Why do I get "Array indices must be positive integers or logical values" error when trying to calculate the average range for the last five observation in line 121?

load('ecgClear_1.mat')
x = ecgClear_1(:,1);
Fs = 257;
HF = butter2filtfilt( x, Fs, 20, 'high');
LF = butter2filtfilt( x, Fs, 0.15, 'low');
ecg = x-HF-LF;
figure();
plot(ecg);
%%
% figure()
% plot(x);
ecg_dif = [];
ecg_dif(1:4,1) = 0;
ecg_dif2 = [];
ecg_dif2(1:4,1) = 0;
for n =5:numel(ecg)
    ecg_dif(n,1)= abs(ecg(n,1)-ecg(n-2,1));
    ecg_dif2(n,1)= abs(ecg(n,1)-2*ecg(n-2,1)+ecg(n-4,1));
end
res = 1.3*ecg_dif+1.1*ecg_dif2;
%%
figure()
a1 = subplot(2,1,1);
plot(ecg);
a2 = subplot(2,1,2);
plot(res);
grid on;
a2.XLim = a1.XLim;
%%
A = 100;
id = res>=A;
fl = false(numel(id),1);
for i = 1:numel(id)-6
    s = sum(id(i:i+6));
    if s >= 4
        fl(i) = true;
    end
end
 %%
 T_Lim = fix(0.2*Fs);
 i = 1;
 Q_start = [];
 while i<=numel(id)
    if fl(i)
       Q_start =[Q_start;i];
       i=i+T_Lim;
    else
     i = i+1;
    end
 end
 %%
 T_Lim = fix(0.2*Fs);
 i = 1;
 Q_start = [];
 R_end = [];
 R_peak = [];
 R_fl = false;
 while i<=numel(id)
 if fl(i)
     Q_start =[Q_start;i];
     [~,mID] = max(abs(ecg(i:i+fix(T_Lim*0.5))));
     R_peak = [R_peak; mID+i-1];
     R_fl = true;
     i=i+T_Lim;
     isPlus = ecg(mID+i-1)>0;
     for j = mID+i:i+T_Lim
         if isPlus && R_fl
             if ecg(j)<0
                 R_end = [R_end ; j];
                 R_fl = false;
             end
               
         elseif ~isPlus && R_fl
            if ecg(j)>0
               R_end = [R_end;j];
                R_fl = false;
            end
         end
     end
     if R_fl == true
         R_end = [R_end; mID+i-1+mID];
     end
     i = i+T_Lim;
 else
     i =i+1;
     
  end
 end
     %%
     figure()
     plot(ecg);
     hold on;
     stem(Q_start,ecg(Q_start));
     stem(R_peak,ecg(R_peak));
     stem(R_end,ecg(R_end));
     grid on

%%
QS = [Q_start  R_end];
Data = ecg;
N = size(QS,1);
for i=2:N
    RR(i,1) = (R_peak(i)-R_peak(i-1))/Fs;
end
 RR(1,1)= 0;
QSparams = struct();
 N = size(QS,1);
 for i =1:N
    Q = QS(i,1);
    S = QS(i,2);
     QSparams.M(i,1) = mean(ecg(Q:S));
     QSparams.std(i,1) = std(ecg(Q:S));
     QSparams.max(i,1) = max(ecg(Q:S));
     QSparams.min(i,1) = min(ecg(Q:S));
     QSparams.range(i,1) = QSparams.max(i,1)- QSparams.min(i,1);
     QSparams.L(i,1) = sum(abs(ecg(Q:S)));
     QSparams.L2range(i,1) = QSparams.L(i,1)/QSparams.range(i,1);
     QSparams.L2time(i,1) = QSparams.L(i,1)/((S-Q)/Fs);
     R = QSparams.range;
     
     AR = mean(R(end-5+1:end));
     
    %relR = QSparams.range/AR;
     if i~=1 && i~=N
         QSparams.minRR(i,1) = min(RR(i,1),RR(i+1,1));
         QSparams.minDist(i,1) = min((Q-QS(i-1,2))/Fs,(QS(i+1,1)-S)/Fs);
     else
         QSparams.minRR(i,1)= 0;
         QSparams.minDist(i,1)=0;
         
     end
 end
figure()
P1 = QSparams.range;
P2 = QSparams.minRR;
P3 = QSparams.L2time;
scatter3(P1,P2,P3);
QRSstruct_clear = struct('Q_start',Q_start,'R_peak',R_peak,'R_end',R_end);
r = max(QS);

[KSSV]

AR = mean(R(end-5+1:end));

This will throw error, if size of R is less than 5. You need to rethink on this.

[Abduljabbar Bamhel]

Thank you bro. , The size of R = [1390 1] and the same problem

Answer 1

[KSSV]

You should know that, the array indices in MATLAB should be positive integers or logicals. If not you will get this error.

Demo:

A = rand(10,1) ; 
A(1)   % no error, 1 is positive 
A(10)  % no error 10 is positve 
A(0)  % error index cannot be 0
A(-1)  % error indices cannot be negative 
%
idx = A>0.5 ; 
A(idx)   % no error, logical indexing 

Check in your code, where you are going wrong with the indices. Learn about debugging code. Stop at the line, debug and check the indices.

[Badavath Mohan]

good afternoon sir,please guide how to get 'ecgClear_1.mat' this data file

[Abduljabbar Bamhel]

Good afternoon I didn't understand , could you explain your question please? You need this data file?