fix the indices of the matrix

I really need help to fix the indices of the for loop to run the QRS detection.

I updated the file, this code run with the file ech_60hz_200 that I downl;oad from bio bank, but it cannot run with the code ecg_sbj1 that I recorded in the lab room. it returned 'Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.' Please help me fix this indices in the for loop to run the code

close all;clear;clc;
load('ecg_sbj1.mat');
sig=ecg;
N=length(sig);
fs=200;
t=[0:N-1]/fs;
title('Original Signal')

b=1/32*[1 0 0 0 0 0 -2 0 0 0 0 0 1];
a=[1 -2 1];
sigL=filter(b,a,sig);

b=[-1/32 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1/32];
a=[1 -1];
sigH=filter(b,a,sigL);

b=[1/4 1/8 0 -1/8 -1/4];
a=[1];
sigD=filter(b,a,sigH);


sigD2=sigD.^2;

signorm=sigD2/max(abs(sigD2));

 
h=ones(1,31)/31;
sigAV=conv(signorm,h);
sigAV=sigAV(15+[1:N]);
sigAV=sigAV/max(abs(sigAV));

treshold=mean(sigAV);
P_G= (sigAV>0.01);

difsig=diff(P_G);
left=find(difsig==1);
raight=find(difsig==-1);


left=left-(6+16);
raight=raight-(6+16);


for i=1:length(left);
   
    [R_A(i) R_t(i)]=max(sigL(left(i):raight(i)));
    R_t(i)=R_t(i)-1+left(i) %add offset
   
    [Q_A(i) Q_t(i)]=min(sigL(left(i):R_t(i)));
    Q_t(i)=Q_t(i)-1+left(i)
  
    [S_A(i) S_t(i)]=min(sigL(left(i):raight(i)));
    S_t(i)=S_t(i)-1+left(i)
    
    [P_A(i) P_t(i)]=max(sigL(left(i):Q_t(i)));
    P_t(i)=P_t(i)-1+left(i)
    
    [T_A(i) T_t(i)]=max(sigL(S_t(i):raight(i)));
    T_t(i)=T_t(i)-1+left(i)+47
    
   
end


figure;plot(t,sigL,t(Q_t),Q_A,'*g',t(S_t),S_A,'^k',t(R_t),R_A,'ob',t(P_t),P_A,'+b',t(T_t),T_A,'+r');
for i=1:((length(P_t))-1)
    
    HRV=P_t(i+1)-P_t(i)
end

    

[Davide Masiello]

Please give more info about what is there to fix.

[Tu Nguyen]

The problem is in the for loop, it return 'Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.'. I dont know why

Answer 1

[Walter Roberson]

In each case your left values are greater than your corresponding right values, so left(i):right(i) is always empty.

[Tu Nguyen]

The problem is when I load the raw data ecg grom biobank, size 476x1, the code is running, but when I load the ecg data that I recorded in the lab room with size 12000x1, it does not run. I dont know the error said: 'Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.'

Please help me fix that error

[Walter Roberson]

Immediately before your

for i=1:length(left);

statement, put in

    disp([left, right])

You will see that in every case, the value in the left column is greater than the value in the right column. You use those values as the start and stop indices left(i):right(i) but with left being greater than right, that is empty. Computing with empty gives you empty, so the right hand side of the computation is empty. You are trying to store that emptiness into a scalar location, which is a size mismatch.

You are assuming that difsig==1 always occurs before difsig==-1 but what if that is not the case?? What if the signal zags first instead of zigging first?

