identify duplicate entries of matrix and delete

Hello,

I have an array as follows. I need to identify duplicate row values from column 1 to 5 and delete the row with negative 7th column element and keep the other row. For example, here row values 5 and 6:

1973  4  1  13  1,34  1,31  0,95  0,35
1973  4  2  2  1,17  1,14  0,85  0,29
1973  4  2  8  -0,5  -0,53  -0,81  0,28
1973  4  2  15  1,54  1,51  1,03  0,48
1973  4  2  18  1,82  1,79  1,03  0,76
1973  4  2  18  1,82  1,79  -0,54  2,33
1973  4  3  3  2,24  2,21  1,02  1,19
1973  4  3  15  1,73  1,70  1,15  0,54

The resulting matrix

1973  4  1  13  1,34  1,31  0,95  0,35
1973  4  2  2  1,17  1,14  0,85  0,29
1973  4  2  8  -0,5  -0,53  -0,81  0,28
1973  4  2  15  1,54  1,51  1,03  0,48
1973  4  2  18  1,82  1,79  1,03  0,76
1973  4  3  3  2,24  2,21  1,02  1,19
1973  4  3  15  1,73  1,70  1,15  0,54

Any help?

Answer 1

[Star Strider]

Assigning your matrix to variable ‘M’, this should do what you want:

[~,idx] = unique(M(:,1:5), 'rows', 'stable');
Result = M(idx,:);

[Poulomi Ganguli]

Thanks, its working in this case. Just curious, what is the function of 'rows' 'stable' & does it able to eliminate specifically negative values at column 7 corresponding to particular rows? since I have just copied a small part of a big array.

[Star Strider]

My pleasure.

The 'rows' argument tells the unique function to consider the unique rows, rather than column elements. The 'stable' argument returns them in the order they were given, rather than sorting them (by default).

The unique function would not automatically eliminate negative values in column 7. I would do that in a separate assignment, before calling unique:

M = randi([-2 2], 10, 7);                               % Create Matrix

M_7nneg = M(M(:,7)>=0, :);                              % Eliminate All Rows With Negative Values In Column #7
[~,idx] = unique(M_7nneg(:,1:5), 'rows', 'stable');     % Unique For Other Criteria
Result = M_7nneg(idx,:)                                 % Desired Result

[Poulomi Ganguli]

Thanks a bunch!!

[Star Strider]

As always, my pleasure!