MATLAB: Find the number of unique rows and its corresponding index in a matrix

agent based modelalternate functionmatrix rowsunique

Hi there, I need to list the unique rows and its corresponding index in a matrix without the using the unique function. I have been suggested to use the unique function but it seems rather time consuming and I have to run many iterations. Any help will be appreciated. Cheers, Vishal
Data:
v1=[1 2 3 4 5; 5 3 3 2 1; 1 2 4 9 7; 1 2 3 4 5; 5 3 3 2 1]
[a,b,c]=unique(v1,'rows','stable')
The required output which I get from the unique function is:
a =
     1     2     3     4     5
     5     3     3     2     1
     1     2     4     9     7
b =
     1
     2
     3
c =
     1
     2
     3
     1
     2

Best Answer

Perhaps this is more efficient:
v1 = [1 2 3 4 5; 5 3 3 2 1; 1 2 4 9 7; 1 2 3 4 5; 5 3 3 2 1];
vX = v1 * [1, 11, 121, 1331, 14641];
[dummy, b, c] = unique(vX, 'stable');
a  = v1(b, :);
unique() has a remarkable overhead, so you could create a local copy of it and remove the not required checks of the inputs etc.
Related Question