필터 지우기
필터 지우기

Find the width of a peak

조회 수: 7 (최근 30일)
Samridh Jain
Samridh Jain 2022년 7월 3일
편집: Star Strider 2022년 7월 3일
I have a csv data of an impact collected. I would like to measure the duration/width of the main peak.
The deepest peak is the main, but then there may be other peaks prior and another peak beginning before reaching the base.
As I am dealing with multiple peaks, how do I measure the width of just the beginning of deepest peak to its end?
The first image below is the graph of the impact. Second image zooms into the second peak beginning before reaching zero and the width i would like to find. Also attaching the raw csv data for reference.
Thanks a lot!

채택된 답변

Star Strider
Star Strider 2022년 7월 3일
Try something like this —
T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/1053640/j1%20a30.csv', 'VariableNamingRule','preserve')
T1 = 5953×9 table
__time /leptrino_force_torque/force_torque/header/seq /leptrino_force_torque/force_torque/header/stamp /leptrino_force_torque/force_torque/wrench/force/x /leptrino_force_torque/force_torque/wrench/force/y /leptrino_force_torque/force_torque/wrench/force/z /leptrino_force_torque/force_torque/wrench/torque/x /leptrino_force_torque/force_torque/wrench/torque/y /leptrino_force_torque/force_torque/wrench/torque/z __________ ______________________________________________ ________________________________________________ __________________________________________________ __________________________________________________ __________________________________________________ ___________________________________________________ ___________________________________________________ ___________________________________________________ 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.03 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.03 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.03 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.03 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.03 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.03 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.9 0.066 -0.03 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.925 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.925 0.066 -0.0294 0.102 1.6568e+09 1.9251e+06 1.6568e+09 0.475 3.7 2.925 0.066 -0.0294 0.102
VN = T1.Properties.VariableNames.';
t = T1{:,1};
f = T1{:,[4 5 6]};
x = t;
y = f(:,3);
[pks,plocs] = findpeaks(-y, 'MinPeakProminence',20); % Desired Peak & Index
[vys,vlocs] = findpeaks(y, 'MinPeakProminence',0.1); % Valleys & Indices
[vlc,ixv] = mink(abs(vlocs-plocs),2); % Choose Two Closest Valleys To Desired Peak
vlcs = plocs + [1; -1].*vlc; % Calculate Indices
idxr = vlcs(2) : vlcs(1); % Initial Index Range
figure
plot(x(idxr), y(idxr)) % Plot Desired Peak Region
hold on
plot(t(vlcs), y(vlcs), '^r')
hold off
grid
title('Isolated')
figure
plot(t, y)
hold on
plot(t(vlcs), y(vlcs), '^r')
hold off
grid
title('In Context')
xlim([-1 1]*1E-1 + t(plocs))
text(t(plocs), -5, sprintf('\\leftarrow %.6f \\rightarrow', diff(t(vlcs))), 'Horiz','center', 'Vert','middle', 'FontSize',8)
This uses code I recently wrote to define the valleys around a peak rather than the reverse, as required here. I changed it slightly for this problem.
.
  댓글 수: 4
Samridh Jain
Samridh Jain 2022년 7월 3일
Sorry to bother further...how would I be able to measure the width if it's a max peak? Above file deals with negative values, but after finding the resultant force, the values become positive. Attaching the MATLAB file for reference. I find the resultant of x,y,z so all values become positive.
Star Strider
Star Strider 2022년 7월 3일
편집: Star Strider 2022년 7월 3일
No worries!
The positive peak code would work similarly. See: How can I get the mean data from under the graphs?
This was the original approach that I wrote this code for. I adapted it for the negative version with your data. The area code is similar as well, although it would likely need to be adapted to work with your data, similar to what I did with the negative peak areas.
EDIT — (3 Jul 2022 at 17:58)
For a specific peak, the code would be something like this —
x = (920 : 980).'; % Create Data (Column)
y = sinc((x-mean(x))/5); % Create Data (Column)
figure
plot(x, y)
grid
[pks,plocs] = findpeaks(y, 'MinPeakProminence',1); % Desired Peak & Index
[vys,vlocs] = findpeaks(-y, 'MinPeakProminence',0.1); % Valleys & Indices
[vlc,ixv] = mink(abs(vlocs-plocs),2); % Choose Two Closest Valleys To Desired Peak
vlcs = plocs + [-1; 1].*vlc; % Calculate Indices
idxr = vlcs(1) : vlcs(2); % Initial Index Range
hold on
plot(x(idxr([1 end])), y(idxr([1 end])), 'vr')
hold off
figure
plot(x(idxr), y(idxr)) % Plot Desired Peak Region
hold on
plot(x(idxr([1 end])), y(idxr([1 end])), 'vr')
hold off
grid
The area calculation would be similar to the negative peak code.
.

댓글을 달려면 로그인하십시오.

추가 답변 (1개)

Jonas
Jonas 2022년 7월 3일
do you just want to measure the peak width of this data set only? if yes, i should be telatively easy locating the peak with min() and the locating start and end of it by using e.g. islocalmax() to find last peak before main peak and first peak after main peak

카테고리

Help CenterFile Exchange에서 Descriptive Statistics에 대해 자세히 알아보기

제품


릴리스

R2022a

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by