475 lines
16 KiB
Python
475 lines
16 KiB
Python
"""IFD (Instruction Following Difficulty) data quality scoring.
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IFD = conditional_NLL / unconditional_NLL
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- Messages format: plain text concatenation (no chat template)
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- Plain format: raw instr_key + resp_key fields
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v2 changelog:
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- Same token set: unconditional pass prefixes resp with a plain-text sentinel
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(default ``\\n``; use ``--sentinel_text ""`` for bos/pad fallback).
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Both branches predict the identical N resp tokens.
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Single-token answers (rl=1) are now supported.
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- ctx_len tracked in output
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- skip_reason for None samples (no more silent None)
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- --per_token for per-token IFD breakdown
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"""
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import argparse
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import json
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import statistics
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import torch
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import torch.nn.functional as F
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import tqdm
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from astrai.model import AutoModel
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from astrai.tokenize import AutoTokenizer
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def _pack_bins(pairs, max_len):
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"""BFD bin packing: pack (c+r) into bins of max total length."""
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indexed = sorted(enumerate(pairs), key=lambda x: -(len(x[1][0]) + len(x[1][1])))
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bins = []
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lengths = []
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for orig_idx, (c, r) in indexed:
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size = len(c) + len(r)
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best_bin = -1
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for bi, rem in enumerate(lengths):
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if rem >= size:
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if best_bin < 0 or rem < lengths[best_bin]:
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best_bin = bi
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if best_bin >= 0:
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bins[best_bin].append((orig_idx, c, r))
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lengths[best_bin] -= size
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else:
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bins.append([(orig_idx, c, r)])
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lengths.append(max_len - size)
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return bins
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def _resolve_sentinel_ids(tokenizer, sentinel_text):
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"""Tokenize the sentinel text for the unconditional pass prefix.
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Falls back to bos/pad_token_id when sentinel_text is empty or
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cannot be encoded.
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"""
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if sentinel_text:
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ids = tokenizer.encode(sentinel_text, add_special_tokens=False)
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if ids:
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return ids
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for attr in ("bos_token_id", "pad_token_id", "eos_token_id"):
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tid = getattr(tokenizer, attr, None)
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if tid is not None:
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return [tid]
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return [0]
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@torch.inference_mode()
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def _score_batch(
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pairs, model, device, max_len=2048, sentinel_ids=None, per_token=False
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):
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"""BFD-packed IFD with text-sentinel-anchored unconditional pass.
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Conditional: (ctx + resp[0..i-1]) → resp[i], i = 0..N-1
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Unconditional: (<sentinel> + resp[0..i-1]) → resp[i], i = 0..N-1
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Both branches predict the identical N response tokens. A short
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plain-text sentinel gives the unconditional pass a prefix so that
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every response token can be predicted. Single-token answers (rl=1)
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are supported.
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"""
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if not pairs:
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return []
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if sentinel_ids is None:
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sentinel_ids = [0]
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bins = _pack_bins(pairs, max_len)
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result = [None] * len(pairs)
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# ---- conditional pass (packed, per-document position IDs) ----
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for bin_items in bins:
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seq_ids = []
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global_pos = []
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doc_ids = []
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doc_offsets = []
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for di, (orig_idx, c, r) in enumerate(bin_items):
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ctx_len = len(c)
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start = len(seq_ids)
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item_len = len(c) + len(r)
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seq_ids.extend(c)
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seq_ids.extend(r)
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end = len(seq_ids)
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global_pos.extend(range(item_len))
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doc_ids.extend([di] * item_len)
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doc_offsets.append((start, end, orig_idx, ctx_len))
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full_ids = torch.tensor([seq_ids], device=device, dtype=torch.long)
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pos_ids = torch.tensor([global_pos], device=device, dtype=torch.long)
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seq_len = len(seq_ids)