Answer 2

[VBBV]

close all;clear;clc;
load('ecg_sbj1.mat')
sig=ecg

sig = 12000×1

31 30 32 32 31 30 31 32 31 30

N=length(sig);
fs=200;
t=[0:N-1]/fs

t = 1×12000

0 0.0050 0.0100 0.0150 0.0200 0.0250 0.0300 0.0350 0.0400 0.0450 0.0500 0.0550 0.0600 0.0650 0.0700 0.0750 0.0800 0.0850 0.0900 0.0950 0.1000 0.1050 0.1100 0.1150 0.1200 0.1250 0.1300 0.1350 0.1400 0.1450

b=1/32*[1 0 0 0 0 0 -2 0 0 0 0 0 1];
a=[1 -2 1];
sigL=filter(b,a,sig)

sigL = 12000×1

0.9688 2.8750 5.7812 9.6875 14.5625 20.3750 25.2188 29.1875 32.1250 34.0000

b=[-1/32 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 -1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1/32]

b = 1×33

-0.0312 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1.0000 -1.0000 0 0 0 0 0 0 0 0 0 0 0 0

a=[1 -1];
sigH=filter(b,a,sigL);

b=[1/4 1/8 0 -1/8 -1/4];
a=[1];
sigD=filter(b,a,sigH)

sigD = 12000×1

-0.0076 -0.0338 -0.0902 -0.1847 -0.3175 -0.4885 -0.6821 -0.8761 -1.0477 -1.1812

sigD2=sigD.^2;

signorm=sigD2/max(abs(sigD2));

 
h=ones(1,31)/31;
sigAV=conv(signorm,h);
sigAV=sigAV(15+[1:N]);
sigAV=sigAV/max(abs(sigAV));

treshold=mean(sigAV);
P_G= (sigAV>0.01);

difsig=diff(P_G);
left=find(difsig==1);
raight=find(difsig==-1);


left=left-(6+16)

left = 148×1

107 116 172 257 328 410 490 577 655 741

raight=raight-(6+16)

raight = 148×1

94 112 129 246 281 401 439 564 593 729

max(left)

ans = 11929

max(raight)

ans = 11871

min(left)

ans = 107

min(raight)

ans = 94

for i=1:length(left);
   
    if raight(i) < left(i)
    [R_A(i) R_t(i)]=max(sigL(raight(i):left(i)));
    R_t(i)=R_t(i)-1+left(i); %add offset
    else 
    [R_A(i) R_t(i)]=max(sigL(left(i):raight(i)));
    R_t(i)=R_t(i)-1+left(i); %add offset
    end 
   
    if left(i) < R_t(i)
    [Q_A(i) Q_t(i)]=min(sigL(left(i):R_t(i)));
    Q_t(i)=Q_t(i)-1+left(i);
    else
    [Q_A(i) Q_t(i)]=min(sigL(R_t(i):left(i)));
    Q_t(i)=Q_t(i)-1+left(i);
    end 
    
    if raight(i) < left(i)
    [S_A(i) S_t(i)]=min(sigL(raight(i):left(i)));
    S_t(i)=S_t(i)-1+left(i);
    else 
    [S_A(i) S_t(i)]=min(sigL(left(i):raight(i)));
    S_t(i)=S_t(i)-1+left(i);
    end 
    
    if left(i) < Q_t(i)
    [P_A(i) P_t(i)]=max(sigL(left(i):Q_t(i)));
    P_t(i)=P_t(i)-1+left(i);
    else 
    [P_A(i) P_t(i)]=max(sigL(Q_t(i):left(i)));
    P_t(i)=P_t(i)-1+left(i);
    end 
    
    if S_t(i) < raight(i)
    [T_A(i) T_t(i)]=max(sigL(S_t(i):raight(i)));
    T_t(i)=T_t(i)-1+left(i)+47;
    else 
    [T_A(i) T_t(i)]=max(sigL(raight(i):S_t(i)));
    T_t(i)=T_t(i)-1+left(i)+47;
    end 
    
   
end

% compare two plots differently 
subplot(211)
plot(t(1:length(Q_t)),Q_A,'*g',t(1:length(S_t)),S_A,'^k',t(1:length(R_t)),R_A,'ob',t(1:length(P_t)),P_A,'+b',t(1:length(T_t)),T_A,'+r');
subplot(212)
plot(t,sigL)

% title('Original Signal')

for i=1:((length(P_t))-1)
    
    HRV=P_t(i+1)-P_t(i);
end

You need to use a condition to segregate data in lower to higher order in data arrays for which you add offsets .

[Tu Nguyen]

Can you help me? I want the QRS on the signal sigL, I plot but it showed 'Index exceeds the number of array elements (12000).'