[FieldTrip] Fast Fourier Transform Using EEGLab
Jörn M. Horschig
jorn at artinis.com
Thu Oct 29 16:49:57 CET 2015
Dear Peyton,
You might want to check this out:
http://www.fieldtriptoolbox.org/walkthrough#input_output_structure_of_ft_freqstatistics
And the tutorials on statistic, e.g.
http://www.fieldtriptoolbox.org/tutorial/cluster_permutation_freq
However, note that doing an FFT has nothing to do with ft_freqstatistics. You need ft_freqanalysis for that and did that just fine with the code you shared (and, as with everything in life, there is not *the* correct way to do anything, but the way you did it should be fine).
Best,
Jörn
--
Jörn M. Horschig, PhD, Software Engineer
<http://www.artinis.com/> Artinis Medical Systems | +31 481 350 980
From: fieldtrip-bounces at science.ru.nl [mailto:fieldtrip-bounces at science.ru.nl] On Behalf Of Peyton Finley
Sent: Thursday, October 29, 2015 16:20
To: fieldtrip at science.ru.nl
Subject: [FieldTrip] Fast Fourier Transform Using EEGLab
Hello,
My name is Peyton Finley and I am an undergraduate research student at Wheaton College in Wheaton, Illinois. I am emailing you regarding how to conduct a Fast Fourier Transform using FieldTrip.
Specifically, I am trying to use the function ft_freqstatistics.m to gather statistics for the FFT. The function requires what is noted as a "design matrix". This is the description:
Nxnumobservations: design matrix (for examples/advice, please see the Fieldtrip wiki,
especially cluster-permutation tutorial and the 'walkthrough' design-matrix section)
I checked the FieldTrip wiki site, but I was unable to find anything on this design matrix. What is the design matrix and how do I construct it?
Also, is this the correct way of performing a FFT on EEG data? Is there an alternate method? Before arriving at this point, I have performed the following steps.
cfg = [];
ft_defaults;
cfg.dataset = dataset;
preprocdata=ft_preprocessing(cfg);
data=struct2single(preprocdata);
%% Define cfg for ft_frequanalysis.m and run.
cfg = [];
cfg.output='fourier';
cfg.method='mtmfft';
cfg.outputfile=outputFileName;
cfg.foilim=[0 55];
cfg.tapsmofrq='2';
[freq]=ft_freqanalysis(cfg,data);
%% Define cfg for ft_freqstatistics.m and run.
cfg = [];
cfg.method='analytic';
[stat]=ft_freqstatistics(cfg, freq);
Sincerely,
Peyton Finley
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