Re: Deleting equal rows/columns in matrix

[AlbFrigerio]

OK Jaroslav, here it is the code I implemented. The matrix A was my input, as
you may find in the attached file. I tried to do the same thing with general
matrices of the same size (see the initial commented lines) but every time
unique Octave beated mine ... probably I've been lucky in my example!! By
the way, my function doesn't sort the final matrix as uniques does.

% NR = 500;
% NC = 10;
% A = round(9*rand(NR,NC));
% for i=1:NR
        % if rand<0.5
                % r = 1+(NR-1)*round(rand);
                % A(i,:)=A(r,:);
        % endif
% endfor

A=load("A.txt").A;

t=time;
A_u = unique(A,"rows");
t1=time-t

A_u2 = A;
t=time;
B=A_u2*10.^[size(A_u2,2)-1:-1:0]';
D = repmat(B,1,length(B)) - repmat(B',length(B),1);
[a,b]=find(D==0);
pos=find((a-b)!=0);
        
if ~isempty(pos)
        pos=[a,b](pos,:);
        pos = pos(find(pos(:,1)>pos(:,2)),1);
        val = pos;
        if length(pos)>1
                val = values(pos);
        endif
        pos=val;
endif
A_u2(pos,:)=[];
t2=time-t

t1<t2

http://octave.1599824.n4.nabble.com/file/n3009984/A.txt A.txt 


Jaroslav Hajek-2 wrote:
> 
> 
> Yes, I understand all that. I was just curious whether you can show me
> a case where this approach actually beats Octave's unique by a
> significant margin. I'm still interested, but please give the *exact*
> code including the time measurements, I can't guess what you actually
> did.
> _______________________________________________
> Help-octave mailing list
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> 

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