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Fix eeglab loading issue while calling _get_montage_information due to scalar x,y,z in 'nodatchans'#13395

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wmvanvliet merged 11 commits intomne-tools:mainfrom
emrecncelik:main
Sep 2, 2025
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Fix eeglab loading issue while calling _get_montage_information due to scalar x,y,z in 'nodatchans'#13395
wmvanvliet merged 11 commits intomne-tools:mainfrom
emrecncelik:main

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@emrecncelik emrecncelik commented Aug 26, 2025

Reference issue

This issue was raised in the forum: https://mne.discourse.group/t/saved-using-eeglab-the-set-file-cannot-be-opened/11237

It was also raised in #11227 but was marked as closed.

Bug summary

Minimal code that reproduces the error for specific eeglab data, you should download and unzip the data in the following URL: https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/PX8PND

import mne
epochs = mne.io.read_epochs_eeglab("./dataverse_files/AVC1_Full_MARA.set")

Results in (summarized),

File ~/anaconda3/lib/python3.12/site-packages/mne/io/eeglab/eeglab.py:230, in _get_info(eeg, eog, montage_units)
    228 if eeg_has_ch_names_info:
    229     has_pos = _eeg_has_montage_information(eeg)
--> 230     ch_names, ch_types, eeg_montage = _get_montage_information(
    231         eeg, has_pos, montage_units=montage_units
    232     )
    233     update_ch_names = False
    234 else:  # if eeg.chanlocs is empty, we still need default chan names

File ~/anaconda3/lib/python3.12/site-packages/mne/io/eeglab/eeglab.py:173, in _get_montage_information(eeg, get_pos, montage_units)
    170 ys = nodatchans.get("Y", [])
    171 zs = nodatchans.get("Z", [])
--> 173 for type_, description, x, y, z in zip(types, descriptions, xs, ys, zs):
    174     if type_ != "FID":
    175         continue

TypeError: 'float' object is not iterable

What does this implement/fix?

This error was caused by xs, ys, zs being a float value rather than an iterable or array. Added np.atleast_1d function after getting the x, y, z values to ensure they are iterables.

Additional information

  • I do not have access to the data from the previous issue and the forum posts but the problem looks the same.

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welcome bot commented Aug 26, 2025

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@emrecncelik emrecncelik changed the title Fix eeglab loading issue while calling _get_montage_information due to scalar x,y,z in 'nodatchans' Fix eeglab loading issue while calling _get_montage_information due to scalar x,y,z in 'nodatchans' Aug 26, 2025
drammock
drammock approved these changes Aug 26, 2025
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thanks for the clear reproducible example and the fix! I confirm the fix works with the linked files and the code in this PR. Could you please add a changelog entry? doc/changes/dev/13395.bugfix.rst; see other files in that folder for examples. First-time contributors (I think that applies to you?) should use the :newcontrib: role in the changelog entry, and add themselves (alphabetically) to doc/changes/names.inc also.

larsoner
larsoner approved these changes Aug 27, 2025
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Comments addressed, marking for merge-when-green -- thanks in advance @emrecncelik !

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emrecncelik commented Aug 27, 2025

Thank you! I've had a tiny bit of trouble with the change log since I'm not that familiar with it, sorry for the hassle.

@wmvanvliet wmvanvliet merged commit 17c4e03 into mne-tools:main Sep 2, 2025
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welcome bot commented Sep 2, 2025

🎉 Congrats on merging your first pull request! 🥳 Looking forward to seeing more from you in the future! 💪

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@drammock drammock drammock approved these changes

@larsoner larsoner larsoner approved these changes

@agramfort agramfort Awaiting requested review from agramfort agramfort is a code owner

@dengemann dengemann Awaiting requested review from dengemann

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@emrecncelik @drammock @larsoner @wmvanvliet