SQL like question.

[Levente Torok]

Hi All,

Last time Jaroslav helped me a lot with a little trick but this time I am a little bit jammed.

I would like to get solved a simple thing again and I cannot find a fast solution to it.

I have a matrix as
m = [
1 2; 
1 1; 
2 3; 
2 4 ];

I would like to make a unique of its first column but I would like to have the minimum of second column nearby.
So it would look like:
[ 1 1; 
  2 3 ]

This is something like SELECT first_col, min(second_col) FROM m GROUP BY first_col;

If I can be sure that the second nargout of unique() always points always to the last index of the same 
selector item then the solution would be something like:

m = sort( m, 'descend' );
[u,i,j] = unique( m(:,1) );
m(i,:)

but 
1) can I be sure about it?
2) what if I would want to make aggregate functions such as avg()  or var()

Thanks a lot,

Levente

-- 
Blogger of http://fapuma.blogspot.com