feat: add run_pretrain.py; fix output-path naming and max_seq_len

- scripts/run_pretrain.py: single-command pre-training runner with
  timing estimate, loss-curve plot (matplotlib), and per-epoch report.
  Sets max_seq_len=256 (McGill sequences max out at 195 tokens, ~4x
  faster attention than the 512 default).
- src/train.py: normalise --output so pretrained.pt and pretrained both
  produce pretrained.pt + pretrained.log.csv (not pretrained.pt.log.csv).
  Serialize Path fields as strings in checkpoint to satisfy weights_only.
- requirements.txt: drop unused pandas/music21, add mido (pretty_midi dep).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
This commit is contained in:
2026-05-20 12:13:38 +03:00
parent 733e1fde1f
commit dd4f21f17f
3 changed files with 220 additions and 4 deletions
+1 -2
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@@ -4,11 +4,10 @@
# Core ML
torch==2.12.0
numpy==2.4.6
pandas==3.0.3
# Music processing
music21==10.1.0
pretty_midi==0.2.11
mido==1.3.3
# Visualization
matplotlib==3.10.9
+215
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@@ -0,0 +1,215 @@
"""Run full pre-training on the McGill corpus, then plot loss curves and
print a short diagnostic report.
Usage:
# Full run (training + plot + report)
python scripts/run_pretrain.py
# Skip training if a checkpoint already exists; only re-plot and report
python scripts/run_pretrain.py --skip-training
Outputs written:
checkpoints/pretrained.pt best checkpoint
checkpoints/pretrained.log.csv per-epoch metrics
checkpoints/pretrained_curves.png train/val loss plot
"""
from __future__ import annotations
import argparse
import csv
import logging
import math
import sys
from pathlib import Path
import matplotlib
matplotlib.use("Agg") # headless — no display required
import matplotlib.pyplot as plt
import torch
sys.path.insert(0, str(Path(__file__).resolve().parent.parent))
from src.model import ChordTransformer
from src.train import TrainConfig, train
from src.tokenizer import TOKEN_TO_ID
# ---------------------------------------------------------------------------
# Paths
# ---------------------------------------------------------------------------
DATA_DIR = Path("data/processed")
CHECKPOINT = Path("checkpoints/pretrained.pt")
LOG_CSV = Path("checkpoints/pretrained.log.csv")
CURVES_PNG = Path("checkpoints/pretrained_curves.png")
# ---------------------------------------------------------------------------
# Training config (mirrors the requested CLI invocation)
# ---------------------------------------------------------------------------
TRAIN_CFG = TrainConfig(
data_dir=DATA_DIR,
output=CHECKPOINT,
epochs=50,
batch_size=32,
lr=3e-4,
warmup_steps=200,
seed=42,
device="auto",
# Real McGill sequences are ≤ 195 tokens (p95 = 146, mean = 92).
# Using 256 instead of the 512 default cuts attention cost ~4x.
max_seq_len=256,
)
# ---------------------------------------------------------------------------
# Plotting
# ---------------------------------------------------------------------------
def plot_curves(log_csv: Path, out_png: Path) -> None:
epochs, train_losses, val_losses, val_ppls = [], [], [], []
with open(log_csv, newline="") as fh:
for row in csv.DictReader(fh):
epochs.append(int(row["epoch"]))
train_losses.append(float(row["train_loss"]))
val_losses.append(float(row["val_loss"]))
val_ppls.append(float(row["val_ppl"]))
fig, (ax1, ax2) = plt.subplots(1, 2, figsize=(11, 4))
ax1.plot(epochs, train_losses, label="train loss", linewidth=1.5)
ax1.plot(epochs, val_losses, label="val loss", linewidth=1.5)
best_epoch = epochs[val_losses.index(min(val_losses))]
ax1.axvline(best_epoch, color="grey", linestyle="--", linewidth=0.8,
label=f"best epoch {best_epoch}")
ax1.set_xlabel("epoch")
ax1.set_ylabel("cross-entropy loss")
ax1.set_title("Pre-training loss")
ax1.legend()
ax1.grid(True, alpha=0.3)
ax2.plot(epochs, val_ppls, color="tab:orange", linewidth=1.5)
ax2.axvline(best_epoch, color="grey", linestyle="--", linewidth=0.8)
ax2.set_xlabel("epoch")
ax2.set_ylabel("perplexity")
ax2.set_title("Val perplexity")
ax2.grid(True, alpha=0.3)
fig.tight_layout()
out_png.parent.mkdir(parents=True, exist_ok=True)
fig.savefig(out_png, dpi=150)
plt.close(fig)
print(f"[plot] saved → {out_png}")
