Home | About | Sematext search-lucene.com search-hadoop.com
 Search Hadoop and all its subprojects:

Switch to Threaded View
MapReduce >> mail # user >> How would you translate this into MapReduce?


Copy link to this message
-
Re: How would you translate this into MapReduce?
Assume Joe visits Washington, London, Paris and Moscow

You start with records like
Joe:Washington:20-Jan-2011
Joe:London:14-Feb2011
Joe:Paris :9-Mar-2011

You want
Joe: Washington, London, Paris and Moscow

For the next step the person is irrelevant
you want
Washington:  London:1, Paris:1 ,Moscow:1
 London: , Paris:1  Moscow:1
 Paris:   Moscow:1
The first say after a visit to Washington there was one visit to London, one
to Paris and one to Moscow
This can be combined with the one from Joe
Now suppose Bill visits London and Moscow
So he generates
London:    Moscow:1

This can be combined with the one from Joe saying  London: , Paris:1 and
Moscow:1
 to give

 London: , Paris:1 and Moscow:2

Now suppose Sue visits London and  Riga and Paris
So she generates
London: , Paris:1,Riga 1

This can be combined with  London: , Paris:1 and Moscow:2 to give

London: , Paris:2 and Moscow:2,Riga 1

Note I can keep places in alphabetical order in the result

On Tue, Jul 19, 2011 at 9:53 AM, Em <[EMAIL PROTECTED]> wrote:

> Hi Steven,
>
> thanks for your response! For the ease of use we can make those
> assumptions you made - maybe this makes it much easier to help. Those
> little extras are something for after solving the "easy" version of the
> task. :)
>
> What do you mean with the following?
>
> > The second job takes Person : list of places and return for each place
> > in the list consructs
> > place : 1 | place after P : 1 | next place : 1 ...
>
> You mean something like that?
>
> Washington DC:1
> New York after Washington DC:1
> Miami after New York:1
>
> I do not see the benefit for the result I like to get?
>
> The end-result should be something like that:
> Washington DC => New York, Miami, Los Angeles
> New York => Chicago, Seattle, San Francisco
>
> The point is, that one can see that persons that visited Washington DC
> are likely to visit New York as the next place, Miami as the second and
> L.A. as the third.
> However, if I choose New York as my starting point, I can see that
> persons that start their journey in New York (and maybe weren't in DC
> before) are likely to visit Chicago, Seattle and San Francisco. Maybe
> Los Angeles comes at the 10th position.
>
> Regards,
> Em
>

--
Steven M. Lewis PhD
4221 105th Ave NE
Kirkland, WA 98033
206-384-1340 (cell)
Skype lordjoe_com