nt_find_bad_channels

[iBad,toGood]=nt_find_bad_channels(x,proportion,thresh1,thresh2,thresh3) - find bad channels

   iBad: indices of bad channels
   toGood: matrix to good channels

   x: data
   proportion: proportion of time above threshold(s) [default: 0.5]
   thresh1: threshold relative to median absolute value over all data [default: 3]
   thresh2: absolute threshold
   thresh3: applies to projection residual

 Thresholds apply to absolute value.
 'thresh3' applies to the residual of the projection of a channel on
 neighboring channels (as calculated by 'sns'), expressed as a proportion
 of median absolute value of that channel. 

 NoiseTools

0001 function [iBad,toGood]=nt_find_bad_channels(x,proportion,thresh1,thresh2,thresh3)
0002 %[iBad,toGood]=nt_find_bad_channels(x,proportion,thresh1,thresh2,thresh3) - find bad channels
0003 %
0004 %   iBad: indices of bad channels
0005 %   toGood: matrix to good channels
0006 %
0007 %   x: data
0008 %   proportion: proportion of time above threshold(s) [default: 0.5]
0009 %   thresh1: threshold relative to median absolute value over all data [default: 3]
0010 %   thresh2: absolute threshold
0011 %   thresh3: applies to projection residual
0012 %
0013 % Thresholds apply to absolute value.
0014 % 'thresh3' applies to the residual of the projection of a channel on
0015 % neighboring channels (as calculated by 'sns'), expressed as a proportion
0016 % of median absolute value of that channel.
0017 %
0018 % NoiseTools
0019 
0020 
0021 if nargin<2||isempty(proportion); proportion=0.5; end
0022 if nargin<3||isempty(thresh1); thresh1=3; end
0023 if nargin<4; thresh2=[]; end
0024 if nargin<5; thresh3=[]; end
0025 
0026 w=ones(size(x));
0027 
0028 if ~isempty(thresh1)
0029     md=median(abs(x(:)));
0030     w(find(abs(x)>thresh1*md))=0;
0031 end
0032 if ~isempty(thresh2)
0033     w(find(abs(x)>thresh2))=0;
0034 end
0035 if ~isempty(thresh3)
0036     NNEIGHBORS=10;
0037     xx=nt_sns(x,NNEIGHBORS); % remove sensor specific
0038     md=median(abs(xx(:)));
0039     xx=xx-x; % residual
0040     for iChan=1:size(x,2)
0041         w(find(abs(xx(:,iChan))>thresh3*md),iChan)=0;
0042     end
0043 end
0044 iBad=find(mean(1-w)>proportion);
0045 
0046 toGood=eye(size(x,2));
0047 toGood(:,iBad)=[];
0048 
0049 if nargout==0
0050     % plot, don't return values
0051     plot(mean(1-w), '.-'); 
0052     h=line([0 size(x,2)],[proportion proportion]); set(h,'linestyle','--');
0053     xlabel('channel'); ylabel('proportion bad');
0054     xlim([0 size(x,2)+1])
0055     
0056     clear iBad toGood
0057 end
0058 
0059     
0060     
0061