set unique values in matrix for each column new to 0

Hi,

I want to set the dublicate values to zero:

The problem with this code is that it sets all duplicate values ​​to 0, even across columns. I want the duplicate values ​​to be removed only per column E.g. the error in my code:

0 0 0

0 0 1

1 0 2

2 1 3

2 2 4

2 2 4

is going to

0 0 0

0 0 0

1 0 0

2 0 3

0 0 4

0 0 0

I want

0 0 0

0 0 1

1 0 2

2 1 3

0 2 4

0 0 0

DOK_HQ10000_FD_zeitlich_neu= zeros(size(DOK_HQ10000_FD_zeitlich))
[~,pos] = unique(DOK_HQ10000_FD_zeitlich,'first')
DOK_HQ10000_FD_zeitlich_neu(pos)=DOK_HQ10000_FD_zeitlich(pos)

Answer 1

[Ruchika P Barman]

It is my understanding that you are trying to set the duplicate values to zero considering the elements columnwise in the matrix.

M = [0 0 0 ; 0 0 1; 1 0 2 ; 2 1 3 ; 2 2 4 ; 2 2 4]

M = 6×3

0 0 0 0 0 1 1 0 2 2 1 3 2 2 4 2 2 4

ans1=[];
[~,col]=size(M);
for c=1:col
    x=(M(:,c))';
    y = [x(1) diff(x)];
    y = find(y==0);
    z = x;
    z(y)=0;
    ans1 = [ans1;z];
end
ans1=ans1'

ans1 = 6×3

0 0 0 0 0 1 1 0 2 2 1 3 0 2 4 0 0 0

This should solve your problem, thank you.

[Frederik Reese]

Thanks for your help

Answer 2

[Bruno Luong]

It looks like your repeated elemenst are adjacent

M = [0 0 0 ; 0 0 1; 1 0 2 ; 2 1 3 ; 2 2 4 ; 2 2 4]

M = 6×3

0 0 0 0 0 1 1 0 2 2 1 3 2 2 4 2 2 4

M.*(diff([nan(size(M(1,:))); M],1,1)~=0)

ans = 6×3

0 0 0 0 0 1 1 0 2 2 1 3 0 2 4 0 0 0

Answer 3

[Bruno Luong]

This works for repeated elements that are in any order in the columns

M = randi(4,10,3)

M = 10×3

3 1 3 1 2 4 2 3 3 3 2 4 3 3 4 4 3 1 4 1 2 2 2 4 4 4 2 2 3 1

[m,n]=size(M);
IJ = cell(n,1);
v = cell(n,1);
for j=1:n
    [v{j},IJ{j}] = unique(M(:,j),'stable'); 
    IJ{j}(:,2)=j; 
end
accumarray(cat(1,IJ{:}), cat(1,v{:}), [m,n])

ans = 10×3

3 1 3 1 2 4 2 3 0 0 0 0 0 0 0 4 0 1 0 0 2 0 0 0 0 4 0 0 0 0

Answer 4

[Bruno Luong]

Another solution without assum^tion of M is sorted by column

M = randi(4,10,3)

M = 10×3

1 4 2 2 2 2 4 2 3 2 4 3 1 2 2 3 3 1 2 4 3 1 2 4 2 2 1 1 2 1

[m,n]=size(M);
[S,i] = sort(M);
M(i+(0:n-1)*m) = S.*~~[true(1,n);diff(S)]

M = 10×3

1 4 2 2 2 0 4 0 3 0 0 0 0 0 0 3 3 1 0 0 0 0 0 4 0 0 0 0 0 0