[BUG][Hidalgo] AssertionError: assert rmax > 0 #3068
Description
Describe the bug
I'm trying to use Hidalgo to segment our dataset, but I get an assert rmax > 0 error.
Steps/Code to reproduce the bug
import json
import pandas as pd
from aeon.segmentation import HidalgoSegmenter
from sklearn.preprocessing import MinMaxScaler
# Data subset
data_dict = json.loads('{"x":{"0":0.4257669507,"1":0.4253725033,"2":0.4252818198,"3":0.4252818198,"4":0.425349677,"5":0.4253740215,"6":0.4254784689,"7":0.4254784689,"8":0.4255383361,"9":0.4254318762,"10":0.4256996914,"11":0.4256130534,"12":0.4256130534,"13":0.4253865468,"14":0.4253865468,"15":0.4252407974,"16":0.4252407974,"17":0.4257405957,"18":0.4257405957,"19":0.4255358599,"20":0.4251156221,"21":0.4251156221,"22":0.4253575551,"23":0.4255880915,"24":0.4255663679,"25":0.4256628462,"26":0.4256628462,"27":0.4259410406,"28":0.4267114539,"29":0.4277039868,"30":0.4284604203,"31":0.4284604203,"32":0.4302800694,"33":0.4322460778,"34":0.4346705172,"35":0.4346705172,"36":0.4371808068,"37":0.4392193531,"38":0.4419787566,"39":0.44394467,"40":0.4455386315,"41":0.4455386315,"42":0.4484341572,"43":0.4507840657,"44":0.4507840657,"45":0.4532244633,"46":0.4549927733,"47":0.4576848292,"48":0.4610286743,"49":0.4663468167},"y":{"0":0.2433640871,"1":0.2433817587,"2":0.243515473,"3":0.243515473,"4":0.243330775,"5":0.2433764023,"6":0.2433758396,"7":0.2433758396,"8":0.2436249834,"9":0.2434208001,"10":0.2431829586,"11":0.243519011,"12":0.243519011,"13":0.2435338798,"14":0.2435338798,"15":0.2427958052,"16":0.2427958052,"17":0.2434832522,"18":0.2434832522,"19":0.243382383,"20":0.2433153482,"21":0.2433153482,"22":0.2434281222,"23":0.2436008387,"24":0.2429868484,"25":0.2437683391,"26":0.2437683391,"27":0.2439072948,"28":0.242919792,"29":0.2433073901,"30":0.2428429508,"31":0.2428429508,"32":0.2436557076,"33":0.2433159762,"34":0.2428919038,"35":0.2428919038,"36":0.2435177615,"37":0.2428567016,"38":0.2434209507,"39":0.2434055484,"40":0.2434657139,"41":0.2434657139,"42":0.2440847695,"43":0.2442286093,"44":0.2442286093,"45":0.2448578754,"46":0.2445213732,"47":0.2448515841,"48":0.2466578652,"49":0.2475578949},"z":{"0":0.9763806256,"1":0.976541671,"2":0.9766390753,"3":0.9766390753,"4":0.9761048068,"5":0.9765859558,"6":0.9765303357,"7":0.9765303357,"8":0.9765715424,"9":0.9762428674,"10":0.9767105624,"11":0.9763704237,"12":0.9763704237,"13":0.9764624393,"14":0.9764624393,"15":0.9762103707,"16":0.9762103707,"17":0.9764087797,"18":0.9764087797,"19":0.976436962,"20":0.9764482037,"21":0.9764482037,"22":0.9764192093,"23":0.9767144461,"24":0.9764186015,"25":0.9765317889,"26":0.9765317889,"27":0.9763026984,"28":0.9767263621,"29":0.9761456476,"30":0.9767367686,"31":0.9767367686,"32":0.976554542,"33":0.9760865449,"34":0.9762832482,"35":0.9762832482,"36":0.9763611054,"37":0.9761762628,"38":0.9762820997,"39":0.9757640754,"40":0.9758159129,"41":0.9758159129,"42":0.9757864022,"43":0.975320887,"44":0.975320887,"45":0.9757195712,"46":0.9755819628,"47":0.9758874947,"48":0.9760461699,"49":0.9754331639}}')
# Preprocess
X_df = pd.DataFrame(data_dict)
X_df_scaled = MinMaxScaler(feature_range=(0, 1)).fit_transform(X_df)
# Segmentation
hidalgo = HidalgoSegmenter(K=len(labels), q=3, n_iter=2000, burn_in=0.8)
cps = hidalgo.fit_predict(X_df_scaled, axis=0)
print("Found change points:", cps)Expected results
No error is thrown
Actual results
[/home/user/Projects/segmentation-baselines/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py:176](http://localhost:8889/lab/tree/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py#line=175): RuntimeWarning: divide by zero encountered in divide
mu = np.divide(distances[:, 2], distances[:, 1])
---------------------------------------------------------------------------
AssertionError Traceback (most recent call last)
Cell In[28], line 1
----> 1 cps = hidalgo.fit_predict(X_reduced_scaled, axis=0)
2 print("Found change points:", cps)
File [~/Projects/segmentation-baselines/venv/lib64/python3.11/site-packages/aeon/segmentation/base.py:160](http://localhost:8889/lab/tree/venv/lib64/python3.11/site-packages/aeon/segmentation/base.py#line=159), in BaseSegmenter.fit_predict(self, X, y, axis)
157 """Fit segmentation to data and return it."""
