refactor: update evaluation metrics to include pmass_allowed and nll_json

This commit is contained in:
wassname
2026-05-21 06:05:16 +00:00
parent ef20a83504
commit 49751fbeab
5 changed files with 160 additions and 63 deletions
+18 -9
View File
@@ -167,10 +167,10 @@ def evaluate(
Returns:
Dict with `table`, `profile`, `mean_js`, `mean_nll`, `mean_nll_T`,
`median_nll_T`, `T`, `top1_acc`, `mean_pmass_format`, and `info`.
`median_nll_T`, `T`, `top1_acc`, `mean_pmass_allowed`, `mean_nll_json`, and `info`.
With `return_per_row=True`, also includes `per_row` with per-row
`p`, `score` (debiased logp per foundation), `pmass_format`,
`gen_text` / `gen_text_rev` (full decoded gen, no stripping),
`p`, `score` (debiased logp per foundation), `pmass_allowed`,
`nll_json`, `gen_text` / `gen_text_rev` (full decoded gen, no stripping),
and `top1` / `margin`.
"""
if vignettes is None:
@@ -218,7 +218,8 @@ def evaluate(
"label": label, # may be None on unlabeled rows
"top1": res.top1,
"margin": res.margin,
"pmass_format": res.pmass_format,
"pmass_allowed": res.pmass_allowed,
"nll_json": res.nll_json,
"think_tokens": res.think_tokens, # list[int], length N
"think_tokens_rev": res.think_tokens_rev, # list[int], length N
"emitted_close": res.emitted_close, # list[bool], length N
@@ -327,8 +328,12 @@ def evaluate(
T = None
profile = None
mean_pmass_format = (
float(np.mean([r["pmass_format"] for r in per_row]))
mean_pmass_allowed = (
float(np.mean([r["pmass_allowed"] for r in per_row]))
if per_row else None
)
mean_nll_json = (
float(np.mean([r["nll_json"] for r in per_row]))
if per_row else None
)
info = {
@@ -341,13 +346,16 @@ def evaluate(
"mean_nll": mean_nll,
"median_nll": median_nll,
"median_nll_T": median_nll_T,
# Mean pmass_format: average prob mass on the K foundation answer
# Mean pmass_allowed: average prob mass on the K foundation answer
# tokens at the JSON answer slot, across rows × framings. In [0, 1].
# Direct coherence canary for forced-choice — drops when the model
# emits non-foundation tokens (gibberish, refusal, format collapse),
# independent of which foundation is picked. Higher = more
# "in-format"; a sharp drop after steering signals coherence loss.
"mean_pmass_format": mean_pmass_format,
"mean_pmass_allowed": mean_pmass_allowed,
# Mean NLL in nats/token over the assistant prefill content. Perplexity
# is exp(mean_nll_json).
"mean_nll_json": mean_nll_json,
}
out: dict[str, Any] = {
@@ -359,7 +367,8 @@ def evaluate(
"median_nll_T": median_nll_T,
"T": T, # fitted temperature (>1 = model is overconfident)
"top1_acc": top1_acc,
"mean_pmass_format": mean_pmass_format,
"mean_pmass_allowed": mean_pmass_allowed,
"mean_nll_json": mean_nll_json,
"info": info,
}
if return_per_row:
+78 -36
View File
@@ -10,8 +10,8 @@ suffix's last position, gathers logprobs at the foundation first-tokens.
Why per-sample rewind: HF generate() with a batch stops each sample at its
own EOS but keeps the cache full-length (pad-filled after stop). If we just
appended a batched suffix at J_max, the suffix's position embeddings would
land far past the model's actual stopping point, polluting the pmass
appended a batched suffix at J_max, the suffix's position embeddings would
land far past the model's actual stopping point, polluting `pmass_allowed`
measurement with post-EOS context. Per-sample slicing puts the suffix
immediately after each sample's real content.
@@ -100,7 +100,7 @@ def _rollout_kv_fork(
layout in `thinks` and `slots`. Caller reshapes via `[i*N + n]` indexing.
thinks[j] = (gen_text, n_think_tokens, emitted_close), j in [0, B*N).
slots[j][k] = {pmass_format, top5_str, lp_gather}, j in [0, B*N).
slots[j][k] = {pmass_allowed, nll_json, top5_str, lp_gather}, j in [0, B*N).
Three-phase rollout:
Phase 1 (batched) — generate up to max_think_tokens with cache=True,
@@ -113,7 +113,8 @@ def _rollout_kv_fork(
Phase 2 (per-sample) — forward the scoring suffix with rewound pkv,
read logits at the suffix's last position.
`pmass_format` is Σ exp(logp) over `gather_token_ids` at the slot.
`pmass_allowed` is Σ exp(logp) over `gather_token_ids` at the slot.
`nll_json` is mean NLL in nats/token over the assistant prefill tokens.
`lp_gather` is the per-id logp vector at the slot.
