MATLAB: How to segment the signal based on amplitude change.

MATLABsignal segmentation

Attached herewith a signal image and dataset (.mat file). I have to segment the signal with respect to amplitue and extract the time duration of each segment.

Your help will be highly appreciated.

Thank you.

Best Answer

Use the findchangepts (link) function (introduced in R2016a):

D = load('t1.mat');
t1 = double(D.t1);
[cp,res] = findchangepts(t1(:,3), 'MaxNumChanges',2, 'Statistic','std');
figure
plot(t1(:,1), t1(:,3))
hold on
plot(repmat(t1(cp,1),1,2)', repmat(ylim',1,numel(cp)), 'LineWidth',2)
hold off
grid

See the documentation for the function for detailks on the various options.

Related Solutions

MATLAB: How to automatic segmentation signal

The findchangepts (link) function (introduced in R2016a) is perfect for this:

D = load('matlab.mat');
data = D.data;
Fs = D.fs;
t = linspace(0, 1, numel(data))/Fs;
cp = findchangepts(data, 'Statistic','std', 'MinDistance',2E+3, 'MaxNumChanges',7);
figure
plot(t, data)
hold on
YL = ylim;
plot([t(cp); t(cp)], YL(:)*ones(1,numel(cp)), '-r', 'LineWidth',1)
hold off

producing:

how to automatic segmentation signal - 2019 01 22.png

The ‘cp’ vector are the change points corresponding to the vertical red lines in the plot. The findchangepts function takes about 15 seconds to complete this (on my desktop, using tic and toc),

Experiment to get the result you want.

MATLAB: Hi, how can I divide this signal into 3 segments? The first segment I want to be the signal before the major peak, the second segment would be the major peak and the last segment would be the signal after the peak.

One approach:

The Code —

D = load('signals (1).mat');
Signal = D.Signal;                                                                                      % Get ‘Signal’
N = length(Signal);
t = linspace(0, 1, N) * N;                                                                              % Create Time Vector
[pk,loc] = findpeaks(Signal, 'MinPeakHeight',1);                                                        % Determine Indices Of Various Components
[trofs,trlocs] = findpeaks(-Signal);
ltidx = find(trlocs < loc, 1, 'last');
gtidx = find(trlocs > loc, 1, 'first');
Out{1} = {Signal(1:trlocs(ltidx)); Signal(trlocs(ltidx)+1:trlocs(gtidx)-1); Signal(trlocs(gtidx):end)}; % ‘Signal’ Cell Array
Out{2} = {t(1:trlocs(ltidx)); t(trlocs(ltidx)+1:trlocs(gtidx)-1); t(trlocs(gtidx):N)};                  % ‘t’ Cell Array
figure
plot(Out{2}{1}, Out{1}{1}, 'r')
hold on
plot(Out{2}{2}, Out{1}{2}, 'g')
plot(Out{2}{3}, Out{1}{3}, 'b')
hold off
grid

The Plot —

Best Answer

Related Solutions

MATLAB: How to automatic segmentation signal

MATLAB: Hi, how can I divide this signal into 3 segments? The first segment I want to be the signal before the major peak, the second segment would be the major peak and the last segment would be the signal after the peak.

Related Question