158 # Non-optimized default implementation; override when a better
159 # method is possible for a given algorithm.
--> 160 self.fit(X, y, axis=axis)
161 return self.predict(X, axis=axis)
File [~/Projects/segmentation-baselines/venv/lib64/python3.11/site-packages/aeon/segmentation/base.py:122](http://localhost:8889/lab/tree/venv/lib64/python3.11/site-packages/aeon/segmentation/base.py#line=121), in BaseSegmenter.fit(self, X, y, axis)
120 if y is not None:
121 y = self._check_y(y)
--> 122 self._fit(X=X, y=y)
123 self.is_fitted = True
124 return self
File [~/Projects/segmentation-baselines/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py:607](http://localhost:8889/lab/tree/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py#line=606), in HidalgoSegmenter._fit(self, X, y)
604 maxlik = -1e10
606 for _ in range(n_replicas):
--> 607 sampling = self._gibbs_sampling(
608 N,
609 mu,
610 Iin,
611 Iout,
612 Iout_count,
613 Iout_track,
614 V,
615 NN,
616 a1,
617 b1,
618 c1,
619 Z,
620 f1,
621 N_in,
622 _rng,
623 )
624 sampling = np.reshape(sampling, (n_iter, Npar))
626 idx = [
627 it
628 for it in range(n_iter)
629 if it % sampling_rate == 0 and it >= n_iter * burn_in
630 ]
File [~/Projects/segmentation-baselines/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py:514](http://localhost:8889/lab/tree/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py#line=513), in HidalgoSegmenter._gibbs_sampling(self, N, mu, Iin, Iout, Iout_count, Iout_track, V, NN, a1, b1, c1, Z, f1, N_in, _rng)
511 return lik0, lik1
513 for it in range(n_iter):
--> 514 d = sample_d(K, a1, b1, _rng)
515 sampling = np.append(sampling, d)
517 (p, pp) = sample_p(K, p, pp, c1, _rng)
File [~/Projects/segmentation-baselines/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py:343](http://localhost:8889/lab/tree/venv/lib64/python3.11/site-packages/aeon/segmentation/_hidalgo.py#line=342), in HidalgoSegmenter._gibbs_sampling.<locals>.sample_d(K, a1, b1, _rng)
340 rmax = (a1[k] - 1) [/](http://localhost:8889/) b1[k]
342 if a1[k] - 1 > 0:
--> 343 assert rmax > 0
344 frac = np.exp(
345 -b1[k] * (r1 - rmax)
346 - (a1[k] - 1) * (np.log(rmax) - np.log(r1))
347 )
348 else:
AssertionError:
Versions
System:
python: 3.11.13 (main, Jun 09 2025, 17:26:24) [GCC]
executable: /home/user/Projects/segmentation-baselines/venv/bin/python3.11
machine: Linux-6.15.8-1-default-x86_64-with-glibc2.41
Python dependencies:
aeon: 1.2.0
pip: 25.2
setuptools: 65.5.0
scikit-learn: 1.6.1
numpy: 2.2.6
numba: 0.61.2
scipy: 1.15.3
pandas: 2.3.1