[Mne_analysis] Applying ICA with No Components Selected out but Signal Changes Using Default Parameters

Alexandre Gramfort alexandre.gramfort at inria.fr
Wed Jul 3 02:30:58 EDT 2019
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hi,

can you check that the number of components you fit is equal to the number
of channels?
If it's less you have a dimensionality reduction step.

Alex


On Tue, Jul 2, 2019 at 11:28 PM Mainak Jas <mainakjas at gmail.com> wrote:

>         External Email - Use Caution
>
> Hi Alex,
>
> Could you provide us a full script on the MNE sample data that we can run?
>
> Mainak
>
> On Tue, Jul 2, 2019 at 5:14 PM Rockhill, Alexander P. <
> AROCKHILL at mgh.harvard.edu> wrote:
>
>> Also, of note the ica scale is off by quite a lot in the plot_sources
>> plot, it is way too zoomed in.
>>
>> Alex
>>
>> Translational NeuroEngineering Laboratory
>> Division of Neurotherapeutics, Department of Psychiatry
>> Massachusetts General Hospital, Martinos Center
>> 149 13th St Charlestown #2301, Boston, MA 02129
>> ------------------------------
>> *From:* mne_analysis-bounces at nmr.mgh.harvard.edu <
>> mne_analysis-bounces at nmr.mgh.harvard.edu> on behalf of Rockhill,
>> Alexander P. <AROCKHILL at mgh.harvard.edu>
>> *Sent:* Tuesday, July 2, 2019 3:25 PM
>> *To:* mne_analysis at nmr.mgh.harvard.edu
>> *Subject:* [Mne_analysis] Applying ICA with No Components Selected out
>> but Signal Changes Using Default Parameters
>>
>> Hi,
>>
>>     In an analysis, I am running:
>>
>> ica = ICA(method='fastica', n_components=n_components,  #
>> n_components=None
>>           random_state=seed)
>> ica.fit(inst2)
>> ...
>> inst2 = ica.apply(inst2, exclude=ica.exclude)
>>
>>     and when I skip all intermediate steps and just fit the ICA and apply
>> it with an empty list for ica.exclude the signal still changes, quite a
>> bit. I thought if no components were selected out and all the max PCA
>> components were used the signal would be unchanged or basically unchanged.
>> Is this a bug or something with my implementation?
>>
>> Thanks,
>>
>> Alex
>>
>> Translational NeuroEngineering Laboratory
>> Division of Neurotherapeutics, Department of Psychiatry
>> Massachusetts General Hospital, Martinos Center
>> 149 13th St Charlestown #2301, Boston, MA 02129
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