# ---------------------------------------------------------------------------
# Report
# ---------------------------------------------------------------------------
def print_report(log_csv: Path, checkpoint: Path) -> None:
rows = []
with open(log_csv, newline="") as fh:
rows = list(csv.DictReader(fh))
if not rows:
print("[report] log CSV is empty — nothing to report")
return
val_losses = [float(r["val_loss"]) for r in rows]
best_idx = val_losses.index(min(val_losses))
best_row = rows[best_idx]
# Convergence heuristic: first epoch where val loss is within 1 % of best
best_loss = float(best_row["val_loss"])
conv_epoch = next(
(int(r["epoch"]) for r in rows if float(r["val_loss"]) <= best_loss * 1.01),
int(best_row["epoch"]),
)
# Parameter count from checkpoint
n_params = None
if checkpoint.exists():
ckpt = torch.load(checkpoint, weights_only=True)
mcfg = ckpt["model_config"]
model = ChordTransformer(**mcfg)
tied = model.token_emb.weight.numel()
n_params = sum(p.numel() for p in model.parameters()) - tied
print()
print("=" * 52)
print(" PRE-TRAINING REPORT")
print("=" * 52)
print(f" Total epochs run : {len(rows)}")
print(f" Best epoch (val loss) : {best_row['epoch']}")
print(f" Convergence epoch : {conv_epoch} (val ≤ best+1 %)")
print(f" Best val loss : {best_loss:.4f}")
print(f" Best val perplexity : {float(best_row['val_ppl']):.2f}")
print(f" Final train loss : {float(rows[-1]['train_loss']):.4f}")
if n_params is not None:
print(f" Unique parameters : {n_params:,}")
print(f" Checkpoint : {checkpoint}")
print(f" Log CSV : {log_csv}")
print("=" * 52)
print()
# Full epoch table for copy-paste into the report
print(f" {'epoch':>5} {'train':>8} {'val':>8} {'ppl':>7} {'lr':>10}")
print(f" {'-'*5} {'-'*8} {'-'*8} {'-'*7} {'-'*10}")
for r in rows:
marker = "" if int(r["epoch"]) == int(best_row["epoch"]) else ""
print(
f" {int(r['epoch']):>5} {float(r['train_loss']):>8.4f}"
f" {float(r['val_loss']):>8.4f} {float(r['val_ppl']):>7.2f}"
f" {float(r['lr']):>10.2e}{marker}"
)
print()
# ---------------------------------------------------------------------------
# Main
# ---------------------------------------------------------------------------
def main() -> None:
ap = argparse.ArgumentParser(description=__doc__,
formatter_class=argparse.RawDescriptionHelpFormatter)
ap.add_argument("--skip-training", action="store_true",
help="Skip training; re-plot and report from existing CSV.")
args = ap.parse_args()
logging.basicConfig(
level=logging.INFO,
format="%(asctime)s %(levelname)s %(message)s",
datefmt="%H:%M:%S",
)
if not args.skip_training:
if not DATA_DIR.exists():
print(f"ERROR: data directory not found: {DATA_DIR}", file=sys.stderr)
print("Run prepare_data.py first.", file=sys.stderr)
sys.exit(1)
import pathlib
n_train = len(list((DATA_DIR / "train").glob("*.pt")))
n_batches = (n_train + TRAIN_CFG.batch_size - 1) // TRAIN_CFG.batch_size
# Rough estimate: ~1.5 s/batch on CPU with seq_len≈196, faster on GPU.
est_epoch_s = n_batches * 1.5
device_label = "GPU" if __import__("torch").cuda.is_available() else "CPU"
print(
f"[run_pretrain] {n_train} train files, {n_batches} batches/epoch\n"
f"[run_pretrain] estimated time on {device_label}: "
f"~{est_epoch_s/60:.0f} min/epoch, "
f"~{TRAIN_CFG.epochs * est_epoch_s / 3600:.1f} h total\n"
f"[run_pretrain] (early stopping with patience={TRAIN_CFG.patience} may reduce this)\n"
)
train(TRAIN_CFG)
else:
if not LOG_CSV.exists():
print(f"ERROR: log CSV not found: {LOG_CSV}", file=sys.stderr)
sys.exit(1)
print(f"[skip-training] using existing log: {LOG_CSV}")
plot_curves(LOG_CSV, CURVES_PNG)
print_report(LOG_CSV, CHECKPOINT)
if __name__ == "__main__":
main()
+4 -2
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@@ -267,8 +267,10 @@ def train(cfg: TrainConfig) -> Path:
# ------------------------------------------------------------------
output_path = Path(cfg.output)
output_path.parent.mkdir(parents=True, exist_ok=True)
checkpoint_path = output_path.with_suffix(".pt")
log_csv_path = Path(str(output_path) + ".log.csv")
# Normalise: --output may be given with or without the .pt extension.
stem = output_path.with_suffix("") if output_path.suffix == ".pt" else output_path
checkpoint_path = stem.with_suffix(".pt")
log_csv_path = Path(str(stem) + ".log.csv")
with open(log_csv_path, "w", newline="") as fh:
writer = csv.writer(fh)