15 jul 2008 kl. 10.20 skrev Sascha Fahl:
There is a big difference between GeoSearch and GeoSort. GeoSearch
means you are looking for data within a certain range. To implement
this index structures like R-Trees help, because they make it a lot
easier to think in "boxes". GeoSort is just to sort the data in
relation to a given point in a 2D environment. So you always have to
compute the distance from the given point to the locations of the
documents. I think this is the only possibly approach?
What I really tried to say is that if you are looking at improving a
lat/long related solution you'll probably find more expertize on the
user lists of the projects I mentioned.
They too sort their results by distance. My guess is that they make
use of the "boxes" there too. If, then I don't know if you can use
their API as any other Lucene index. If not, well then you've probably
got a really nice GeoSort to plug in to your application right here
and now.
LocalLucene/trunk/README:
//Create a distance sort using the radial filter (distance
calculations are done
// in the radial filter, so use the output of that to drive the sort)
DistanceSortSource dsort = new DistanceSortSource(filter);
Sort sort = new Sort(new SortField("foo", dsort));
karl
Am 15.07.2008 um 10:05 schrieb Karl Wettin:
15 jul 2008 kl. 09.50 skrev Sascha Fahl:
I read the chapter about custom sort methods and hacked around
with the GeoSort. Are there ways to improve the algorithm?
Espacially calculating the distance for ALL documents in the index
is a bad idea because only the distance for hitted documents are
of interest. That could save lots of time because the number of
hits compared to all documents in an index usually is pretty small.
GeoLucene and LocalLucene are both branches of Lucene hacked to
handle geo-positioning problems. You might want to take a look at
them if that is features you are looking for. I suppose the code in
the book is mearly an example to show how to implement a custom
sort, but I didn't read it so I'm just guessing here.
karl
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Sascha Fahl
Softwareenticklung
evenity GmbH
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