[FieldTrip] ft_freqanalysis without ft_preprocessing

Alexis alexis.makin at liverpool.ac.uk
Mon Jul 29 17:33:13 CEST 2013


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? 


alexis.makin at liv.ac.uk

Network: www.liv.ac.uk/perception-action/

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