From: Werner Van Belle
Date: March 30 2010 10:31am
Subject: Re: How to deal with 96 Dimensional Points ?
List-Archive: http://lists.mysql.com/mysql/221091
Message-Id: <4BB1D31C.4050805@yellowcouch.org>
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Johan De Meersman wrote:
> Well... a "point" in an n-dimensional space, is a location that has a
> defined value for each of it's n dimensions. If you have a value for
> each of your 96 dimensions, you have a point.
Well, it's fairly simple. If you have two points with 96 values in each.
Point1=3D(x1,...x96) and Point2=3D(y1,...,y96). The distance between thes=
e
two is
d=3Dsqrt( (x_1-y_1)^2 + ... + (x_96-y_96)^2 )
There is no magic in this.
> The mathematics of comparing distances in 96 dimensions is beyond me,
> though :-) I guess a good start would be looking at comparing
> distances in 2 and 3 dimensions (vector math, that is) and trying to
> extrapolate a method from that. Alternatively, hire a mathematician :-p=
Extrapolating from lower dimensions doesn't work too well. In this case
this would mean storing 48 different points and then trying to define a
distance measure based on each individual point. I'm not sure this is
feasable.
In general: KD-trees are quite good tools to deal with such large
dimensional spaces, but I see no possibility to use them in mysql,
Wkr,
>
>
> On Tue, Mar 30, 2010 at 11:39 AM, Werner Van Belle
> > wrote:
>
> Hello,
>
> I have been pondering this for a while, but never really looked dee=
ply
> into the problem.
>
> I have 96 dimensional points and I would like to pose queries such =
as:
> 'give me all points that are within such a radius of this one'.
> The gis
> extensions to mysql might support such type of query. The problem
> is of
> course that points are 2 dimensional and I'm not sure whether I can=
> extend it to more than 3 dimensions ?
>
> Does anybody have an idea about this ?
>
> Wkr,
>
> --
> http://werner.yellowcouch.org/
>
>
>
>
>
> --=20
> Bier met grenadyn
> Is als mosterd by den wyn
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> Hy die't drinkt, is ras een ezel
--=20
http://werner.yellowcouch.org/
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