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Bring some signals to the same start value and end value

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Daniel Sedlaczek
Daniel Sedlaczek on 24 Nov 2020
Edited: Daniel Sedlaczek on 26 Nov 2020
Hello,
I need some help. I want to bring some Signals to the same start end value. How I can do this quickly and easy?
Here is our code to plot the signals in one plot:
clear all
close all
F = 2000;
load('Spiro_4.mat');
data4 = data;
Atemfluss4 = data(1:end,1);
Volumen4 = data(1:end,2);
F = 2000; % sampling frequency
T4= 1/F; %Periodendauer
t4= ([0:T4:25.889]); % time vector
load('Spiro_3.mat');
data3 = data;
Atemfluss3 = data(1:end,1);
Volumen3 = data(1:end,2);
F = 2000; % sampling frequency
T3= 1/F; %Periodendauer
t3= ([0:T3:28.444999]); % time vector
load('Spiro_2.mat');
data2 = data;
Atemfluss2 = data(1:end,1);
Volumen2 = data(1:end,2);
F = 2000; % sampling frequency
T2= 1/F; %Periodendauer
t2= ([0:T2:25.979999]); % time vector
load('Spiro_1.mat');
data1 = data;
Atemfluss1 = data(1:end,1);
Volumen1 = data(1:end,2);
F = 2000; % sampling frequency
T1= 1/F; %Periodendauer
t1= ([0:T1:33.414]); % time vector
figure;
plot(t1,Volumen1,t2,Volumen2,t3,Volumen3,t4,Volumen4);
ylabel('Volume in litres');
xlabel('Zeit in s');
Thank you for support.
[EDITED, Jan, Code formatted]

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dpb
dpb on 25 Nov 2020
Well then, post the Answer, don't just leave it hanging...altho never did fully define the solution wanted.
Daniel Sedlaczek
Daniel Sedlaczek on 26 Nov 2020
I have solve it with a Best fit line like this:
x1=1;
x2=length(VolumenDeTrend);
y1=VolumenDeTrend(x1);
y2=VolumenDeTrend(x2);
m = (y2-y1)/(x2-x1);
b = y1-(m*x1);
x=[x1:1:x2];
z = m*x+b;
g = z';
VolumenDA = VolumenDeTrend - g;

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Answers (2)

Mathieu NOE
Mathieu NOE on 24 Nov 2020
hello
if you want all data to start and stop at the same values , you can do that : it works even sampling rates are different
if it 's ok for you I'll be glad if you would accept my answer
% define common start and stop time values
start = 0;
stop = 1; % for example
ind1 = find(t1>=start & t1<=stop)
ind2 = find(t2>=start & t2<=stop)
ind3 = find(t3>=start & t3<=stop)
ind4 = find(t4>=start & t4<=stop)
figure;
plot(t1(ind1),Volumen1(ind1),t2(ind2),Volumen2(ind2),t3(ind3),Volumen3(ind3),t4(ind4),Volumen4(ind4));
ylabel('Volume in litres');
xlabel('Zeit in s');

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dpb
dpb on 24 Nov 2020
Presuming it is to just stretch the shorter to the same time as the longest, something like:
y1=randn(size(t1)); Y1=movmean(y1,6000);
y4=randn(size(t4)); Y4=movmean(y4,6000);
plot(t1,Y1,t4,Y4)
% sample data completed, "stretch" Y4 to length/time of Y1
Y4adj=resample(Y4,numel(t1),numel(t4));
% and show result
hold on
plot(t1,Y4adj)
legend('Y1','Y4','Y4adj')
produced
A little noisy signal but can see stretched the original red curve out to same length as the blue one. Rinse and repeat.

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