"""
if tok.padding_side != "left":
@@ -182,7 +183,7 @@ def _rollout_kv_fork(
# Phase 1.5: rewind position = first think_end_id in gen (inclusive),
# so the answer slot's KV context ends at the natural stopping point —
# not at the post-EOS spew (which would corrupt pmass).
# not at the post-EOS spew (which would corrupt `pmass_allowed`).
eos_mask = (gen_ids_full == think_end_id)
if eos_mask.any():
first_eos = int(eos_mask.nonzero(as_tuple=True)[0][0].item())
@@ -196,25 +197,34 @@ def _rollout_kv_fork(
# === Phase 2: per-sample suffix forward over rewound pkv ===
gid_t = torch.tensor(gather_token_ids, device=device, dtype=torch.long)
def suf_ids_for(nudge: str, prefill: str) -> list[list[int]]:
"""Per-row suffix: optional </think> close + assistant-turn close +
interrupt-and-renudge (user(nudge) + assistant(prefill))."""
def suffix_parts_for(nudge: str, prefill: str) -> list[tuple[list[int], list[int]]]:
"""Per-row suffix parts: optional </think> close + assistant-turn close +
interrupt-and-renudge prefix, then assistant prefill content.
Split before tokenization so `nll_json` scores exactly the assistant
prefill content, while the final logits still come after the prefill.
"""
interrupt = tok.apply_chat_template(
[{"role": "user", "content": nudge},
{"role": "assistant", "content": prefill}],
{"role": "assistant", "content": _ASSISTANT_SENTINEL}],
tokenize=False, continue_final_message=True,
)
suffixes = []
assert _ASSISTANT_SENTINEL in interrupt, f"sentinel not in interrupt: {interrupt!r}"
interrupt_prefix = interrupt.split(_ASSISTANT_SENTINEL, 1)[0]
prefill_ids = tok(prefill, add_special_tokens=False)["input_ids"]
assert prefill_ids, f"empty prefill ids for {prefill!r}"
suffix_parts = []
for _, _, emitted_close in thinks:
head = "" if emitted_close else _CLOSE_MARKER
suf_text = head + close + interrupt
suffixes.append(tok(suf_text, add_special_tokens=False)["input_ids"])
return suffixes
prefix_text = head + close + interrupt_prefix
prefix_ids = tok(prefix_text, add_special_tokens=False)["input_ids"]
suffix_parts.append((prefix_ids, prefill_ids))
return suffix_parts
def fork_per_sample(suffixes: list[list[int]]) -> torch.Tensor:
def fork_per_sample(suffix_parts: list[tuple[list[int], list[int]]]) -> tuple[torch.Tensor, torch.Tensor]:
"""Per-sample forward: rewind pkv to first-EOS for each sample,
forward only that sample's suffix, return [B, V] logp at the suffix's
last position.
forward that sample's interrupt prefix and assistant prefill, return
[B, V] logp at the answer slot plus per-sample prefill NLL.
Per-sample (bs=1) because each sample's rewind position differs;
batching would require padding pkv along seq_len with attention-mask
@@ -223,34 +233,57 @@ def _rollout_kv_fork(
"""
V = model.config.vocab_size
lp_last = torch.zeros((B, V), device=device, dtype=torch.float32)
nll_json = torch.zeros((B,), device=device, dtype=torch.float32)
for i in range(B):
end_pos = real_lens[i]
pkv_i = _slice_pkv_one(pkv, i, end_pos)
pref_attn_i = pref_attn[i:i+1, :end_pos]
suf_i = torch.tensor([suffixes[i]], device=device, dtype=torch.long)
L = suf_i.shape[1]
suf_mask_i = torch.ones((1, L), dtype=torch.long, device=device)
full_attn_i = torch.cat([pref_attn_i, suf_mask_i], dim=1)
out = model(
input_ids=suf_i,
attention_mask=full_attn_i,
prefix_ids, prefill_ids = suffix_parts[i]
prefix_i = torch.tensor([prefix_ids], device=device, dtype=torch.long)
prefill_i = torch.tensor([prefill_ids], device=device, dtype=torch.long)
P = prefix_i.shape[1]
J = prefill_i.shape[1]
prefix_mask_i = torch.ones((1, P), dtype=torch.long, device=device)
prefix_attn_i = torch.cat([pref_attn_i, prefix_mask_i], dim=1)
prefix_out = model(
input_ids=prefix_i,
attention_mask=prefix_attn_i,
past_key_values=pkv_i,
use_cache=True,
)
prefill_mask_i = torch.ones((1, J), dtype=torch.long, device=device)
prefill_attn_i = torch.cat([prefix_attn_i, prefill_mask_i], dim=1)
prefill_out = model(
input_ids=prefill_i,
attention_mask=prefill_attn_i,
past_key_values=prefix_out.past_key_values,
use_cache=False,
)
lp_last[i] = F.log_softmax(out.logits[0, -1].float(), dim=-1)
return lp_last
first_logp = F.log_softmax(prefix_out.logits[0, -1].float(), dim=-1)
first_nll = -first_logp[prefill_i[0, 0]]
if J == 1:
total_nll = first_nll
else:
next_logp = F.log_softmax(prefill_out.logits[0, :-1].float(), dim=-1)
next_ids = prefill_i[0, 1:]
total_nll = first_nll - next_logp.gather(1, next_ids[:, None]).sum()
nll_json[i] = total_nll / J
lp_last[i] = F.log_softmax(prefill_out.logits[0, -1].float(), dim=-1)
return lp_last, nll_json
slots: list[list[dict]] = [[] for _ in range(B)]
for j, (nudge, prefill) in enumerate(scoring_slots):
suf_ids = suf_ids_for(nudge, prefill)
suffix_parts = suffix_parts_for(nudge, prefill)
if verbose:
