removal of doubles (both values)

Hi all,

I have an nx3 matrix of values. The values are sorted and there are duplicates(never more than 1 duplicate).

If duplicates occur, I would like to replace both duplicates with a place holder..ex(0,0,0) ex

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

ans
1 1 1 
0 0 0 
0 0 0 
3 3 3 
0 0 0 
0 0 0

Any thoughts would be very helpful, thanks

Answer 1

[Image Analyst]

I'm sure someone will come up with a one-liner, but here's a three-liner way

data = [1 1 1; 2 2 2; 2 2 2; 3 3 3; 4 4 4; 4 4 4; 4 4 4]

duplicateRows = diff(data(:,1)) == 0
duplicateRows = [duplicateRows;0] | [0; duplicateRows]
data(duplicateRows,:) = 0

[matt]

This works great! Thank you very much

Answer 2

[Fangjun Jiang]

This is one way to do it.

a=[1 1 1 
2 2 2 
2 2 2 
3 3 3 
4 4 4 
4 4 4];

[ua,indI,indJ]=unique(a,'rows');
DupRows=setdiff(1:size(a,1),indI);
index=[DupRows,DupRows+1];
a(index,:)=0;

[matt]

This is also a big help, thanks!