# Data structures for comments? (Events? Annotations?)

**URL:** <https://mne.discourse.group/t/data-structures-for-comments-events-annotations/1460>\
**Category:** Mailing List Archive (read-only)\
**Tags:** list-archive\
**Created:** [March 19, 2018, 11:19pm UTC](https://mne.discourse.group/t/data-structures-for-comments-events-annotations/1460 "2018-03-19T23:19:42Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [March 19, 2018, 11:19pm UTC](https://mne.discourse.group/t/data-structures-for-comments-events-annotations/1460/1 "2018-03-19T23:19:42Z")

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Hello MNE list,

We have prepared an MNE Raw dataset from scratch, and it contains EEG  
and EOG data. We also have manual (written and survey) feedback from  
participants as they recorded the EEG/EOG, and I'm not quite sure if we  
should store this manual feedback as Events, Annotations, a Raw object  
event channel, or something else. We would of course like to be able to  
compare the EEG/EOG against the manual feedback.

Any suggestions are greatly appreciated. I've included some manual  
feedback data samples below, in case that helps.  
Thanks,  
Arlene

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [March 25, 2018, 8:40pm UTC](https://mne.discourse.group/t/data-structures-for-comments-events-annotations/1460/2 "2018-03-25T20:40:07Z")

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hi,

> We have prepared an MNE Raw dataset from scratch, and it contains EEG and  
> EOG data. We also have manual (written and survey) feedback from  
> participants as they recorded the EEG/EOG, and I'm not quite sure if we  
> should store this manual feedback as Events, Annotations,

in MNE, events have no duration. it's an integer to condition mapping  
that maps to a trigger channel.

Annotations were introduced later and each entry consists of 3 infos:  
onset, duration and description.

You have 2 big differences:  
- onset is in seconds in absolution time (no need to change if your  
resample the data)  
- duration is in second  
- description can be any string.

to define epochs you need onsets so no duration is used so it works with events.

HTH  
Alex

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [March 25, 2018, 11:38pm UTC](https://mne.discourse.group/t/data-structures-for-comments-events-annotations/1460/3 "2018-03-25T23:38:17Z")

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Thank you Alexandre, so you would recommend using annotations for this?  
I'm not quite sure what you meant by "to define epochs you need onsets  
so no duration is used so it works with events."

Thanks again  
Arlene

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**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [March 26, 2018, 7:18am UTC](https://mne.discourse.group/t/data-structures-for-comments-events-annotations/1460/4 "2018-03-26T07:18:43Z")

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> Thank you Alexandre, so you would recommend using annotations for this?  
> I'm not quite sure what you meant by "to define epochs you need onsets  
> so no duration is used so it works with events."

epochs have fixed length in mne and are defined from an event onset.  
You will not be presently able to use the Annotations duration to define  
variable length epochs.

Alex