Error during read of Nihon file

[tharikjose]

Describe the bug

I am facing an error during the reading phase of a Nihon EEG file. The problem is during the reading of the .21E file. The EEG is not corrupted since it can be opened in the Nihon program.

Steps to reproduce

import mne

raw = mne.io.read_raw_nihon('Nihon/Nihon_Salvo_em_Tres_Montagens/DA7521RO.EEG')

Expected results

Expected to get the raw data of the EEG file.

Actual results

Loading DA7521RO.EEG
Found 21E file, reading channel names.
Traceback (most recent call last):
File "C:/Users/Sorrino/Documents/Faculdade/EESC/01 - Mestrado/Reading EEG/Reading Nihon.py", line 6, in
raw = mne.io.read_raw_nihon('Nihon/Nihon_Salvo_em_Tres_Montagens/DA7521RO.EEG')
File "C:\Users\Sorrino\anaconda3\envs\mne_dev\lib\site-packages\mne\io\nihon\nihon.py", line 46, in read_raw_nihon
return RawNihon(fname, preload, verbose)
File "", line 24, in init
File "C:\Users\Sorrino\anaconda3\envs\mne_dev\lib\site-packages\mne\io\nihon\nihon.py", line 311, in init
header = _read_nihon_header(fname)
File "C:\Users\Sorrino\anaconda3\envs\mne_dev\lib\site-packages\mne\io\nihon\nihon.py", line 126, in _read_nihon_header
_chan_labels = _read_21e_file(fname)
File "C:\Users\Sorrino\anaconda3\envs\mne_dev\lib\site-packages\mne\io\nihon\nihon.py", line 119, in _read_21e_file
_chan_labels[idx] = name.strip()
IndexError: list assignment index out of range

Process finished with exit code 1

Additional information

Platform: Windows-10-10.0.18362-SP0
Python: 3.8.5 (default, Sep 3 2020, 21:29:08) [MSC v.1916 64 bit (AMD64)]
Executable: C:\Users\Sorrino\anaconda3\envs\mne\python.exe
CPU: Intel64 Family 6 Model 94 Stepping 3, GenuineIntel: 8 cores
Memory: 7.9 GB

mne: 0.21.0
numpy: 1.19.1 {blas=mkl_rt, lapack=mkl_rt}
scipy: 1.5.0
matplotlib: 3.3.1 {backend=Qt5Agg}

sklearn: 0.23.2
numba: 0.51.2
nibabel: 3.1.1
cupy: Not found
pandas: 1.1.3
dipy: 1.2.0
mayavi: 4.7.2
pyvista: 0.26.1 {pyvistaqt=0.2.0, OpenGL 4.5.0 NVIDIA 451.48 via GeForce GTX 960M/PCIe/SSE2}
vtk: 9.0.1
PyQt5: 5.15.1
DA7521RO.zip

[agramfort]

@fraimondo can you have a look?

[fraimondo]

Hello, I checked the attached files.

The problem is not only with the 21E file which has 1096 channels defined (which I fixed easily).

This is a newer EEG system: EEG-1200A V01.00

Can you please provide an EDF file of the same recording exported with the Nihon Kohden software? I wan't to do some tests before pushing the fixes.

[tharikjose]

I have the EDF file of another reading in which the same problem occurs.
DA7521RN.zip

[fraimondo]

Just to be sure. In the ZIP file you sent there is a DA7521NN.edf and a DA7521RN.EEG file. Are you sure it's the right EDF? (I noticed the NN vs RN at the end).

If this is the case, then I don't have good news:

In [13]: raw_edf                                                                                                                        
Out[13]: <RawEDF | DA7521NN.edf, 48 x 3200 (16.0 s), ~1.3 MB, data loaded>

In [14]: raw_nk                                                                                                                         
Out[14]: <RawNihon | DA7521RN.EEG, 1 x 200 (1.0 s), ~11 kB, data loaded>

Even with allowing the reader to process EEG-1200A V01.00 files, the data is not correctly loaded. Without documentation or code that properly reads this kind of files, it will be a bit difficult to make it work.

It is an issue that the error message is not correct. I will create a PR for this.