[FieldTrip] how to use ft_stratify?

[Stolk, A.]

Hi Vitoria,

There is a wikipage that may help you get started, and answer your questions:
http://fieldtrip.fcdonders.nl/example/stratify

Best wishes,
Arjen  

----- Oorspronkelijk bericht -----
> Van: "Vitória Magalhães Piai" <vitoria.piai at gmail.com>
> Aan: fieldtrip at donders.ru.nl
> Verzonden: Zondag 2 juni 2013 11:17:25
> Onderwerp: [FieldTrip] how to use ft_stratify?
> Hi all,
> 
> I'm trying to use ft_stratify for the first time, but (it could be
> just
> me) I don't find the help info helpful enough :)
> What I want to achieve in the end is TFRs of two conditions for which
> the histogram of the reaction time over trials for each condition is
> matched.
> 
> If I understood ft_stratify correctly (and I doubt that), I could use
> this function to select the trials for each condition such that the
> histograms of the RTs match. Then knowing which trials to keep, I run
> ft_freqanalysis on those specifically.
> So question number 1, is that how I should proceed? 'Cause as far as I
> can tell, ft_stratify will not take a whole raw data structure: The
> help
> says "each input is a Nchan X Nobs matrix". So I have to go for the
> RTs
> then.
> 
> Assuming my approach is correct (ft_stratify on RTs of two conditions,
> then move on with only those trials), I've made a matrix Nchan x
> N_trials for each condition.
> % input1 = 265 sensors x 95 RT_trials;
> % input2 = 265 sensors x 100 RT_trials;
> 
> cfgst = [];
> cfgst.method = 'histogram';
> cfgst.equalbinavg = 'no';
> cfgst.numbin = 4;
> cfgst.numiter = 2000; % default
> [output,bin] = ft_stratify(cfgst, input1, input2);
> 
> I then get an error in line 127:
> linearhisto = zeros(ncond, cfg.numbin.^nchan);
> ??? Error using ==> zeros
> Maximum variable size allowed by the program is exceeded.
> 
> Apparently, zeros(2, 4^265) is something matlab doesn't want to
> calculate!
> Am I doing something wrong here? Has anyone worked with this function
> before (with such a number of sensors)?
> 
> Any help is greatly appreciated!
> Cheers, Vitória
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