MATLAB Answers

second largest peak value

78 ビュー (過去 30 日間)
Kaleesh Bala
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?
s=load ('30827.mat');
signal(1,1:length(s.ans))=s.ans;
load t.mat;
[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

  0 件のコメント

Sign in to comment.

採用された回答

Alex Mcaulley
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

表示 10 件の古いコメント
Alex Mcaulley
Alex Mcaulley 2019 年 6 月 13 日
Using cell array:
[PkAmp{k}, PkTime{k}] = findpeaks(abs(hilbert(signal(k,:))),t);
Kaleesh Bala
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)
s(i)=load (filenames{i});
signal(i,1:length(s(i).ans))=s(i).ans; % loading the signals from the scanning pts
end
load t.mat; %loading the time values
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
Kaleesh Bala 2019 年 8 月 6 日
sa ve.PNG

Sign in to comment.

その他の回答 (1 件)

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

  0 件のコメント

Sign in to comment.


Translated by