist}")

    df_clean = df[keep].reset_index(drop=True)
    print(f"  Final distribution:")
    print(pd.crosstab(df_clean["label"], df_clean["source"]))

    ds = Dataset.from_pandas(df_clean)
    ds = ds.cast_column("image", HFImage())
    ds.to_parquet(f"data/{split_name}-00000-of-00001.parquet")

print("\nDone! Now run: uv run python scripts/make_composites.py")