[FieldTrip] ft_freqanalysis without ft_preprocessing

Eelke Spaak eelke.spaak at donders.ru.nl
Mon Jul 29 17:51:38 CEST 2013

Hi Alexis,

How does your data structure look exactly? I.e. what does matlab display
when you type 'data' at the prompt? The error message suggests that it is
not yet quite in the appropriate fieldtrip format.

Op 29 jul. 2013 17:36 schreef "Alexis" <alexis.makin at liverpool.ac.uk> het

> Hi
> I already have data which has been cleaned, filtered and artefact rejected
> etc.
> It is now .mat format (trials X electrodes X time).
> I can follow the advice from the wiki below to make a structure which
> should be compatible with ft_freqanalysis:
> Alternatively, if you already are able to read the data into Matlab, you
> can reformat that data within Matlab into a datastructure that is
> compatible with FieldTrip. Raw data that is comparable with the output of
> preprocessing should consist of a structure with the fields
> data.label   % cell-array containing strings, Nchan X 1
> data.fsample % sampling frequency in Hz, single number
> data.trial   % cell-array containing a data matrix for each trial (1 X Ntrial), each data matrix is    Nchan X Nsamples
> data.time    % cell-array containing a time axis for each trial (1 X Ntrial), each time axis is a 1 X Nsamples vector
> data.trialinfo % this field is optional, but can be used to store trial-specific information, such as condition numbers, reaction times, correct responses etc. The dimensionality is N x M
> but when I try to run ft_freqanalysis(cfg, data) on this
> I get the following error messages:
> ??? Error using ==> ft_checkdata at 366
> This function requires raw, comp or mvar data as input.
> Error in ==> ft_freqanalysis at 219
> data = ft_checkdata(data, 'datatype', {'raw', 'comp',
> 'mvar'}, 'feedback', cfg.feedback, 'hassampleinfo', 'yes');
> How to I tell the ft_checkdata function what datatype I have? Is this a
> simple problem?
> Is it common to use fieldtrip functions on data which has already been
> preprocessed in another way? Or is this not advisable?
> cheers,
> Alexis
> alexis.makin at liv.ac.uk
> Network: www.liv.ac.uk/perception-action/
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> fieldtrip at donders.ru.nl
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