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Filter time-variant data and reduce its length

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zhi liu
zhi liu on 26 Apr 2020
Commented: Ameer Hamza on 26 Apr 2020
Hi experts,
I have a time-variant test data. The 1st column is time, and the 2nd column is data. There is a serious fluctuation of it. I want to filter the data and at the same time want to reduce its length.
Could somebody guide me how to do this? Thank you!

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Accepted Answer

Ameer Hamza
Ameer Hamza on 26 Apr 2020
It seems like you are trying to plot step-response of a system. Try something like this
data = load('data.csv');
t = data(1:100,1);
y = data(1:100,2);
y = smoothdata(y, 'sgolay', 20);
plot(t, y)
It reduces the length by taking the first 100 elements and smoothening the signal.

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zhi liu
zhi liu on 26 Apr 2020
I want to get the full-response but a shorter data is needed. Is there suitable method? Thank you!
Ameer Hamza
Ameer Hamza on 26 Apr 2020
Yes, The system reaches its steady-state after a few seconds. The rest of the data is redundant. This gives the full response of the system.

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More Answers (1)

Thiago Henrique Gomes Lobato
Take a look at medfilt1 and/or movmean. They sould help you reduce the fluctuations. To reduce the data length you just index the time you want:
idx1 = 100;
idx2 = 900;
Data = Data(idx1:idx2,:); % Data = Length x 2 matrix
In this example your data will go only from meausurement point 100 to measurement point 900.

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