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From: Sean on 16 Jul 2010 16:13
"Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message <i1qe3f$ouh$1(a)fred.mathworks.com>...
> Almost the same solution, but for large size:
>
> a=ceil(4000*rand(1e5,5));
>
> full(sum( sparse(mod((0:numel(a)-1)',size(a,1))+1, a(:), 1) > 0,1))
>
> % Bruno

That wins:
%Elapsed time is 0.199475 seconds.
From: us on 16 Jul 2010 17:05
"Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message <i1qe3f$ouh$1(a)fred.mathworks.com>...
> Almost the same solution, but for large size:
>
> a=ceil(4000*rand(1e5,5));
>
> full(sum( sparse(mod((0:numel(a)-1)',size(a,1))+1, a(:), 1) > 0,1))
>
> % Bruno

but with a lot of unnecessary data...

a=[ceil(10*rand(1e5,5))+100000;ceil(10*rand(1e5,5))+200000];
r=full(sum( sparse(mod((0:numel(a)-1)',size(a,1))+1,a(:),1)>0,1));
whos r;
%{
Name Size Bytes Class Attributes
r 1x200010 1600080 double
%}
% while
au=unique(a);
size(au)
% ans = 20 1

just a pedestrian thought...
us
From: Bruno Luong on 16 Jul 2010 17:33
"us " <us(a)neurol.unizh.ch> wrote in message <i1qhi5$2jl$1(a)fred.mathworks.com>...
> "Bruno Luong" <b.luong(a)fogale.findmycountry> wrote in message <i1qe3f$ouh$1(a)fred.mathworks.com>...
> > Almost the same solution, but for large size:
> >
> > a=ceil(4000*rand(1e5,5));
> >
> > full(sum( sparse(mod((0:numel(a)-1)',size(a,1))+1, a(:), 1) > 0,1))
> >
> > % Bruno
>
> but with a lot of unnecessary data...
>
> a=[ceil(10*rand(1e5,5))+100000;ceil(10*rand(1e5,5))+200000];
> r=full(sum( sparse(mod((0:numel(a)-1)',size(a,1))+1,a(:),1)>0,1));
> whos r;
> %{
> Name Size Bytes Class Attributes
> r 1x200010 1600080 double
> %}
> % while
> au=unique(a);
> size(au)
> % ans = 20 1
>
> just a pedestrian thought...
> us

I assume OP have posted this thread without random coincidence:
http://www.mathworks.com/matlabcentral/newsreader/view_thread/287043

Bruno
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