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From Sean Owen <>
Subject Re: PlusAnonymousUserDataModel usage?
Date Tue, 21 Sep 2010 08:19:15 GMT
Yes that is what anonymous means here. No not all the DataModels are
mutable. For example FileDataModel is not. It periodically updates from the
files. The idea is that fully reloading and rebuilding can be slow, partly
because it theoretically requires plenty of precomputations down stream to
be re-done. So this is a way to perform the recommendation on some
hypothetical set of preferences that are not actually in existence in the

On Tue, Sep 21, 2010 at 5:35 AM, Lance Norskog <> wrote:

> I conflated the idea of an "anonymous" user and the ability to do this
> query: "suppose I like these 3 movies and hate these 2, what do you
> suggest?" without rebuilding the data structures. Is this what "anonymous"
> means, or is it something more internal?
> The DataModel API lets me add and remove prefs between users and items that
> are already in the data model. I can build a data model with an extra user
> that can be poked at will, and in this way I can lock the recommender, set
> some prefs and make a query, then remove the prefs and release the
> recommender.
> Are all data models obliged to honor this contract of continuous
> mutability? Are they allowed to require a batch data rebuild for any change
> in a user's prefs?
> Sean Owen wrote:
>> Well, you could broadly call all machine learning "analysis and
>> optimization" of a sort! What do you mean, specifically? If you mean
>> you expect this to compute online in real-time rather than off-line,
>> in batch, as the output of some standalone tool -- it is online.
>> You're suppose to query these in realtime. The offline parts of this
>> project are the Hadoop-based ones.
>> There is also no such thing as an "anonymous user" in collaborative
>> filtering per se. It makes no difference whether a user has signed up
>> for an account or not. As long as you can assign some ID to the user,
>> you can inject it into this framework and use any algorithm you want.
>> So in that sense, the whole thing supports anonymous users, and I
>> don't understand the comment.
>> PAUDM is a practical 'hack' to speed up inclusion of such a user. It's
>> useful if not strictly required. It is not as if without that, only
>> users with an account can be used.
>> I'm sorry you're struggling, but it would be more useful to be
>> specific. I've used this particular hack in 2 systems, and helped
>> create 4 others without any particular use of 'anonymous users' and
>> they all most certainly had a point!
>> On Sun, Sep 19, 2010 at 12:21 AM, Lance Norskog<>
>>  wrote:
>>> I don't see the point of a recommender system without the anonymous user
>>> feature. Otherwise it's just a data analysis/optimization tool and there
>>> are
>>> plenty of simpler ways to do that.
>>> Lance

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