# DEBUG: shows row 0 only. Independent generate from raw ids
# (does not use the cache) so it still works after the rewind.
real0 = phase1_ids[0][phase1_ids[0] != pad_id]
prefix_text = tok.decode(real0, skip_special_tokens=False)
suf_text_0 = tok.decode(suf_ids[0], skip_special_tokens=False)
suf_text_0 = tok.decode(suffix_parts[0][0] + suffix_parts[0][1], skip_special_tokens=False)
full_ids = torch.tensor(
[real0.tolist() + suf_ids[0]], device=device, dtype=torch.long,
[real0.tolist() + suffix_parts[0][0] + suffix_parts[0][1]], device=device, dtype=torch.long,
)
gen = model.generate(full_ids, max_new_tokens=64, do_sample=False, pad_token_id=pad_id)
free = tok.decode(gen[0, full_ids.shape[1]:], skip_special_tokens=False)
@@ -258,8 +291,8 @@ def _rollout_kv_fork(
f"--- slot {j} (nudge={nudge!r}, prefill={prefill!r}) ---\n"
f"{prefix_text}{suf_text_0}<<<MODEL CONTINUES>>>{free}\n--- end slot {j} ---"
)
lp_last = fork_per_sample(suf_ids)
pmass = lp_last[:, gid_t].exp().sum(-1)
lp_last, nll_json = fork_per_sample(suffix_parts)
pmass_allowed = lp_last[:, gid_t].exp().sum(-1)
for i in range(B):
top5 = lp_last[i].topk(5)
top5_str = " ".join(
@@ -267,7 +300,8 @@ def _rollout_kv_fork(
for idx, prob in zip(top5.indices, top5.values)
)
slots[i].append({
"pmass_format": float(pmass[i].item()),
"pmass_allowed": float(pmass_allowed[i].item()),
"nll_json": float(nll_json[i].item()),
"top5_str": top5_str,
"lp_gather": lp_last[i, gid_t].cpu().tolist(),
})
@@ -368,7 +402,11 @@ class ForcedChoiceResult:
# leaked to other tokens (gibberish, refusal, format collapse). Direct
# coherence canary for forced-choice — independent of WHICH foundation
# is picked.
pmass_format: float
pmass_allowed: float
# Mean negative log-likelihood in nats/token over the assistant prefill
# content, averaged across samples and fwd + rev framings. Perplexity is
# `exp(nll_json)`.
nll_json: float
def _resolve_first_token_ids(tok, words: list[str]) -> tuple[list[int], dict[str, int]]:
@@ -511,11 +549,14 @@ def guided_rollout_forced_choice(
order_sorted = sorted(range(K), key=lambda k: -score[k])
top1 = foundations[order_sorted[0]]
margin = score[order_sorted[0]] - score[order_sorted[1]]
# Average pmass_format across N samples per direction, then across
# Average pmass_allowed and nll_json across N samples per direction, then across
# fwd + rev framings.
pm_f = sum(slots_fwd[j][0]["pmass_format"] for j in idx) / N
pm_r = sum(slots_rev[j][0]["pmass_format"] for j in idx) / N
pm_f = sum(slots_fwd[j][0]["pmass_allowed"] for j in idx) / N
pm_r = sum(slots_rev[j][0]["pmass_allowed"] for j in idx) / N
pm = 0.5 * (pm_f + pm_r)
nll_f = sum(slots_fwd[j][0]["nll_json"] for j in idx) / N
nll_r = sum(slots_rev[j][0]["nll_json"] for j in idx) / N
nll_json = 0.5 * (nll_f + nll_r)
results.append(ForcedChoiceResult(
user_prompt=user_prompts[i],
gen_text=gens_fwd,
@@ -532,7 +573,8 @@ def guided_rollout_forced_choice(
think_tokens_rev=n_rev_list,
emitted_close=close_fwd_list,
emitted_close_rev=close_rev_list,
pmass_format=float(pm),
pmass_allowed=float(pm),
nll_json=float(nll_json),
))
return results