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causal = torch.tril(
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torch.ones(seq_len, seq_len, dtype=torch.bool, device=device)
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)
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doc_t = torch.tensor([doc_ids], device=device)
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doc_mask = doc_t.unsqueeze(-1) == doc_t.unsqueeze(-2)
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attn_mask = (causal & doc_mask[0]).unsqueeze(0).unsqueeze(0)
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logits_full = model(full_ids, position_ids=pos_ids, input_mask=attn_mask)[
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"logits"
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][0]
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for start, end, orig_idx, ctx_len in doc_offsets:
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rl = end - start - ctx_len
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resp_start = start + ctx_len - 1
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resp_logits = logits_full[resp_start : end - 1]
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resp_targets = torch.tensor(
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seq_ids[start + ctx_len : end], device=device, dtype=torch.long
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)
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cond_losses = F.cross_entropy(
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resp_logits, resp_targets, reduction="none"
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).cpu()
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result[orig_idx] = {
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"_cond_losses": cond_losses,
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"_rl": rl,
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"_ctx_len": ctx_len,
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}
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# ---- unconditional pass (sentinel-prefixed, batched 2D) ----
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valid_items = [
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(
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i,
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result[i]["_rl"],
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result[i]["_ctx_len"],
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result[i]["_cond_losses"],
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pairs[i][1],
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)
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for i in range(len(pairs))
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if result[i] is not None and "_cond_losses" in result[i]
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]
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if not valid_items:
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return result
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valid_items.sort(key=lambda x: -x[1])
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prefix_len = len(sentinel_ids)
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max_rl = prefix_len + max(rl for _, rl, _, _, _ in valid_items)
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bsz = len(valid_items)
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u_batch = torch.zeros(bsz, max_rl, dtype=torch.long, device=device)
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for ri, (_, rl, _, _, r_ids) in enumerate(valid_items):
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u_batch[ri, :prefix_len] = torch.tensor(sentinel_ids, dtype=torch.long)
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u_batch[ri, prefix_len : prefix_len + rl] = torch.tensor(
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r_ids, dtype=torch.long
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)
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logits_resp = model(u_batch)["logits"]
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for ri, (orig_idx, rl, ctx_len, cond_losses, _) in enumerate(valid_items):
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unp_logits = logits_resp[ri, prefix_len - 1 : prefix_len - 1 + rl]
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unp_targets = u_batch[ri, prefix_len : prefix_len + rl]
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uncond_losses = F.cross_entropy(unp_logits, unp_targets, reduction="none").cpu()
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L_cond = cond_losses.mean().item()
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L_uncond = uncond_losses.mean().item()
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ifd = L_cond / L_uncond if L_uncond > 0 else None
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out = {
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"L_cond": round(L_cond, 6),
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"L_uncond": round(L_uncond, 6),
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"ifd": round(ifd, 6) if ifd is not None else None,
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"ctx_len": ctx_len,
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"resp_len": rl,
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}
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if per_token:
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per = [
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(round(c.item() / u.item(), 6) if u.item() > 0 else None)
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for c, u in zip(cond_losses, uncond_losses)
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]
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out["ifd_per_token"] = per
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result[orig_idx] = out
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return result
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def _trim(context_ids, resp_ids, max_len):
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"""Truncate to fit max_len, keeping response intact if possible."""
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if len(resp_ids) > max_len // 2:
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resp_ids = resp_ids[: max_len // 2]
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full_ids = context_ids + resp_ids
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if len(full_ids) <= max_len:
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return context_ids, resp_ids
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overflow = len(full_ids) - max_len
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if overflow >= len(context_ids):
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return [], resp_ids[:max_len]
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return context_ids[overflow:], resp_ids
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def score_plain(
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model,
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tokenizer,
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instruction,
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response,
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device,
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max_len=2048,
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sentinel_ids=None,
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per_token=False,
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):
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"""Compute IFD for a single instruction-response pair (plain format)."""
