% -------------------------------------------------------------------------------------------------
% BeatGrouping.m: Attempt to cluster ECG beats and average beat estimation.
% Rough version to be tested, tuned and refined.
%
% Copyright (C) 2004 Maurizio Varanini, Clinical Physiology Institute, CNR, Pisa, Italy
%
% This program 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 2 of the License, or (at your option) any later version.
%
% This program is distributed "as is" and "as available" in the hope that it will be useful,
% but WITHOUT ANY WARRANTY of any kind; 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 this program;
% if not, write to the Free Software Foundation, Inc.,
% 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
%
% For any comment or bug report, please send e-mail to: maurizio.varanini@ifc.cnr.it
% -------------------------------------------------------------------------------------------------
function beatGroup= beatGrouping(x1, x2, viq, npt)
vvqp=1:length(viq);
thrp=1;
thr=1.1;
tha=0.2;
ic=0;
while(~isempty(vvqp));
ic=ic+1;
viqcp=viq(vvqp);
nvq=length(vvqp);
% build a rough centroid of selected beats
[avgP1Q, avgP2Q]= roughAvgClass(x1, x2, viqcp, npt);
% evaluate the distance from the mean template
[mid da]=dist2cAvg(x1, x2, avgP1Q, avgP2Q, viqcp);
dam=meansc(mid,25,25); % mean distance
if(ic==1) tha=0.2*dam; end
vqp=find(mid < tha +thrp*dam); % array of index of similar beats
viqp=viqcp(vqp);
% build the centroid of selected beats
[avgC1Q(:,ic), avgC2Q(:,ic)]= avgClass(x1, x2, viqp, npt);
% evaluate the distance from the centroid
% [mid, mij, da]=dist2cAvgW(x1, x2, avgC1Q(:,ic), avgC2Q(:,ic), viqcp);
[mid, mij, da, mih]=dist2cAvgWh(x1, x2, avgC1Q(:,ic), avgC2Q(:,ic), viqcp);
dam=meansc(mid,25,25); % mean distance
iq=find(mid < tha+thr*dam); % array of index of similar beats
vq{ic}=vvqp(iq);
vij(vq{ic})=mij(iq);
vih(vq{ic})=mih(iq);
vqcc(vq{ic})=ic;
vvqp=vvqp(find(mid >= tha+thr*dam));
end
beatGroup.vq=vq;
beatGroup.vij=vij;
beatGroup.vih=vih;
beatGroup.vqcc=vqcc;
beatGroup.avgC1Q=avgC1Q;
beatGroup.avgC2Q=avgC2Q;
% end function
%------------------------------------------------------------
% evaluate the distance from the mean template
function [mid, da]= dist2cAvg(x1, x2, avg1Q, avg2Q, iw )
npt=length(avg1Q);
nq=length(iw);
for iq=1:nq
mid(iq)=999999999999;
j=iw(iq);
d1= x1(j:j+npt-1)-avg1Q;
d2= x2(j:j+npt-1)-avg2Q;
da=sum(abs(d1)+abs(d2));
if(da<mid(iq)) mid(iq)=da; end
end
% end function
%------------------------------------------------------------
% evaluate the distance from the mean template
function [mid, mij, da]=dist2cAvgW(x1, x2, avg1Q, avg2Q, iw )
npt=length(avg1Q);
nq=length(iw);
for iq=1:nq
mid(iq)=999999999999;
ij=iw(iq)-20;
fj=ij+20;
for j=ij:fj
d1= x1(j:j+npt-1)-avg1Q;
d2= x2(j:j+npt-1)-avg2Q;
da=sum(abs(d1)+abs(d2));
if(da<mid(iq)) mid(iq)=da; mij(iq)=j; end
end
end
% end function
%------------------------------------------------------------
% evaluate the distance from the mean template
function [mid, mij, da, mih]=dist2cAvgWh(x1, x2, avg1Q, avg2Q, iw )
npt=length(avg1Q);
nq=length(iw);
mind = min(abs(avg1Q)+abs(avg2Q));
maxd = max(abs(avg1Q)+abs(avg2Q));
for iq=1:nq
mid(iq)=999999999999;
ij=iw(iq)-20;
fj=ij+20;
for j=ij:fj
for h=linspace((-maxd+mind)/10,(maxd-mind)/10,20)
d1= x1(j:j+npt-1)-avg1Q+h;
d2= x2(j:j+npt-1)-avg2Q+h;
da=sum(abs(d1)+abs(d2));
if(da<mid(iq)) mid(iq)=da; mij(iq)=j; mih(iq)=h; end
end
end
end
% end function
%------------------------------------------------------------
% build the centroid of selected beats
function [avg1Q, avg2Q]= avgClass(x1, x2, viq, npt)
nnq=length(viq);
avg1Q=0;
avg2Q=0;
for jq=1:nnq
ij=viq(jq);
fj=ij+npt-1;
avg1Q= avg1Q+x1(ij:fj);
avg2Q= avg2Q+x2(ij:fj);
end
avg1Q=avg1Q/nnq;
avg2Q=avg2Q/nnq;
% end function
%------------------------------------------------------------
% Build a rough centroid of selected beats
function [avg1Q, avg2Q]= roughAvgClass(x1, x2, viq, npt)
% built matrix of QRS templates
nq=length(viq);
for iq=1:nq
ji=viq(iq); jf=ji+npt-1;
x1M(:,iq)= x1(ji:jf);
x2M(:,iq)= x2(ji:jf);
end
for is=1:npt
avg1Q(is,1)=meansc(x1M(is,:),10,10);
avg2Q(is,1)=meansc(x2M(is,:),10,10);
end
% end function