% fieldtrip2eeglab - convert Fieldtrip structures to EEGLAB dataset

%

% EEG = fieldtrip2eeglab(header, rawdata, evt);

% EEG = fieldtrip2eeglab(data);

%

% Inputs:

% header - Fieldtrip data header

% rawdata - Fieldtrip raw data

% evt - Fieldtrip event structure (optional)

% data - Fieldtrip data out of ft_preprocessing. Note that this uses

% a legacy conversion method. It is better to use

% fieldtrip2eeglab(data.hdr, data.trial) to use the default

% FileIO API.

%

% Output:

% EEG - EEGLAB structure

%

% Author: Arnaud Delorme, UCSD

% Copyright (C) Arnaud Delorme, UCSD 2018

%

% This file is part of EEGLAB, see http://www.eeglab.org

% for the documentation and details.

%

% Redistribution and use in source and binary forms, with or without

% modification, are permitted provided that the following conditions are met:

%

% 1. Redistributions of source code must retain the above copyright notice,

% this list of conditions and the following disclaimer.

%

% 2. Redistributions in binary form must reproduce the above copyright notice,

% this list of conditions and the following disclaimer in the documentation

% and/or other materials provided with the distribution.

%

% THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

% AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

% IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

% ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE

% LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

% CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

% SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

% INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

% CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

% ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF

% THE POSSIBILITY OF SUCH DAMAGE.

function EEG = fieldtrip2eeglab(header,data,evt)

if nargin < 3

evt = [];

end

if nargin >= 2

EEG = pop_fileio(header, data, evt);

else

fprintf(2, 'fieldtrip2eeglab: Use 2-input argument, header and data to use the fileio API to convert Fieldtrip data\n')

if isfield(header, 'hdr')

% use the hdr field in the data

hdr = header.hdr;

else

% create a minimal header

hdr.nChans = numel(header.label);

hdr.nSamplesPre = 0; % FIXME perhaps better to make it nan?; And what about nSamplesPst?

if iscell(header.trial)

hdr.nTrials = numel(header.trial);

hdr.nSamples = numel(header.time{1}); % variable length trials will be caught below

if isfield(header, 'fsample')

hdr.Fs = header.fsample;

else

hdr.Fs = 1./mean(diff(header.time{1}));

end

else

hdr.nTrials = size(header.trial,1);

hdr.nSamples = numel(header.time);

if isfield(header, 'fsample')

hdr.Fs = header.fsample;

else

hdr.Fs = 1./mean(diff(header.time));

end

end

end

EEG = pop_fileio(hdr, header.trial);

if iscell(EEG.data) && length(EEG.data) == 1

EEG.data = EEG.data{1};

EEG.times = header.time{1};

elseif iscell(EEG.data)

len = cellfun(@(x)size(x,2), EEG.data);

if length(unique(len)) > 1

error('Cannot convert epochs of different length');

end

% EEG.data = [ EEG.data{:} ];

EEG.data = cat(3, EEG.data{:});

EEG.pnts = len(1);

EEG.times = header.time{1};

else

% error('Unknown fieldtrip data format');

% the trial field was a 3D matrix

EEG.data = permute(EEG.data, [2 3 1]);

EEG.times = header.time;

% overrule the previously created metadata

[EEG.nbchan, EEG.pnts, EEG.trials] = size(EEG.data);

end

EEG.xmin = EEG.times(1);

EEG.xmax = EEG.times(end);

end