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ctx_ids = tokenizer.encode(instruction, add_special_tokens=False)
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resp_ids = tokenizer.encode(response, add_special_tokens=False)
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ctx_ids, resp_ids = _trim(ctx_ids, resp_ids, max_len)
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if not ctx_ids or not resp_ids:
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return {
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"L_cond": None,
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"L_uncond": None,
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"ifd": None,
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"skip_reason": "empty ctx or resp",
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}
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return _score_batch(
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[(ctx_ids, resp_ids)],
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model,
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device,
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max_len,
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sentinel_ids=sentinel_ids,
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per_token=per_token,
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)[0]
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def score_messages(
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model, tokenizer, messages, device, max_len=2048, sentinel_ids=None, per_token=False
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):
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"""Compute IFD for each assistant turn in a messages array."""
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turns = []
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for i, msg in enumerate(messages):
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if msg.get("role") != "assistant":
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continue
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ctx_text = "\n\n".join(m["content"] for m in messages[:i])
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ctx_ids = tokenizer.encode(ctx_text)
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resp_ids = tokenizer.encode(msg["content"], add_special_tokens=False)
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ctx_ids, resp_ids = _trim(ctx_ids, resp_ids, max_len)
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if ctx_ids and resp_ids:
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turns.append((ctx_ids, resp_ids))
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if not turns:
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return None
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raw_scores = _score_batch(
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turns, model, device, max_len, sentinel_ids=sentinel_ids, per_token=per_token
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)
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valid = [s for s in raw_scores if s is not None and s.get("ifd") is not None]
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if not valid:
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return {"ifd": None, "ifd_turns": raw_scores}
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avg = sum(s["ifd"] for s in valid) / len(valid)
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return {
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"ifd": avg,
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"ifd_detail": valid[0] if len(valid) == 1 else None,
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"ifd_turns": raw_scores,
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}
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def process_file(
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param_path,
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input_file,
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output_file,
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instr_key,
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resp_key,
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max_len=2048,
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data_format="plain",
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batch_size=1,
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device=None,
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sentinel_text="\n",
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per_token=False,
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):
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if device is None:
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device = "cuda" if torch.cuda.is_available() else "cpu"
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dtype = torch.bfloat16 if "cuda" in device else torch.float32
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model = AutoModel.from_pretrained(param_path)
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tokenizer = AutoTokenizer.from_pretrained(param_path)
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model.to(device=device, dtype=dtype)
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model.eval()
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sentinel_ids = _resolve_sentinel_ids(tokenizer, sentinel_text)
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with open(input_file, encoding="utf-8") as f:
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data = [json.loads(line) for line in f if line.strip()]
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results = []
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all_ifds = []
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buffer = []
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for item in tqdm.tqdm(data, desc="Computing IFD", unit="sample"):
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if data_format == "messages":
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turns = []
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for i, msg in enumerate(item.get("messages", [])):
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if msg.get("role") != "assistant":
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continue
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ctx_text = "\n\n".join(m["content"] for m in item["messages"][:i])
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ctx_ids = tokenizer.encode(ctx_text)
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resp_ids = tokenizer.encode(msg["content"], add_special_tokens=False)
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ctx_ids, resp_ids = _trim(ctx_ids, resp_ids, max_len)
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if ctx_ids and resp_ids:
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turns.append((ctx_ids, resp_ids))
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if not turns:
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results.append(
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{
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**item,
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"ifd": None,
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"skip_reason": "no valid assistant turns",
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"ifd_turns": [],
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}
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)
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continue
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buffer.append((item, turns, "messages"))
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else:
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ctx_ids = tokenizer.encode(item[instr_key], add_special_tokens=False)
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resp_ids = tokenizer.encode(item[resp_key], add_special_tokens=False)
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ctx_ids, resp_ids = _trim(ctx_ids, resp_ids, max_len)
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if not ctx_ids or not resp_ids:
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results.append(
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{
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**item,
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"ifd": None,
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"ifd_detail": {"skip_reason": "empty ctx or resp"},
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}
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)
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continue
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buffer.append((item, [(ctx_ids, resp_ids)], "plain"))
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if len(buffer) >= batch_size:
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_flush_buffer(
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buffer,
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results,
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all_ifds,
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model,
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device,
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max_len,
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sentinel_ids,
