Islocalmin/max on an Animated Plot and Indices Problem

Question

Stella 2024-1-28

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2075286-islocalmin-max-on-an-animated-plot-and-indices-problem

评论： Stella 2024-1-30

TV_500ml.csv

Hi again!! I try to use islocalmin/max instead of findpeaks for my valleys and peaks, then use the previous answers for the same problem. But when I put the code in my for-loop code, it says "Array indices must be positive integers or logical values". Am I doing something wrong? because before I used findpeaks and call it even before the for-loop so it's not actually a real-time signal processing, so i put it in the for-loop and use local min/max instead. Also i multiplied my i to 100 because I want to plot it fastly, but also get problems on it.

%raw data from XYZ direction
NormChest = readtable('TV_1.5l_Hong.csv');                   %%%get the raw data 
C = table2array(NormChest(:,1));                               
x = table2array(NormChest(:,2));
y = table2array(NormChest(:,4));
z = table2array(NormChest(:,6));
total = table2array(NormChest(:,8));
time = C(:,1);
%--------------------------------------------------------------------------
% get relative acceleration
x = x - mean(x);
y = y - mean(y);
z = z - mean(z);
total = total - mean(total);
time = time - time (1);
%--------------------------------------------------------------------------
%design for low pass filter
fs = 1000; %sampling frequency
fc = 0.5; %cut-off frequency
order = 2;
[b1, a1] = butter (order, fc/(fs/2));
%--------------------------------------------------------------------------
% magnitude computation
mag = sqrt(x.^2+y.^2+z.^2);
figure (1)
plot (mag); axis tight;
mag  = filtfilt (b1, a1, mag);
%--------------------------------------------------------------------------
% Initialize the plot
figure(2);
h = plot(time(1), mag(1)); hold on;   % Start with the first data point
xlabel('Time'); axis tight;   
title('Real-time Signal Analysis'); 
h.XDataSource = 'x1';       % Set the data source properties for dynamic updating
h.YDataSource = 'y1';
for i = 2:length (time)
    % Update the data source
    x1 = time(1:i*100);
    y1 = mag(1:i*100);
    refreshdata(h, 'caller');
    drawnow;
    [TF1, P1] = islocalmin (mag);
    [TF2, P2] = islocalmax (mag);
    TF1 = -TF1;
    
    valid_vks_indices = P1 (time(P1) <= x1 (end));
    valid_pks_indices = P2 (time(P2) <= x1 (end));
    if ~isempty (valid_vks_indices)
        plot (time(valid_vks_indices), TF1(ismember(P1, valid_vks_indices)), 'or');
    end
    if ~isempty (valid_pks_indices)
        plot (time(valid_pks_indices), TF2 (ismember(P2, valid_pks_indices)), 'or');
    end
    pause(0.001);
end
hold off;

Thank you in advance for the help and I am still working on being good in Matlab, too.

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Answer 1

Dyuman Joshi 2024-1-28

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2075286-islocalmin-max-on-an-animated-plot-and-indices-problem#answer_1398586

The syntax of islocalmax (and islocalmin) is different than that of findpeaks.

Check the documentation for the appropriate syntax and incorporate the corrections accordingly.

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Dyuman Joshi 2024-1-30

Could you please share the data you are working with, so I can run your code and see what the issue is?

Stella 2024-1-30

Ohh !!Thank you!! I was actually having trouble with it for days and I want to have like the same (or closer) one with a labview code i made before where i also waited sometime before showing the peaks/valleys to make sure that they are really the peaks and valleys. I know I already have my labview code, but I am still new to matlab so I am not yet familiar with a lot of the functions. I also attached the example video of the labview code i made.

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