function [freq] = ft_freqinterpolate(cfg, freq)

% FT_FREQINTERPOLATE interpolates frequencies by looking at neighbouring

% values or simply replaces a piece in the spectrum by NaN.

%

% Use as

% freq = ft_freqinterpolate(cfg, freq)

% where freq is the output of FT_FREQANALYSIS or FT_FREQDESCRIPTIVES and the

% configuration may contain

% cfg.method = 'nan', 'linear' (default = 'nan')

% cfg.foilim = Nx2 matrix with begin and end of each interval to be

% interpolated (default = [49 51; 99 101; 149 151])

%

% To facilitate data-handling and distributed computing you can use

% cfg.inputfile = ...

% cfg.outputfile = ...

% If you specify one of these (or both) the input data will be read from a *.mat

% file on disk and/or the output data will be written to a *.mat file. These mat

% files should contain only a single variable, corresponding with the

% input/output structure.

%

% See also FT_FREQANALYSIS, FT_FREQDESCRIPTIVES, FT_FREQSIMULATION

% Copyright (C) 2009, Aldemar Torres Valderama

%

% 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 debug

ft_preamble loadvar freq

ft_preamble provenance freq

% the ft_abort variable is set to true or false in ft_preamble_init

if ft_abort

return

end

% check if the input data is valid for this function

freq = ft_checkdata(freq, 'datatype', 'freq', 'feedback', 'yes');

% set the defaults

cfg.method = ft_getopt(cfg, 'method', 'nan');

cfg.foilim = ft_getopt(cfg, 'foilim', [49 51; 99 101; 149 151]);

for i = 1:size(cfg.foilim,1)

% determine the exact frequency bins to interpolate

peakbeg = nearest(freq.freq, cfg.foilim(i,1));

peakend = nearest(freq.freq, cfg.foilim(i,2));

% update the configuration

cfg.foilim(i,1) = freq.freq(peakbeg);

cfg.foilim(i,2) = freq.freq(peakend);

if strcmp(cfg.method, 'nan')

switch freq.dimord

case 'chan_freq'

freq.powspctrm(:,peakbeg:peakend) = nan;

case 'chan_freq_time'

freq.powspctrm(:,peakbeg:peakend,:) = nan;

case 'rpt_chan_freq'

freq.powspctrm(:,:,peakbeg:peakend) = nan;

case 'rpt_chan_freq_time'

freq.powspctrm(:,:,peakbeg:peakend,:) = nan;

otherwise

ft_error('unsupported dimord');

end % switch

elseif strcmp(cfg.method, 'linear')

ft_error('not yet implemented');

else

ft_error('unsupported method');

end

end % for each frequency range

% do the general cleanup and bookkeeping at the end of the function

ft_postamble debug

ft_postamble previous freq

ft_postamble provenance freq

ft_postamble history freq

ft_postamble savevar freq