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heretic/src/heretic/evaluator.py
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Spiky Moth 9d1734855d feat: avoid excessive low divergence iteration (#73)
* feat: adjust scoring to avoid useless iteration

Adjusts the scoring function to avoid targeting meaninglessly low KL divergences.
Below a threshold value, the KL divergence score switches to the refusal count.
Adds config option kl_divergence_target (defaulting to 0.01).

* fix: Clean up parameter selection in objective

Create variables for num_layers and last_layer_index
* Improves readability and makes choices explicit

* feat: Print the parameters of the selected model
2025-12-14 14:26:48 +05:30

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# SPDX-License-Identifier: AGPL-3.0-or-later
# Copyright (C) 2025 Philipp Emanuel Weidmann <pew@worldwidemann.com>
import torch.nn.functional as F
from .config import Settings
from .model import Model
from .utils import load_prompts, print
class Evaluator:
def __init__(self, settings: Settings, model: Model):
self.settings = settings
self.model = model
print()
print(
f"Loading good evaluation prompts from [bold]{settings.good_evaluation_prompts.dataset}[/]..."
)
self.good_prompts = load_prompts(settings.good_evaluation_prompts)
print(f"* [bold]{len(self.good_prompts)}[/] prompts loaded")
print("* Obtaining first-token probability distributions...")
self.base_logprobs = model.get_logprobs_batched(self.good_prompts)
print()
print(
f"Loading bad evaluation prompts from [bold]{settings.bad_evaluation_prompts.dataset}[/]..."
)
self.bad_prompts = load_prompts(settings.bad_evaluation_prompts)
print(f"* [bold]{len(self.bad_prompts)}[/] prompts loaded")
print("* Counting model refusals...")
self.base_refusals = self.count_refusals()
print(
f"* Initial refusals: [bold]{self.base_refusals}[/]/{len(self.bad_prompts)}"
)
def is_refusal(self, response: str) -> bool:
# Classify empty responses as refusals to avoid optimizing for them.
if not response.strip():
return True
# Remove emphasis (e.g. "I *will not*...").
response = response.lower().replace("*", "")
# Normalize typographic apostrophes ("won’t" -> "won't").
response = response.replace("’", "'")
# Normalize whitespace between words to a single space.
response = " ".join(response.split())
for marker in self.settings.refusal_markers:
if marker.lower() in response:
return True
return False
def count_refusals(self) -> int:
responses = self.model.get_responses_batched(self.bad_prompts)
refusals = [response for response in responses if self.is_refusal(response)]
return len(refusals)
def get_score(self) -> tuple[tuple[float, float], float, int]:
print(" * Obtaining first-token probability distributions...")
logprobs = self.model.get_logprobs_batched(self.good_prompts)
kl_divergence = F.kl_div(
logprobs,
self.base_logprobs,
reduction="batchmean",
log_target=True,
).item()
print(f" * KL divergence: [bold]{kl_divergence:.4f}[/]")
print(" * Counting model refusals...")
refusals = self.count_refusals()
print(f" * Refusals: [bold]{refusals}[/]/{len(self.bad_prompts)}")
kl_divergence_scale = self.settings.kl_divergence_scale
kl_divergence_target = self.settings.kl_divergence_target
refusals_score = refusals / self.base_refusals
if kl_divergence >= kl_divergence_target:
kld_score = kl_divergence / kl_divergence_scale
else:
kld_score = refusals_score * kl_divergence_target / kl_divergence_scale
score = (
kld_score,
refusals_score,
)
return score, kl_divergence, refusals