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From Marcus Herou <marcus.he...@tailsweep.com>
Subject Re: Sort by value
Date Thu, 09 Jul 2009 17:08:45 GMT
Fair enough, thanks for the input!

Cheers

/Marcus


On Thu, Jul 9, 2009 at 7:03 PM, Miles Osborne <miles@inf.ed.ac.uk> wrote:

> if you have <key,value> pairs, then have your mapper emit
>
> <value,<key,value>>
>
> this will result in your data being resorted by the value
>
> Miles
>
> 2009/7/9 Marcus Herou <marcus.herou@tailsweep.com>
>
> > Really ? WIll that work ?
> >
> > input something like this
> >
> > tag
> > tag2
> > tag
> > tag2
> > tag3
> > ...
> > produces output
> >
> > tag 2
> > tag2 2
> > tag3 1
> > ....
> >
> > Swapping key/value will then map all 2's to what ?
> >
> >
> >
> > On Thu, Jul 9, 2009 at 4:53 PM, jason hadoop <jason.hadoop@gmail.com>
> > wrote:
> >
> > > The simplest way is to swap the key and value in your mapper's output,
> > then
> > > swap them back afterward.
> > >
> > > On Thu, Jul 9, 2009 at 7:52 AM, Marcus Herou <
> marcus.herou@tailsweep.com
> > > >wrote:
> > >
> > > > Hi many times I want to sort by value instead of key.
> > > >
> > > > For instance when counting the top used tags in blog posts or the ten
> > > most
> > > > visited pages on a certain site and so on.
> > > >
> > > > Wondering if that is even possible with hadopp or if I need to
> process
> > > the
> > > > file outside of hadoop.
> > > >
> > > > Cheers
> > > >
> > > > /Marcus
> > > >
> > > > --
> > > > Marcus Herou CTO and co-founder Tailsweep AB
> > > > +46702561312
> > > > marcus.herou@tailsweep.com
> > > > http://www.tailsweep.com/
> > > >
> > >
> > >
> > >
> > > --
> > > Pro Hadoop, a book to guide you from beginner to hadoop mastery,
> > > http://www.amazon.com/dp/1430219424?tag=jewlerymall
> > > www.prohadoopbook.com a community for Hadoop Professionals
> > >
> >
> >
> >
> > --
> > Marcus Herou CTO and co-founder Tailsweep AB
> > +46702561312
> > marcus.herou@tailsweep.com
> > http://www.tailsweep.com/
> >
>
>
>
> --
> The University of Edinburgh is a charitable body, registered in Scotland,
> with registration number SC005336.
>



-- 
Marcus Herou CTO and co-founder Tailsweep AB
+46702561312
marcus.herou@tailsweep.com
http://www.tailsweep.com/

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