Channel positions are not present in DigMontage

  • MNE version: 1.0.3
  • operating system: macOS 12.4

:page_facing_up: Please also provide relevant code snippets – ideally a minimal working example (MWE).

montage = mne.channels.make_standard_montage('standard_1020')
eeg_data_250kz.set_montage(montage, match_case=False, on_missing='warn')

generates the following warning,

RuntimeWarning: DigMontage is only a subset of info. There are 4 channel positions not present in the DigMontage. The required channels are:

['LM', 'LO1', 'LO2', 'IO2'].

Consider using inst.set_channel_types if these are not EEG channels, or use the on_missing parameter if the channel positions are allowed to be unknown in your analyses.

Details of my EEG dataset:

<Info | 7 non-empty values
 bads: []
 ch_names: LM, Fp1, Fp2, AFz, F3, Fz, F4, FC5, FC1, FC2, FC6, C3, Cz, C4, ...
 chs: 31 EEG
 custom_ref_applied: False
 highpass: 0.0 Hz
 lowpass: 100.0 Hz
 meas_date: 2022-06-13 09:12:06 UTC
 nchan: 31
 projs: []
 sfreq: 250.0 Hz

How may I resolve this warning, what are the values for ocular region electrodes in 10-20 system for these 4 electrodes?

What is your question?

thank you, have added the question.

I don’t know where these four electrodes are located, but you need to find the closest matches in the 10–20 (or 10–05) system. You can plot all available location with


If 'standard_1020' is not sufficient, try 'standard_1005'.

1 Like

I find it weird that ocular level electrodes are not getting considered in any of the montage systems. Am I missing a possible montage that may work? Even 10-05 does not have ocular level electrodes listed.

Location of the electrodes: LM is M1 (which can be renamed easily), IO2 is infrared ocular (region between and slightly below two eyes). LO1, LO2 can be viewed here

If you don’t find existing montages with suitable locations, you will need to create your own:

If you happen to have a file with 3D locations, you can read it with one of the various reader functions mne.channels.read_dig_*().