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per_token,
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)
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if buffer:
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_flush_buffer(
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buffer, results, all_ifds, model, device, max_len, sentinel_ids, per_token
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)
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with open(output_file, "w", encoding="utf-8") as f:
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for item in results:
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f.write(json.dumps(item, ensure_ascii=False) + "\n")
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valid_ifd = [v for v in all_ifds if v is not None]
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if valid_ifd:
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print(f"\n{'=' * 50}")
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print(f" Samples: {len(data)}")
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print(f" Valid IFD: {len(valid_ifd)}")
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print(f" Skipped: {len(data) - len(valid_ifd)}")
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print(f" Mean IFD: {statistics.mean(valid_ifd):.4f}")
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print(f" Median IFD: {statistics.median(valid_ifd):.4f}")
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if len(valid_ifd) > 1:
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print(f" Stdev IFD: {statistics.stdev(valid_ifd):.4f}")
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print(f" Min IFD: {min(valid_ifd):.4f}")
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print(f" Max IFD: {max(valid_ifd):.4f}")
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print(f"{'=' * 50}")
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print(f"Results saved to {output_file}")
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def _flush_buffer(
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buffer, results, all_ifds, model, device, max_len, sentinel_ids, per_token
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):
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all_pairs = []
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indices = []
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for item, turns, fmt in buffer:
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start = len(all_pairs)
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all_pairs.extend(turns)
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indices.append((item, turns, fmt, start, len(all_pairs)))
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raw = _score_batch(
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all_pairs,
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model,
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device,
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max_len,
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sentinel_ids=sentinel_ids,
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per_token=per_token,
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)
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for item, turns, fmt, start, end in indices:
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turn_scores = raw[start:end]
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if fmt == "messages":
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valid = [
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s for s in turn_scores if s is not None and s.get("ifd") is not None
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]
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if not valid:
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results.append({**item, "ifd": None, "ifd_turns": turn_scores})
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else:
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avg = sum(s["ifd"] for s in valid) / len(valid)
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all_ifds.append(avg)
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results.append(
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{
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**item,
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"ifd": avg,
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"ifd_detail": valid[0] if len(valid) == 1 else None,
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"ifd_turns": turn_scores,
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}
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)
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else:
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score = turn_scores[0]
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all_ifds.append(score.get("ifd"))
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results.append({**item, "ifd": score.get("ifd"), "ifd_detail": score})
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buffer.clear()
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def main():
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parser = argparse.ArgumentParser(
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description="Compute IFD scores for instruction-response data"
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)
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parser.add_argument("--param_path", type=str, required=True, help="Model directory")
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parser.add_argument("--input", type=str, required=True, help="Input JSONL file")
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parser.add_argument("--output", type=str, required=True, help="Output JSONL file")
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parser.add_argument("--max_len", type=int, default=2048, help="Max token length")
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parser.add_argument(
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"--format",
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type=str,
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default="plain",
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choices=["plain", "messages"],
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help="Input format",
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)
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parser.add_argument(
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"--instr_key", type=str, default="instruction", help="Key for instruction field"
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)
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parser.add_argument(
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"--resp_key", type=str, default="response", help="Key for response field"
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)
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parser.add_argument(
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"--batch_size", type=int, default=8, help="Batch size for model forward passes"
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)
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parser.add_argument("--device", type=str, default=None, help="Device (e.g. cuda:0)")
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parser.add_argument(
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"--sentinel_text",
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type=str,
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default="\n",
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help='Plain-text prefix for unconditional pass (default: "\\n"). Use "" for bos/pad fallback.',
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)
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parser.add_argument(
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"--per_token",
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action="store_true",
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help="Include per-token IFD breakdown in output",
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)
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args = parser.parse_args()
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process_file(
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args.param_path,
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args.input,
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args.output,
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args.instr_key,
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args.resp_key,
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args.max_len,
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data_format=args.format,
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batch_size=args.batch_size,
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device=args.device,
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sentinel_text=args.sentinel_text,
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per_token=args.per_token,
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)
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if __name__ == "__main__":
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main()
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