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function [cfg, artifact] = ft_artifact_eog(cfg, data)
% FT_ARTIFACT_EOG scans data segments of interest for EOG artifacts.
%
% Use as
% [cfg, artifact] = ft_artifact_eog(cfg)
% with the configuration options
% cfg.dataset = string with the filename
% or
% cfg.headerfile = string with the filename
% cfg.datafile = string with the filename
% and optionally
% cfg.headerformat
% cfg.dataformat
%
% Alternatively you can use it as
% [cfg, artifact] = ft_artifact_eog(cfg, data)
% where the input data is a structure as obtained from FT_PREPROCESSING.
%
% In both cases the configuration should also contain
% cfg.trl = structure that defines the data segments of interest, see FT_DEFINETRIAL
% cfg.continuous = 'yes' or 'no' whether the file contains continuous data
%
% Prior to artifact detection, the data is preprocessed (again) with the following
% configuration parameters, which are optimal for identifying EOG artifacts.
% cfg.artfctdef.eog.bpfilter = 'yes'
% cfg.artfctdef.eog.bpfilttype = 'but'
% cfg.artfctdef.eog.bpfreq = [1 15]
% cfg.artfctdef.eog.bpfiltord = 4
% cfg.artfctdef.eog.hilbert = 'yes'
%
% Artifacts are identified by means of thresholding the z-transformed value
% of the preprocessed data.
% cfg.artfctdef.eog.channel = Nx1 cell-array with selection of channels, see FT_CHANNELSELECTION for details
% cfg.artfctdef.eog.cutoff = z-value at which to threshold (default = 4)
% cfg.artfctdef.eog.trlpadding = number in seconds (default = 0.5)
% cfg.artfctdef.eog.fltpadding = number in seconds (default = 0.1)
% cfg.artfctdef.eog.artpadding = number in seconds (default = 0.1)
%
% The output argument "artifact" is a Nx2 matrix comparable to the "trl" matrix of
% FT_DEFINETRIAL. The first column of which specifying the beginsamples of an
% artifact period, the second column contains the endsamples of the artifactperiods.
%
% To facilitate data-handling and distributed computing, you can use
% cfg.inputfile = ...
% to read the input data from a *.mat file on disk. This mat files should contain
% only a single variable named 'data', corresponding to the input structure.
%
% See also FT_REJECTARTIFACT, FT_ARTIFACT_CLIP, FT_ARTIFACT_ECG, FT_ARTIFACT_EOG,
% FT_ARTIFACT_JUMP, FT_ARTIFACT_MUSCLE, FT_ARTIFACT_THRESHOLD, FT_ARTIFACT_ZVALUE
% Copyright (C) 2003-2011, Jan-Mathijs Schoffelen & Robert Oostenveld
%
% This file is part of FieldTrip, see http://www.fieldtriptoolbox.org
% for the documentation and details.
%
% FieldTrip is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% FieldTrip is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with FieldTrip. If not, see <http://www.gnu.org/licenses/>.
%
% $Id$
% these are used by the ft_preamble/ft_postamble function and scripts
ft_revision = '$Id$';
ft_nargin = nargin;
ft_nargout = nargout;
% do the general setup of the function
ft_defaults
ft_preamble init
% ft_preamble provenance is not needed because just a call to ft_artifact_zvalue
% ft_preamble loadvar data is not needed because ft_artifact_zvalue will do this
% the ft_abort variable is set to true or false in ft_preamble_init
if ft_abort
return
end
% check if the input cfg is valid for this function
cfg = ft_checkconfig(cfg, 'renamed', {'datatype', 'continuous'});
cfg = ft_checkconfig(cfg, 'renamedval', {'continuous', 'continuous', 'yes'});
cfg = ft_checkconfig(cfg, 'forbidden', {'padding', 'pretim', 'psttim'});
% set default rejection parameters
cfg.artfctdef = ft_getopt(cfg, 'artfctdef', []);
cfg.artfctdef.eog = ft_getopt(cfg.artfctdef, 'eog', []);
cfg.artfctdef.eog.method = ft_getopt(cfg.artfctdef.eog, 'method', 'zvalue');
if isfield(cfg.artfctdef.eog, 'artifact')
fprintf('eog artifact detection has already been done, retaining artifacts\n');
artifact = cfg.artfctdef.eog.artifact;
return
end
if ~strcmp(cfg.artfctdef.eog.method, 'zvalue')
ft_error('EOG artifact detection only works with method=''zvalue''');
end
% for backward compatibility
cfg.artfctdef.eog = ft_checkconfig(cfg.artfctdef.eog, 'renamed', {'sgn', 'channel'});
cfg.artfctdef.eog = ft_checkconfig(cfg.artfctdef.eog, 'renamed', {'passbnd', 'bpfreq'});
cfg.artfctdef.eog = ft_checkconfig(cfg.artfctdef.eog, 'renamed', {'padding', 'trlpadding'});
% settings for preprocessing
cfg.artfctdef.eog.bpfilter = ft_getopt(cfg.artfctdef.eog, 'bpfilter', 'yes');
cfg.artfctdef.eog.bpfreq = ft_getopt(cfg.artfctdef.eog, 'bpfreq', [1 15]);
cfg.artfctdef.eog.bpfiltord = ft_getopt(cfg.artfctdef.eog, 'bpfiltord', 4);
cfg.artfctdef.eog.bpfilttype = ft_getopt(cfg.artfctdef.eog, 'bpfilttype', 'but');
cfg.artfctdef.eog.hilbert = ft_getopt(cfg.artfctdef.eog, 'hilbert', 'yes');
% settings for the zvalue subfunction
cfg.artfctdef.eog.channel = ft_getopt(cfg.artfctdef.eog, 'channel', 'EOG');
cfg.artfctdef.eog.cutoff = ft_getopt(cfg.artfctdef.eog, 'cutoff', 4);
cfg.artfctdef.eog.trlpadding = ft_getopt(cfg.artfctdef.eog, 'trlpadding', 0.5);
cfg.artfctdef.eog.fltpadding = ft_getopt(cfg.artfctdef.eog, 'fltpadding', 0.1);
cfg.artfctdef.eog.artpadding = ft_getopt(cfg.artfctdef.eog, 'artpadding', 0.1);
% construct a temporary configuration that can be passed onto FT_ARTIFACT_ZVALUE
tmpcfg = cfg;
tmpcfg.artfctdef.zvalue = cfg.artfctdef.eog;
tmpcfg.artfctdef = rmfield(tmpcfg.artfctdef, 'eog');
% call the zvalue artifact detection function, where the data is either passed
% into the function by the user or read from file with cfg.inputfile
hasdata = exist('data', 'var');
if ~hasdata
tmpcfg = ft_checkconfig(tmpcfg, 'dataset2files', 'yes');
tmpcfg = ft_checkconfig(tmpcfg, 'required', {'headerfile', 'datafile'});
[tmpcfg, artifact] = ft_artifact_zvalue(tmpcfg);
else
tmpcfg.artfctdef.zvalue.trlpadding = 0;
tmpcfg.artfctdef.zvalue.fltpadding = 0;
ft_warning('trlpadding and fltpadding are set to zero to avoid filter problems with NaN, see bug3193 for details');
[tmpcfg, artifact] = ft_artifact_zvalue(tmpcfg, data);
end
cfg.artfctdef.eog = tmpcfg.artfctdef.zvalue;