# Channel positions are not present in DigMontage

**URL:** <https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359>\
**Category:** Support & Discussions\
**Tags:** preprocessing\
**Created:** [August 2, 2022, 9:31am UTC](https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359 "2022-08-02T09:31:04Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![sidgupta234](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/sidgupta234/32/1789_2.png) [@sidgupta234](https://mne.discourse.group/u/sidgupta234)\
**Post date:** [August 2, 2022, 9:31am UTC](https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359/1 "2022-08-02T09:31:04Z")

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- MNE version: 1.0.3
- operating system: macOS 12.4

**📄 Please also provide relevant code snippets – ideally a [minimal working example](https://stackoverflow.com/help/minimal-reproducible-example) (MWE).**

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

```

generates the following warning,

```python
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:

```python
<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?

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<div class="post-metadata">

**Author:** ![cbrnr](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/cbrnr/32/1409_2.png) [@cbrnr](https://mne.discourse.group/u/cbrnr)\
**Post date:** [August 2, 2022, 9:32am UTC](https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359/2 "2022-08-02T09:32:08Z")

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What is your question?

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<div class="post-metadata">

**Author:** ![sidgupta234](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/sidgupta234/32/1789_2.png) [@sidgupta234](https://mne.discourse.group/u/sidgupta234)\
**Post date:** [August 2, 2022, 9:35am UTC](https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359/3 "2022-08-02T09:35:15Z")

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thank you, have added the question.

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<div class="post-metadata">

**Author:** ![cbrnr](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/cbrnr/32/1409_2.png) [@cbrnr](https://mne.discourse.group/u/cbrnr)\
**Post date:** [August 2, 2022, 9:42am UTC](https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359/4 "2022-08-02T09:42:55Z")

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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

```python
montage.plot()

```

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

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<div class="post-metadata">

**Author:** ![sidgupta234](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/sidgupta234/32/1789_2.png) [@sidgupta234](https://mne.discourse.group/u/sidgupta234)\
**Post date:** [August 2, 2022, 10:26am UTC](https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359/5 "2022-08-02T10:26:10Z")

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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](https://static-02.hindawi.com/articles/cin/volume-2016/2758103/figures/2758103.fig.008.svgz)

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<div class="post-metadata">

**Author:** ![cbrnr](https://yyz2.discourse-cdn.com/free1/user_avatar/mne.discourse.group/cbrnr/32/1409_2.png) [@cbrnr](https://mne.discourse.group/u/cbrnr)\
**Post date:** [August 2, 2022, 11:10am UTC](https://mne.discourse.group/t/channel-positions-are-not-present-in-digmontage/5359/6 "2022-08-02T11:10:42Z")

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

[https://mne.tools/dev/generated/mne.channels.make\_dig\_montage.html](https://mne.tools/dev/generated/mne.channels.make_dig_montage.html)

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_*()`.