# Basic Question (I think)

**URL:** <https://mne.discourse.group/t/basic-question-i-think/1028>\
**Category:** Mailing List Archive (read-only)\
**Tags:** list-archive\
**Created:** [May 27, 2016, 8:26pm UTC](https://mne.discourse.group/t/basic-question-i-think/1028 "2016-05-27T20:26:25Z")\
**Posts on this page:** 2\
**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:** [May 27, 2016, 8:26pm UTC](https://mne.discourse.group/t/basic-question-i-think/1028/1 "2016-05-27T20:26:25Z")

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Hi,

We have an experiment that we started with EEGLAB and now we are migrating  
to MNE.  
Something like building a classifier to distinguish subjects that are  
"listening" vs "speaking".

At this point, we have one file (.set and .fdt) by condition  
(listening/speaking) that contains several epochs for that condition.

In each epoch, we have only one event that matters for the time serie at  
certain time, always the same (t=1.5 for example).

The thing is, I'm trying to create an Epochs object (maybe an  
`_BaseEpochs`) to visualize / experiment with the data.

So, after using `mne.io.read_epochs_eeglab(set_filename)` I can see that  
the events have no sense to me..

The question is,

Is it reasonable to have 1 event per epoch? or should it be 1 event for the  
hole "Epochs" object?  
And then, whats the way I can combine all this data? (I'm currently using  
`mne.concatenate_epochs([listening_epochs, speaking_epochs])`)

For example, imagine I have 100 epochs for the class listening, and 200  
epochs for the class speaking.

After I concatenate the epochs, should I have this 2 events?

[(1000 0 1), (1000 0 2)]  
(lets say 1000 is the frame corresponding to the event at time 1.5 secs, 1  
is the event id for speaking and 2 for listening)

or should I have 300 events?  
[(1000 0 1)]\*100 + [(1000 0 2)]\*200

I'm new at EEG so maybe I'm missing a simple detail.

Thanks a lot.

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<div class="post-metadata">

**Author:** ![system](https://global.discourse-cdn.com/free1/uploads/mne/original/1X/85cc6bd2b69cb698a166dc6d880fb550510d0144.jpeg) [@system](https://mne.discourse.group/u/system)\
**Post date:** [June 4, 2016, 12:16pm UTC](https://mne.discourse.group/t/basic-question-i-think/1028/2 "2016-06-04T12:16:05Z")

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hi Pablo,

are these questions still relevant after your progress on github?

A