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Brace indexing is not supported for variables of this type.

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reference_data=readtable('reference_150ohmn.csv');
  2 Comments
Christie Joy Pascua
Christie Joy Pascua on 23 Apr 2021
That wasn't supposed to be there, I had forgot to delete it because it didn't work

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Accepted Answer

Star Strider
Star Strider on 23 Apr 2021
The problem is immediately apparent on viewing the contents —
ViewContents = readcell('https://www.mathworks.com/matlabcentral/answers/uploaded_files/594720/reference_150ohmn.csv')
ViewContents = 10017×2 cell array
{'Model' } {'MDO3024' } {'Firmware Version' } {[ 1.1400]} {'Waveform Type' } {'ANALOG' } {'Point Format' } {'Y' } {'Horizontal Units' } {'s' } {'Horizontal Scale' } {[ 1]} {'Horizontal Delay' } {[ 0]} {'Sample Interval' } {[ 1.0000e-03]} {'Record Length' } {[ 10000]} {'Gating' } {'0.0% to 100.0%'} {'Probe Attenuation'} {[ 1]} {'Vertical Units' } {'V' } {'Vertical Offset' } {[ 0]} {'Vertical Scale' } {[ 0.0500]} {'Vertical Position'} {[ 5]} {'Label' } {1×1 missing }
Try this instead: —
reference_data=readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/594720/reference_150ohmn.csv', 'HeaderLines',16);
reference_data.Properties.VariableNames = {'TIME','REF1'};
reference_time=reference_data.TIME;
reference_voltage=reference_data.REF1;
Ts = mean(diff(reference_time))
Ts = 1.0000e-03
Fs = 1/Ts
Fs = 1.0000e+03
% % % % % % % % THE COMMENTED-OUT SECTION IS NOT NECESSARY, SO DELETE IT —
% x = zeros(1, 10000);
% for i=1:size(reference_time,1)
% reference_time_double=str2double(cell2mat(reference_time(i)))
% end
% reference_time_double=reference_time_double+5;
% x1 = zeros(1, 10000);
% for i=1:1:size(reference_time,1)
% for reference_voltage_double=str2double(cell2mat(reference_voltage(i)))
% end
% if isnumeric(i{1}) || ischar(i{1}) || islogical(i{1}) || isstruct(i{1})
% x1(i)=1:1:size(reference_time,1);
% end
% end
filterred_reference=bandpass(reference_voltage,[0.51,59],Fs); % bandpass filtering
notch_frequencies=[58 61];
Sig_notch_reference=bandstop(filterred_reference,notch_frequencies,Fs); % notch filtering
f1=figure('units','normalized','outerposition',[0 0 1 1]);
subplot(2,1,1)
plot(reference_time,reference_voltage,'k','LineWidth',1)
grid on
title('Reference Electrode, before filtering')
set(gca,'FontSize',20);
subplot(2,1,2)
plot(reference_time,Sig_notch_reference,'k','LineWidth',1)
title('Reference Electrode, after filtering')
grid on
set(gca,'FontSize',20);
The filtering obviously needs work. Since I have no idea what you want to do, I will leave that to you.
I would apply the 60 Hz notch (bandstop) filter first, then use a bandpass filter with a bandwidth of 1 Hz to 100 Hz to filter the EKG. That willl remove the baseline wander and any remaining high-frequency noise without removing necessary parts of the EKG trace itself.
.
  4 Comments
Star Strider
Star Strider on 25 Apr 2021
My pleasure!
If my Answer helped you solve your problem, please Accept it!
.

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