combining 2 ECG signal into 1

I'm tring to merg 2 ECG signal into one (with same sampling rate), however, at the merging point, there is some error. I can't figure it out. could someone please help, appreciated. my code and the figure are attached.

clear all

close all

dataaf=load("AF2.mat"); % AF signal

xaf=dataaf.val(1,:);

xaf=detrend(xaf)';

datan=load("normal2.mat"); % Normal

xn=datan.val(1,:);

xn=detrend(xn)';

%xnr=resample(xn,250,128); % resample raw signal

xc=[xn;xaf];

Fs = 128;

t = (0:length(xc)-1)/Fs; %time value of any sample = [sample no./Fs]

plot(t,xc)

xlabel('Time [s]')

% hold on

pause

Answer 1

[Star Strider]

Unless the row vectors ‘xn’ and ‘xaf’ have the same number of elements, the vertical concatenation to produce ‘xc’ is going to fail:

xc=[xn;xaf];

Horizontrally concatenating them (note the substitution of the comma for the semicolon) however will work:

xc=[xn,xaf];

.

[DILINUIER AIERKEN]

thank you so much, that make sense!

Is there any other way I could vertical concatenation these two signal?

[Star Strider]

My pleasure!

To vertically concatenate them, the must have the same lengths. Probably the easiest way to do that would be to zero-pad the end of the shorter vector. This will avoid resampling either vector, so both vectors retain their original sampling frequencies, and will avoid shortening the longer vector and removing data from it.

Perhaps do something like this —

xaf = randn(1,6);                                   % Create Signal
xn = randn(1,9);                                    % Create Signal
maxlen = max(cellfun(@numel, {xaf,xn}))             % Return Maximum Length

maxlen = 9

xc = zeros(2,maxlen)                                % Define 'xc'

xc = 2×9

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

xc(1,1:numel(xn)) = xn;                             % Fill 'xc'
xc(2,1:numel(xaf)) = xaf                            % Fill 'xc'

xc = 2×9

0.2878 0.0987 0.2228 -0.0642 -0.3257 0.7359 1.6295 -0.7933 0.8884 0.0474 -0.6968 -0.3125 0.1659 -1.1220 1.6277 0 0 0

Fs = 128;
t = (0:maxlen-1)/Fs; %time value of any sample = [sample no./Fs]

figure
plot(t,xc)
xlabel('Time [s]')
legend('xc(1,:)','xc(2,:)', 'Location','best')

This appears to me to be the most efficient way to verticaly concatenate them if they originally have different lengths.

.

[DILINUIER AIERKEN]

Thank you !

[Star Strider]

As always, my pleasure!