unsloth/tests/utils/perplexity_eval.py
Daniel Han a6dc10dad2
Reduce and tighten comments and docstrings across the test suite (#6429)
* Reduce and tighten comments and docstrings in tests

Shorten verbose comments and docstrings across the test suite without
changing any test logic. Remove narration that restates the next line,
collapse long module and test docstrings to a single line, and drop banner
separators. Keep regression context (issue and PR references, run ids),
skip reasons, mocking and timing rationale, license headers, lint and type
directives, and commented-out code.

Comments and docstrings only: an AST signature check confirms no code,
assertions, or string literals changed, and the suite byte-compiles cleanly.

* [pre-commit.ci] auto fixes from pre-commit.com hooks

for more information, see https://pre-commit.ci

---------

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
2026-06-18 01:07:09 -07:00

64 lines
2.2 KiB
Python

from tqdm import tqdm
import torch
import pandas as pd
model_comparison_results = {}
# Per-example perplexity, sliding window for examples longer than 512 tokens.
def ppl_model(model, tokenizer, dataset):
nlls = []
max_length = 2048
stride = 512
for s in tqdm(range(len(dataset["text"]))):
encodings = tokenizer(dataset["text"][s], return_tensors = "pt")
seq_len = encodings.input_ids.size(1)
prev_end_loc = 0
for begin_loc in range(0, seq_len, stride):
end_loc = min(begin_loc + max_length, seq_len)
trg_len = end_loc - prev_end_loc
input_ids = encodings.input_ids[:, begin_loc:end_loc].to("cuda")
target_ids = input_ids.clone()
target_ids[:, :-trg_len] = -100
pad_token_id = tokenizer.pad_token_id if tokenizer.pad_token_id is not None else 0
attention_mask = (input_ids != pad_token_id).long()
with torch.no_grad():
outputs = model(input_ids, labels = target_ids, attention_mask = attention_mask)
neg_log_likelihood = outputs.loss
nlls.append(neg_log_likelihood)
prev_end_loc = end_loc
if end_loc == seq_len:
break
ppl = torch.exp(torch.stack(nlls).mean())
return ppl
# ----------- Reporting helpers ----------- #
def add_to_comparison(model_name, ppl):
"""Record a model's perplexity in the comparison tracker."""
model_comparison_results[model_name] = {"ppl": ppl}
def print_model_comparison():
"""Print a comparison of all models evaluated so far"""
if not model_comparison_results:
print("No model results available for comparison")
return
print("\n==== MODEL COMPARISON REPORT ====")
comparison_df = pd.DataFrame(
{
"Model": list(model_comparison_results.keys()),
"Perplexity": [
# Tensors to CPU float if needed.
results["ppl"].cpu().item() if torch.is_tensor(results["ppl"]) else results["ppl"]
for results in model_comparison_results.values()
],
}
)
print("\nComparison Table:")
print(comparison_df.to_string(index = False))