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making different signals equal in length

Asked by Lisa Justin on 3 Dec 2012
Latest activity Commented on by Walter Roberson
on 1 Jun 2015

Hi, I am working with a set of data and i need all of them to be the same length. how can i do this?

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3 Answers

Answer by Jan Simon
on 3 Dec 2012
 Accepted answer

It depends. As said already you can crop the longer ones, pad the shorter ones or apply an interpolation. For the latter there are linear, cubic, spline, bsline, trigonometric and more complicated interpolation methods.

  2 Comments

aliya
on 1 Jun 2015

What if we have multiple signals from a database of different sizes. how to make their length equal?

Walter Roberson
on 1 Jun 2015

Find the maximum of their lengths, say maxlen. Then for each,

ifft(fft(TheSignal),maxlen)

Answer by Walter Roberson
on 3 Dec 2012
S1 = size(FirstMatrix);
S2 = size(SecondMatrix);
MaxS = max(S1, S2);
if MaxS(1) > S1(1); FirstMatrix(end+1:MaxS(1), :) = 0; end
if MaxS(2) > S1(2); FirstMatrix(:, end+1:MaxS(2)) = 0; end
if MaxS(1) > S2(1); SecondMatrix(end+1:MaxS(1), :) = 0; end
if MaxS(2) > S2(2); SecondMatrix(:, end+1:MaxS(2)) = 0; end

You can simplify this a bit if you are using vectors and you know the orientation of the vectors.

  2 Comments

Walter Roberson
on 3 Dec 2012

Ah... did you want to do this by clipping the longer ones to the length of the shorter?

Lisa Justin on 3 Dec 2012

yes exactly. But then i lose some relevant part of the signal which is not good either. I am a bit unsure how best to make all the length equal. they are about 600 files


Answer by Muruganandham Subramanian on 3 Dec 2012

Can you provide the data? you can do it by adding zeros, ones, any desirable data to the data having minimum sizes from data having maximum sizes by initializing max. data length caustiously..

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