How to apply butterworth filter to a few columns in a table

I have a 600X10 table. I want to apply butterworth filter for columns from 4 till 9 using this which gives me error:

tab_pelvis = filtfilt(b,a,tab_pelvis(:,4:9));
Error using filtfilt (line 81)
Invalid data type. Arguments must be double matrices.

Can you help please ?

Answer 1

[Star Strider]

Try something like this —

tab_pelvis = filtfilt(b,a,tab_pelvis{:,4:9});

Note the curly braces {}. This will reference the contents of the table rather than the table itself, which is what the parentheses () do here.

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Answer 2

[Mathieu NOE]

hello

you can apply your filter on a numerical array , not a table , so convert it using table2array

tab_pelvis_array = table2array(tab_pelvis);
[b,a] = butter(2,0.2,'low');           % IIR filter design example
tab_pelvis_array_filtered = filtfilt(b,a,tab_pelvis_array(:,4:9));