113 lines
3.7 KiB
Python
113 lines
3.7 KiB
Python
"""
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Build preference data for the reward model and DPO from real public datasets:
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- Anthropic/hh-rlhf (helpful/harmless human preferences)
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- HuggingFaceH4/ultrafeedback_binarized (LLM-judged preference pairs)
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Emits JSONL of ``{"prompt", "chosen", "rejected"}`` (train + held-out test). The held-out
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test split is what reward-model preference accuracy is measured on.
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Example:
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PYTHONPATH=. HF_HOME=/ephemeral/hf_cache python scripts/prepare_preference_data.py \
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--source both --max_per_source 40000 --out_dir /ephemeral/data
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"""
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from __future__ import annotations
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import argparse
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import json
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import os
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os.environ.setdefault("HF_HOME", "/ephemeral/hf_cache")
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_ASSISTANT_MARKER = "\n\nAssistant:"
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def _split_hh(text: str) -> tuple[str, str] | None:
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"""Split an HH-RLHF conversation string into (prompt_context, final_response)."""
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idx = text.rfind(_ASSISTANT_MARKER)
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if idx == -1:
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return None
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prompt = text[:idx].strip()
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response = text[idx + len(_ASSISTANT_MARKER):].strip()
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if not prompt or not response:
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return None
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return prompt, response
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def from_hh(max_n: int, split: str) -> list[dict]:
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from datasets import load_dataset
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ds = load_dataset("Anthropic/hh-rlhf", split=split)
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if max_n:
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ds = ds.select(range(min(max_n, len(ds))))
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out = []
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for ex in ds:
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c = _split_hh(ex["chosen"]); r = _split_hh(ex["rejected"])
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if not c or not r:
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continue
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prompt, chosen = c
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_, rejected = r
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if chosen == rejected:
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continue
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out.append({"prompt": prompt, "chosen": chosen, "rejected": rejected})
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return out
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def from_ultrafeedback(max_n: int, split: str) -> list[dict]:
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from datasets import load_dataset
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hf_split = "train_prefs" if split == "train" else "test_prefs"
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ds = load_dataset("HuggingFaceH4/ultrafeedback_binarized", split=hf_split)
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if max_n:
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ds = ds.select(range(min(max_n, len(ds))))
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out = []
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for ex in ds:
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prompt = ex["prompt"].strip()
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chosen = ex["chosen"][-1]["content"].strip()
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rejected = ex["rejected"][-1]["content"].strip()
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if not prompt or not chosen or not rejected or chosen == rejected:
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continue
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out.append({"prompt": prompt, "chosen": chosen, "rejected": rejected})
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return out
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def collect(source: str, max_n: int, split: str) -> list[dict]:
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rows: list[dict] = []
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if source in ("hh", "both"):
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print(f"Loading Anthropic/hh-rlhf [{split}] ...")
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rows += from_hh(max_n, split)
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if source in ("ultrafeedback", "both"):
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print(f"Loading ultrafeedback_binarized [{split}] ...")
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try:
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rows += from_ultrafeedback(max_n, split)
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except Exception as e: # noqa: BLE001
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print(f" (skipping ultrafeedback: {e})")
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return rows
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def write_jsonl(rows: list[dict], path: str) -> None:
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os.makedirs(os.path.dirname(path) or ".", exist_ok=True)
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with open(path, "w") as f:
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for r in rows:
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f.write(json.dumps(r) + "\n")
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print(f" wrote {len(rows)} pairs -> {path}")
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def main():
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p = argparse.ArgumentParser()
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p.add_argument("--source", choices=["hh", "ultrafeedback", "both"], default="both")
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p.add_argument("--max_per_source", type=int, default=40000)
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p.add_argument("--out_dir", default="/ephemeral/data")
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args = p.parse_args()
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train = collect(args.source, args.max_per_source, "train")
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test = collect(args.source, max(2000, args.max_per_source // 20), "test")
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import random
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random.Random(0).shuffle(train)
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write_jsonl(train, os.path.join(args.out_dir, "preferences.jsonl"))
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write_jsonl(test, os.path.join(args.out_dir, "preferences_test.jsonl"))
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if __name__ == "__main__":
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main()
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