Adding a new column to a matrix under certain constraints.

Hi!

I'm having trouble coming up with how to get what I want. I think a picture will best explain what I'm trying to do.

I want to add a new column to my matrix the following way. It starts counting from 1 and changes everytime the two columns are no longer the same.

So for example for the first three rows both columns are the same, at row 4 they change so the counter changes to 2, at row 5 they change again so once again the counter changes to 3 etc.

Any help is greatly appreciated!

Answer 1

[Abderrahim. B]

Hi!

This a way to do this logic you described in the question, maybe there better ways !

clear

% Dummy data
wp = [[ones(7,1); 2*ones(2,1); ones(8,1)] , randi(3, 17,1) ] ;

% Preallocation and setting first element of the 3rd column to 1
wpDiff = diff(wp) ;
wpNewCol    = zeros(length(wp), 1) ;
wpNewCol(1) = 1 ;

% Algorithm
for ii = 2:length(wpNewCol) 
    if  ~ any(wpDiff(ii-1, :))
       wpNewCol(ii ) = wpNewCol(ii - 1) ;
    else
       wpNewCol(ii) =  wpNewCol(ii -1) + 1; 
    end

end

% New wp
new_wp = [wp, wpNewCol] 

new_wp = 17×3

1 3 1 1 2 2 1 2 2 1 2 2 1 2 2 1 3 3 1 3 3 2 1 4 2 2 5 1 2 6

Hope this helps

[Jonatan Juslin]

This is exactly what I wanted, thank you!