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From Stevo Slavić <ssla...@gmail.com>
Subject Re: Finding best NearestNUserNeighborhood size
Date Wed, 23 Jan 2013 13:11:03 GMT
When evaluating recommender before running evaluator put

RandomUtils.useTestSeed();

to make splitting of data set consistent; don't use it in production, just
for evaluation.
This is all explained more thoroughly in Mahout in Action book.

Kind regards,
Stevo Slavic.


On Wed, Jan 23, 2013 at 2:01 PM, Zia mel <ziad.kamel25@gmail.com> wrote:

> Hi
> I used NearestNUserNeighborhood with RMSE in a user recommender that
> use PearsonCorrelationSimilarity , I found that changing the
> neighborhood size has no clear pattern or effect. Sometimes it
> increase others decrease. While using the neighborhood size with
> precision has a better pattern. Any reason? Another point is that the
> RMSE change for every run since it choose different sample , so would
> running the code for 10 or 20 times and taking the average be a good
> idea or there is better thing to do?
>
> //-- RUN 1
>  2,  0.5523623146152608
>  3,  0.5425283201773704
>  4,  0.669846658662311
>  5,  0.5956616542334392
>  6,  0.6033911039809353
>  7,  0.6135206544496685
>  8,  0.5740444208649034
>  9,  0.642798288443049
>  10,  0.6266535555651472
>
> //-- RUN 2
>  2,  0.5415411343523825
>  3,  0.6784589323396696
>  4,  0.6347069968141124
>  5,  0.6968820296725008
>  6,  0.5953849874479478
>  7,  0.6791828191904128
>  8,  0.6072462830257853
>  9,  0.6461346217476011
>  10,  0.6043919119341171
>
> Thanks !
>

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