Finding peak value and peak arrival time from a time-domain plot and store it into a matrix.

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Syed Farez
Syed Farez 2018-5-18
评论： Syed Farez 2018-5-19
I have 360 differential signals to be processed through SVM. How do I extract peak value and peak arrival time from time-domain plot of each signal and store it in a single matrix? Below is my code.
% load a .mat file
load ('Defect_Signals_with_Labels.mat');
fs = 100000;
for j = 1:360
x = SurfaceDifferential(:,j);
% set time to be in milliseconds
time = ( 0: length(x)-1) / fs;
% plot frequency in time domain
figure(2);
plot(time, x);
xlabel('Time (s)');
ylabel('Magnitude (Gauss)');
grid on;
end

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采纳的回答

Sandro Lecci
Sandro Lecci 2018-5-18
编辑：Sandro Lecci 2018-5-18
Hi Syed,
are you looking for the max value and its index ?
peakValues = NaN(360, 2); %column 1 is peak value, column 2 is arrival time
for j = 1:360
% Extract the time-series data
x = SurfaceDifferential(:,j);
% set time to be in milliseconds
time = ( 0: length(x)-1) / fs;
%extract max and its location from the timeseries data
[xMax, xIdx] = max(x);
peakValues(j,1) = xMax;
peakValues(j,2) = time(xIdx); %to get the value in milliseconds
%plot...
end
best, Sandro
  4 个评论
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Guillaume
Guillaume 2018-5-18
Sandro makes some good points in his latest comment.
I just want to point out that the loop in the answer is completely unnecessary and the whole lot can be replaced by just:
[peakvalues, where] = max(SurfaceDifferential);
correspondingtime = time(where);
Syed Farez
Syed Farez 2018-5-19
That's a very good and helpful information for me. I think the max value will give a better result for my work. Thank you very much for this Sandro & Guillaume. Much appreciated indeed.

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