<div dir="ltr">Hi Emilie,<div> You can read each channel and then down sample. In the end , you append all the channel. For more information and how to , you can refer to the FAQ: <a href="http://fieldtrip.fcdonders.nl/faq/how_can_i_preprocess_a_dataset_that_is_too_large_to_fit_into_memory">http://fieldtrip.fcdonders.nl/faq/how_can_i_preprocess_a_dataset_that_is_too_large_to_fit_into_memory</a>.</div><div> </div><div> Hope this helps,</div><div> Haiteng<br><div class="gmail_extra"><br><div class="gmail_quote">On 13 December 2014 at 12:00, <span dir="ltr"><<a href="mailto:fieldtrip-request@science.ru.nl" target="_blank">fieldtrip-request@science.ru.nl</a>></span> wrote:<blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left-width:1px;border-left-color:rgb(204,204,204);border-left-style:solid;padding-left:1ex">Send fieldtrip mailing list submissions to<br>
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Today's Topics:<br>
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1. Correction baseline : removing the mean value or high-pass<br>
filtering ? (Kristensen Emmanuelle)<br>
2. Question about how to reduce the file size (Caspar, Emilie)<br>
<br>
<br>
----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Fri, 12 Dec 2014 15:49:10 +0100<br>
From: Kristensen Emmanuelle<br>
<<a href="mailto:emmanuelle.kristensen@gipsa-lab.grenoble-inp.fr">emmanuelle.kristensen@gipsa-lab.grenoble-inp.fr</a>><br>
To: FieldTrip discussion list <<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>><br>
Subject: [FieldTrip] Correction baseline : removing the mean value or<br>
high-pass filtering ?<br>
Message-ID: <<a href="mailto:548B0066.3090309@gipsa-lab.grenoble-inp.fr">548B0066.3090309@gipsa-lab.grenoble-inp.fr</a>><br>
Content-Type: text/plain; charset="utf-8"; Format="flowed"<br>
<br>
Hi,<br>
I would need your opinion, please.<br>
Generally, the baseline correction means to remove a mean value from<br>
each epoch. I am wondering if a high pass filter, applied on the whole<br>
recorded signal, can perform the baseline correction.<br>
What do you think?<br>
Regards<br>
Emmanuelle<br>
<br>
--<br>
Emmanuelle KRISTENSEN<br>
Doctorante au Gipsa-Lab<br>
Equipe VIBS<br>
<br>
<br>
<br>
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Message: 2<br>
Date: Fri, 12 Dec 2014 22:24:17 +0000<br>
From: "Caspar, Emilie" <<a href="mailto:e.caspar@ucl.ac.uk">e.caspar@ucl.ac.uk</a>><br>
To: "<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>" <<a href="mailto:fieldtrip@science.ru.nl">fieldtrip@science.ru.nl</a>><br>
Subject: [FieldTrip] Question about how to reduce the file size<br>
Message-ID: <<a href="mailto:484FAA32-F84A-4BD2-8928-C07265183751@live.ucl.ac.uk">484FAA32-F84A-4BD2-8928-C07265183751@live.ucl.ac.uk</a>><br>
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Dear Fieltrippers,<br>
I did a pilot study on one participant today. Now that I'm trying to analyze my data, I realize that the size file is too big for my computer (size = 3Gb). Even after one hour, the filters (high pass + low pass) were not yet achieved.<br>
<br>
So I would like to see how to reduce the size of my sample BEFORE the filters.<br>
<br>
I know that there is "ft_resampledata", and I did it to reduce the actual sample rate (= 2048) to 256. However, even with this procedure my computer is crashing (even with 16 Go RAM). In addition, I'm not sure that I can resample before filtering (I read different informations).<br>
<br>
Another way I was thinking about was to pre-select electrodes that I need (only 6 electrodes on 64). But here I have two questions:<br>
- Can I pre-process only some electrodes? Does it really reduce size for next preprocesses?<br>
- Is this the correct way to ask? As it crashes, not sure it works.<br>
<br>
cfg = [];<br>
cfg.dataset = [ <a href="http://file.name" target="_blank">file.name</a>];<br>
cfg.channel = 'B5', 'B6', 'B15', 'B16';<br>
allData_prepross = ft_preprocessing(cfg);<br>
cfg.resamplefs = 256;<br>
DataSample = ft_resampledata(cfg, allData_prepross)<br>
<br>
<br>
I would appreciate pieces of advice!<br>
<br>
Many thanks :)<br>
<br>
Emilie<br>
<br>
<br>
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End of fieldtrip Digest, Vol 49, Issue 12<br>
*****************************************<br>
</blockquote></div><br clear="all"><div><br></div>-- <br><div class="gmail_signature"><div dir="ltr"><div><div>Haiteng Jiang </div><div>PhD candidate</div><div>Donders Institute for Brain, Cognition and Behaviour</div><div>Neuronal Oscillations Group </div><div>Computational Cognitive Neuroscience Lab</div></div><div><font face="arial, helvetica, sans-serif"><a href="https://sites.google.com/site/haitengjiang/" target="_blank">https://sites.google.com/site/haitengjiang/</a></font></div></div></div>
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