On Thu, Nov 12, 2009 at 10:01 AM, Christopher Barker <chris.bar...@noaa.gov>wrote:
> Peter Schmidtke wrote: > > On Tue, 10 Nov 2009 16:07:32 -0800, Christopher Barker > > <chris.bar...@noaa.gov> wrote: > > >> I have a bunch of points in 2-d space, and I need to find out which > >> pairs of points are within a certain distance of one-another (regular > >> old Euclidean norm). > > > > How big is your set of points? > > Could be 100s of thousands, maybe ever millions. That's why O(N^2) is > not good. > > Another question is density. Are the points randomly scattered or do they cluster? The order N^2 part can be taken care of if you can easily eliminate a large fraction of the points, say by gridding the 2D part. Chuck
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