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> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enig5E8BDD27F50E7CDC58325575" --------------enig5E8BDD27F50E7CDC58325575 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable 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 > Sy die't drinkt, is eene kwezel > Hy die't drinkt, is ras een ezel --=20 http://werner.yellowcouch.org/ --------------enig5E8BDD27F50E7CDC58325575 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iEYEARECAAYFAkux0xwACgkQ2TDF0fTmy3UWVACfREgavKIIIkPsGCt4umqKFzdt x3IAn3LZ6BnEjiAvkm6t9jt1Ge069xVK =jb5a -----END PGP SIGNATURE----- --------------enig5E8BDD27F50E7CDC58325575--