# Checking a matrix for duplicates in specific row, removing the respective columns

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Claudius Simon Appel on 6 Aug 2020
So, I try to explain this.
I have a two-row matrix of values, [x;y], f.e.
x=[1 2 2 3 4 5 6 6 7]
y=[1 2 3 4 5 6 7 7 8]
being merged into the matrix:
d= [1 2 2 3 4 5 6 6 7;
1 2 3 4 5 6 7 7 8]
I then want to check this matrix for repeats in the first row & remove the respective columns, while saving the x values of the columns being removed as a seperate vector. So Output should be something like:
d=[1 3 4 5 7;
1 3 4 5 8]
x_cut=[2 6]
It should be noted that this would have to scan for multiple repeats of different values, as shown above.
Thank you.
Have a great day & stay safe
Claudius Appel

Bruno Luong on 6 Aug 2020
Edited: Bruno Luong on 6 Aug 2020
d= [1 2 2 3 4 5 6 6 7;
1 2 3 4 5 6 7 7 8]
dd = diff([nan,d(1,:),nan])==0;
remove = dd(1:end-1) | dd(2:end)
x_cut = unique(d(1,remove),'stable')
d(:,remove) = []
Claudius Simon Appel on 6 Aug 2020
Thank you.
That works perfectly.
Have a nice day & stay healthy.

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