[Mne_analysis] epochs with no data?

[Dillan Cellier]

        External Email - Use Caution        

Hi Denis,

Apologies for the delay in getting back to you. I've tried reproducing this
with a MNE sample dataset, and did not get the same effect. It would appear
then, that there might be something special about the data. Unfortunately
this dataset is not one that I collected. It was acquired from the Child
Mind Institute and as such, the extent of my knowledge about it goes only
so far as the public information provided on it!

I tried this on a different subject's data from the same CMI dataset. I got
the same results where the epoch.plot() is dropping over half of the
epochs, however this time this the drop_log is empty (!?!?!) and at this
point i am thoroughly confused. Here is the code where I am constructing
this Epoch object, so that you may see that there shouldn't be any
automatic rejection taking place:

mne.Epochs(eyes_closed, events=epoch_array, tmin=0, tmax=2,
event_id={'twoSec':7}, picks=scalpData, reject_by_annotation=False)

Any other guesses? Thank you for your help!

Best wishes,
Dillan

On Fri, Jan 4, 2019 at 3:30 PM Denis A. Engemann <
denis-alexander.engemann at inria.fr> wrote:

>         External Email - Use Caution
>
> Hum. That sounds puzzling. Can you reproduce this somehow with the MNE
> sample data? That could help to see if there is something wrong in the code
> or if something is special about your data.
>
> Best,
> Denis
>
> On 4 Jan 2019, at 22:24, Dillan Cellier <cellierdillan at gmail.com> wrote:
>
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>
> Hi Denis,
>
> The events are 2 seconds apart from each other.
>
> Thanks!
>
> Dillan
>
> On Fri, Jan 4, 2019 at 3:18 PM Denis A. Engemann <
> denis-alexander.engemann at inria.fr> wrote:
>
>>         External Email - Use Caution
>>
>> Hi Dillan,
>>
>> What is then the distance in seconds between any two events that you
>> passed to the epochs constructor?
>>
>> Denis
>>
>> On 4 Jan 2019, at 22:12, Dillan Cellier <cellierdillan at gmail.com> wrote:
>>
>>         External Email - Use Caution
>>
>> Hi Denis,
>>
>> I limited the tmin and tmax of the epoch to 0 and 2, respectively, since
>> I don't any kind of stimulus onset in these epochs and don't want them to
>> overlap. This is partly what puzzles me, as I would think this would
>> prevent any inclusion of not-real data. My resting state data can be cut
>> into 93 two-second time windows, and this the number of events I am feeding
>> into the epoch object. It is labeling 41 of these 93 as 'NO_DATA'.
>>
>> Thank you very much!
>>
>> Dillan
>>
>> On Fri, Jan 4, 2019 at 3:05 PM Denis A. Engemann <
>> denis-alexander.engemann at inria.fr> wrote:
>>
>>>         External Email - Use Caution
>>>
>>> Hi Dillan,
>>>
>>> This can happen when the epochs selected include (theoretical) samples
>>> beyond the (actual) data range. You should not have many of those epochs.
>>> Can you roughly tell how many no_data labels you found? I‘d need to refresh
>>> my knowledge of the epochs reading code a bit to see if there may be other
>>> reasons for this. Let‘s see what the others say in the meantime.
>>>
>>> Best,
>>> Denis
>>>
>>> On 4 Jan 2019, at 21:56, Dillan Cellier <cellierdillan at gmail.com> wrote:
>>>
>>>         External Email - Use Caution
>>>
>>> Hello again!
>>>
>>> Thank you for your responses on my last question, they were very
>>> helpful. I am running into another problem now, however. I am epoching
>>> resting state data into arbitrary 2 second windows. I am not automatically
>>> rejecting epochs by annotation nor by a rejection parameter. I see that the
>>> epoch object's drop_log is recording nearly the whole first half of the
>>> epochs as "NO_DATA" epochs, however the raw file contains data for those
>>> time indices. I am unsure what could be going on to result in this loss of
>>> data, however it seems especially problematic due to the amount of epochs
>>> dropped. Thank you in advance, again!
>>>
>>> Best wishes,
>>> Dillan
>>>
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