Files
mlx-lm/tests/test_sample_utils.py
Dirky 9df9689fdc Adding support for XTC (eXclude Top Choice) (#110)
* feat: Added XTC logit processor

* feat: Excluding newline/EOS chars from XTC

* fix: Avoiding non-vectorized operation

* feat: Moved XTC to samplers + correcting threshold allowed range

* feat: Added XTC sampler to mlx_lm.chat and mlx_lm.generate

* test: Adding test for apply_xtc

* test: Updated test to match the new XTC behavior

* feat: Simplified XTC implementation

* feat: XTC special tokens exclusion simplification

* fix: Corrected wrong compare for xtc_probability and threshold verif in server

* test: Resetting probs and logprobs to avoid failures in CI

* Fix tests

* Change the special tokens name a bit

* Fix it in mlx_lm.server

---------

Co-authored-by: Dirky <dirky@dirky.fr>
Co-authored-by: Angelos Katharopoulos <a_katharopoulos@apple.com>
2025-04-24 14:25:30 -07:00

122 lines
4.6 KiB
Python

import unittest
import mlx.core as mx
from mlx_lm.sample_utils import apply_min_p, apply_top_k, apply_top_p, apply_xtc
class TestSampleUtils(unittest.TestCase):
def test_apply_top_p(self):
probs = mx.array([0.9, 0.0, 0.0, 0.1])[None]
logits = mx.log(probs)
new_logits = apply_top_p(logits, 0.3)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertEqual(actual_probs.tolist(), [1.0, 0.0, 0.0, 0.0])
new_logits = apply_top_p(logits, 0.95)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertTrue(mx.allclose(probs.squeeze(), actual_probs))
probs = mx.array([0.0, 0.5, 0.4, 0.1])[None]
logits = mx.log(probs)
new_logits = apply_top_p(logits, 0.4)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertEqual(actual_probs.tolist(), [0.0, 1.0, 0.0, 0.0])
new_logits = apply_top_p(logits, 0.6)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertEqual(
[round(p, 4) for p in actual_probs.tolist()], [0.0, 0.5556, 0.4444, 0.0]
)
new_logits = apply_top_p(logits, 0.95)
actual_probs = mx.softmax(new_logits.squeeze())
actual_rounded = [round(p, 4) for p in actual_probs.tolist()]
expected_rounded = [0.0, 0.5, 0.4, 0.1]
self.assertEqual(actual_rounded, expected_rounded)
self.assertAlmostEqual(sum(actual_probs.tolist()), 1.0)
# Batch mode works
probs = mx.array([[0.9, 0.0, 0.0, 0.1], [0.0, 0.8, 0.1, 0.1]])
logits = mx.log(probs)
new_logits = apply_top_p(logits, 0.5)
actual_probs = mx.softmax(new_logits, axis=-1)
self.assertEqual(
actual_probs.tolist(), [[1.0, 0.0, 0.0, 0.0], [0.0, 1.0, 0.0, 0.0]]
)
def test_apply_min_p(self):
probs = mx.array([0.9, 0.0, 0.0, 0.1])[None]
logits = mx.log(probs)
new_logits = apply_min_p(logits, 0.8)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertEqual(actual_probs.tolist(), [1.0, 0.0, 0.0, 0.0])
probs = mx.array([0.9, 0.0, 0.0, 0.1])[None]
logits = mx.log(probs)
new_logits = apply_min_p(logits, 0.05)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertTrue(mx.allclose(actual_probs, mx.squeeze(probs)))
# Batch mode works
probs = mx.array([[0.9, 0.0, 0.0, 0.1], [0.0, 0.8, 0.0, 0.1]])
logits = mx.log(probs)
new_logits = apply_min_p(logits, 0.7)
actual_probs = mx.softmax(new_logits, axis=-1)
self.assertEqual(
actual_probs.tolist(), [[1.0, 0.0, 0.0, 0.0], [0.0, 1.0, 0.0, 0.0]]
)
def test_apply_top_k(self):
probs = mx.array([0.9, 0.0, 0.0, 0.1])[None]
logits = mx.log(probs)
new_logits = apply_top_k(logits, 1)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertEqual(actual_probs.tolist(), [1.0, 0.0, 0.0, 0.0])
probs = mx.array([0.6, 0.0, 0.1, 0.3])[None]
logits = mx.log(probs)
new_logits = apply_top_k(logits, 2)
actual_probs = mx.softmax(new_logits.squeeze())
self.assertEqual(
[round(p, 4) for p in actual_probs.tolist()], [0.6667, 0.0, 0.0, 0.3333]
)
# Batch mode works
probs = mx.array([[0.9, 0.0, 0.0, 0.1], [0.0, 0.8, 0.0, 0.1]])
logits = mx.log(probs)
new_logits = apply_top_k(logits, 1)
actual_probs = mx.softmax(new_logits, axis=-1)
self.assertEqual(
actual_probs.tolist(), [[1.0, 0.0, 0.0, 0.0], [0.0, 1.0, 0.0, 0.0]]
)
def test_apply_xtc(self):
# Test the threshold
probs = mx.array([[0.4, 0.3, 0.15, 0.15]])
new_probs = mx.softmax(apply_xtc(mx.log(probs), 1, 0.2, []), -1)
expected = mx.array([[0, 0.5, 0.25, 0.25]])
self.assertTrue(mx.allclose(new_probs, expected))
probs = mx.array([[0.4, 0.3, 0.15, 0.15]])
new_probs = mx.softmax(apply_xtc(mx.log(probs), 1, 0.1, []), -1)
expected = mx.array([[0, 0.0, 0.5, 0.5]])
self.assertTrue(mx.allclose(new_probs, expected))
# Test the special tokens
probs = mx.array([[0.4, 0.3, 0.15, 0.15]])
new_probs = mx.softmax(apply_xtc(mx.log(probs), 1, 0.1, [0]), -1)
expected = mx.array([[4 / 7, 0.0, 1.5 / 7, 1.5 / 7]])
self.assertTrue(mx.allclose(new_probs, expected))
# Test that with probability 0 the probs don't change
probs = mx.array([[0.4, 0.3, 0.15, 0.15]])
new_probs = mx.softmax(apply_xtc(mx.log(probs), 0, 0.1, [0]), -1)
self.assertTrue(mx.allclose(new_probs, probs))
if __name__ == "__main__":
unittest.main()