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<div class="moz-cite-prefix">Hi Nenad,<br>
<br>
what Casper said is not quite true. You can pad segmented trials,
but you are limited in how to pad. There are different ways of
padding, and what Casper was referring to is true data padding.
Once you segmented your trials you cannot get back to your
recorded data and attach more data to it. This is because
filtering artifacts at edges etc would result in discontinuities
and the like. However, there are other ways to achieve what you
want. The most elegant way in my opinion is what Casper already
suggested. Just for completeness, you can still pad using
zero-padding (i.e. adding a bunch of 0s in the beginning and at
the end of your trials). Other ways are mean-padding (pad with the
mean value), or edge-padding (using the first/last value to
padding). However, with all these methods you mostly also add a
discontinuity, but you explicitly ask for that in this case :) The
most elegant solution here might be to use mirror-padding, which
is recently implemented. <br>
See here:<br>
<a class="moz-txt-link-freetext" href="http://fieldtrip.fcdonders.nl/reference/ft_preprocessing">http://fieldtrip.fcdonders.nl/reference/ft_preprocessing</a><br>
and here:<br>
<a class="moz-txt-link-freetext" href="http://fieldtrip.fcdonders.nl/reference/ft_preproc_padding">http://fieldtrip.fcdonders.nl/reference/ft_preproc_padding</a><br>
<br>
Best,<br>
Jörn<br>
<br>
On 6/22/2013 2:32 PM, Casper van Heck wrote:<br>
</div>
<blockquote
cite="mid:CAJ7RtREwKrgNVCko=XkrjofHJduL64iEU0mESovdcrXqsm7M0A@mail.gmail.com"
type="cite">
<div dir="ltr">Dear Nenad,
<div><br>
</div>
<div>I think the option cfg.padding only works for that
iteration of ft_preprocessing, but what you can do, is select
larger segments initially, and then run ft_preprocessing again
with smaller segments. </div>
<div><br>
</div>
<div>While you can set ft_preprocessing to apply multiple
different filters in one go (like a low-pass, a high-pass, and
a DFT-filter, for example), using a similar filter multiple
times (like a high-pass filter at 4Hz, and another at 8Hz) is
usually not required, or recommended. If you do multiple
analyses on the same data (which, for example, require
different filters) you could find it useful to create multiple
smaller pipelines with their own ft_preprocessing. Debugging
complex analyses can be a lot easier that way:)</div>
<div><br>
</div>
<div>Hope this helps,</div>
<div><br>
</div>
<div>Casper</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Sat, Jun 22, 2013 at 1:34 PM, Nenad
Polomac <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:polomacnenad@gmail.com" target="_blank">polomacnenad@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">Dear all,
<div><br>
</div>
<div>In my pipeline I need two times to filter data with
ft_preprocessing. Is it somehow possible to pad trials
after segmentation? I need this in order to avoid filter
artifacts during the second filtering.</div>
<div><br>
</div>
<div>Thank you in advance!</div>
<span class="HOEnZb"><font color="#888888">
<div><br>
</div>
<div>Nenad</div>
</font></span><br>
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</blockquote>
</div>
<br>
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<br>
<pre class="moz-signature" cols="72">--
Jörn M. Horschig
PhD Student
Donders Institute for Brain, Cognition and Behaviour
Centre for Cognitive Neuroimaging
Radboud University Nijmegen
Neuronal Oscillations Group
FieldTrip Development Team
P.O. Box 9101
NL-6500 HB Nijmegen
The Netherlands
Contact:
E-Mail: <a class="moz-txt-link-abbreviated" href="mailto:jm.horschig@donders.ru.nl">jm.horschig@donders.ru.nl</a>
Tel: +31-(0)24-36-68493
Web: <a class="moz-txt-link-freetext" href="http://www.ru.nl/donders">http://www.ru.nl/donders</a>
Visiting address:
Trigon, room 2.30
Kapittelweg 29
NL-6525 EN Nijmegen
The Netherlands</pre>
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