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How to use linear interpolation to resample taken data?

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Petch Anuwutthinawin
Petch Anuwutthinawin on 9 Jul 2021
Edited: Petch Anuwutthinawin on 10 Jul 2021
I am given a .csv file with three columns. The second column is dependent upon the first and third columns. The first column is chanel used to measure, second is voltage, third is time when the data was taken. I need to use linear interpolation to resample the voltage in the second column for each sensor with respect to the sensor and time. Each sensor took 17seconds of data in 1/120 second increments. I have written code to do a double variable interpolation for the data to 'synchronise' the data. It does not work. Do I have to somehow seperate each sensor into its own command first?
A=csvread('forcetest.csv')
Chanel=A(:,1)';
Voltage=A(:,2)';
Time=A(:,3)';
T=linspace(1,17,2040);
C=linspace(0,3,2040);
[Ti,Chi]=meshgrid(T,C);
interp2(Time,Chanel,Voltage,Ti,Chi,'linear')

Answers (1)

Walter Roberson
Walter Roberson on 9 Jul 2021
Yes, you need to separate by channel. You can do that by using
A3d = reshape(A, 3, [], size(A,2));
Voltages = permute(A3d(:,2,:), [1 3 2]);
Times = permute(A3d(:,3,:), [1 3 2]);
Voltages and Times are now both 2D arrays in which the 3 columns correspond to the three channels.
  1 Comment
Petch Anuwutthinawin
Petch Anuwutthinawin on 10 Jul 2021
How does this code fit into the main code? I thought something like this would work:
A=csvread('forcetest.csv');
A3d = reshape(A, 4, [], size(A,2)); %total time of recording?
Voltages = permute(A3d(:,2,:), [1 3 2]); %voltages seperated by column by chanel
Times = permute(A3d(:,3,:), [1 3 2]); %time seperated by chanel by column.
[Ti,Chi]=meshgrid(Times,A3d);
interp2(Times,Voltages,Ti,Chi,'linear');
%it dosent work?

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