# second largest peak value

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Kaleesh Bala 2019 年 6 月 12 日
コメント済み: Kaleesh Bala 2019 年 8 月 6 日
I'm getting the amp of second largest peak as correct but the time is wrong ?
How to obtain the second highest value X,Y from this and plot as already Y is correct ,X seems to be in wrong region?
signal(1,1:length(s.ans))=s.ans;
[PkAmp, PkTime] = findpeaks(abs(hilbert(signal(1,:))),t);
[highestPeak, indexOfHighestPeak] = max(PkAmp);
[a(1),b2]=max(abs(hilbert(signal(1,:))));
[a2(1),b6]=max(PkAmp(PkAmp<max(PkAmp))); % to get second largest peak value
% error is the time value calcluate and plotted wrong??
Highesttime(1,:) = t(b2);
Highest2time(1,:) = t(b6);
figure;
plot(t,(signal(1,:)),t,abs(hilbert(signal(1,:))),t(b2),a(1),'ro')
hold on
plot(PkTime, PkAmp, '^r', 'MarkerFaceColor','r')
xlim([0 0.0006]);ylim([-inf inf])
grid on
hold on,plot(t(b6),a2(1),'ko')
hold off

### 採用された回答

Alex Mcaulley 2019 年 6 月 12 日
To obtain the coordinates of the second peak you just need:
[PkAmp, PkTime] = findpeaks(abs(hilbert(signal(1,:))),t);
[~,idx] = sort(PkAmp,'descend');
PkAmp(idx(2)) %Amplitude of the second peak
PkTime(idx(2)) %Time of the second peak

#### 13 件のコメント

Alex Mcaulley 2019 年 6 月 13 日
Using cell array:
[PkAmp{k}, PkTime{k}] = findpeaks(abs(hilbert(signal(k,:))),t);
Kaleesh Bala 2019 年 8 月 6 日
Dear Alex
I have one more silly doubt in removing the index,I'm trying to find now the the largest time instead of Amp.So,I have used 'ascend' function which helps me to plot the the required time.
clc
clear all
close all
format long;
filenames={"30827"}
S(:,1) = [25 25 21.4 17.92 28.5 32.07 30 35 20 15];
S(:,2)= [10 15 8.5 12.07 8.5 12.07 5 5 5 5 ];
for i=1:numel(filenames)
end
for k=1:1:length(S)
[a(k),b2]=max(abs(hilbert(signal(k,:)))); % first peak amp & index
%finding the peaks
set(0,'DefaultFigureWindowStyle','docked')
[PkAmp, PkTime] = findpeaks(abs(hilbert(signal(k,:))),t);
[~,idx] = sort (PkTime, 'ascend' );
b6(k) = idx(4); % Index of the fourth largest peak
a6(k) = PkAmp(b6(k)); % Amplitude of the fourth largest peak
time4(k)= PkTime (b6(k)); % Time of the fourth largest peak
figure;
plot(t,(signal(k,:)),t,abs(hilbert(signal(k,:))),t(b2),a(k),'ro')
hold on;grid on
plot(PkTime, PkAmp, '^r', 'MarkerFaceColor','r')
%plotting 4th largest
hold on,plot(time4(k), a6(k),'ko')
hold off
end
As per the script it plots the 4th largest PKTime peak .But how to remove other PkTime based on highest "a" highest PKAmp and then recontinue to plot the graph by taking highest(PKAMP) as PKTIME 1?
Kaleesh Bala 2019 年 8 月 6 日 ### その他の回答 (1 件)

Steven Lord 2019 年 6 月 13 日
Use the islocalmax function with the 'MaxNumExtrema' option.