Efficient application of unique and strcat functions

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Maria
Maria 2014-8-10
编辑： per isakson 2014-8-23
I use the following code on several occasions to keep only the rows with the condition that X elements don't repeat:
[~, ind,~] = unique(strcat(a(:,2)a(:, 6)));
a = a(ind,:);
In this case I keep the rows that have different combinations of the elements of column 2 and 6.
I use the functions unique and strcat because they work for cell type variables with both strings and numbers . The problem is that this code is not efficent and takes a lot of time to run. I was wondering if someone had a better solution. Thank you

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Matt J
Matt J 2014-8-10
编辑：per isakson 2014-8-23
Looks like you need the 'rows' flag in your call to unique. Also, it might help to avoid requesting additional output arguments that you don't need.
a = unique(strcat(a(:,2),a(:,6)),'rows');
Note that the use of ~ output arguments isn't the same as requesting fewer outputs. The ~ outputs will still be computed. They just won't be stored anywhere.

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