Hi- First off, you can use the PDL on-line documentation to find relevant commands to try:
pdldoc -a maximum or pdl> apropos maximum in the pdl2 or perldl shells includes the following items: maximum Project via maximum to N-1 dimensions maximum_ind Like maximum but returns the index rather than the value maximum_n_ind Returns the index of `m' maximum elements where maximum_n_ind is what you are looking for. Here is a sample pdl2 session showing the calculation. You can use the PDL shells and the online documentation to understand fully how it works: pdl> floor(random(10,10)*10) > pdl> p $m > [ > [4 7 5 0 6 7 8 4 6 7] > [0 7 0 2 5 3 0 4 6 6] > [5 4 3 6 9 5 8 4 4 1] > [9 6 7 7 4 1 4 2 0 8] > [5 1 3 3 7 7 1 2 8 5] > [2 0 8 7 3 1 5 7 7 6] > [5 9 6 2 7 2 6 7 0 2] > [6 3 1 1 8 2 1 9 9 9] > [6 7 9 3 5 2 2 5 9 3] > [4 5 0 4 7 9 3 3 1 6] > ] > > pdl> $top5 = zeros indx, 5; # size of $top5 determines n > pdl> $m->flat->maximum_n_ind($top5) # get top 5 element indexes > pdl> p pdl($m->one2nd($top5)) # convert linear to ND index > [ > [4 0 1 7 8] > [2 3 6 7 7] > ] > > > Hope this helps, Chris On Fri, Oct 17, 2014 at 11:54 AM, Ronak Agrawal <[email protected]> wrote: > First I would Thank You for your constant help...it has helped me a lot in > improving my skills > ------- > > I have generated a Hankel Matrix by the following operation > > // $a is a svd and therby this operation will always form Hankel Matrix > $matrix = $a x transpose($a); > > [image: [a b c d e; b c d e f; c d e f g; d e f g h; e f g h i].] > > I need to find the top K minimum elements ( 2D) with their 2 Dimesional > indices .. > Can you suggest me some good approach for this > > I though to do following but it is not optimized > Converting the Lower triangular Matrix as Bad Values or 0 > Then Finding the mimimum row_wise and column_wise using minimum function > > Thanks > > > > > > _______________________________________________ > Perldl mailing list > [email protected] > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl > >
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