Opened 10 years ago

Closed 3 years ago

Last modified 2 years ago

#174 closed enhancement (duplicate)

Point Clustering Utility Trigger

Reported by: pramsey Owned by: pramsey
Priority: medium Milestone: PostGIS Fund Me
Component: postgis Version:
Keywords: Cc: brian252

Description

Generating cluster markers for web user interfaces is v. v. common. Function(s) that can run on insert/update/delete that manage a '*_clustered' table would allow people to delegate that problem to the database.

Change History (7)

comment:1 in reply to:  description Changed 10 years ago by pimpaa

Replying to pramsey:

Generating cluster markers for web user interfaces is v. v. common. Function(s) that can run on insert/update/delete that manage a '*_clustered' table would allow people to delegate that problem to the database.

Is this to be used with SnapToGrid?? If so i think i can try something for this, altought i´ll wait and finish the two other tickets...

George

comment:2 Changed 10 years ago by pramsey

No, this is a good deal more involved, potentially. k-means clustering perhaps. gridded systems maybe. it needs some thought, to balance out quality of clustering with cpu load.

comment:3 Changed 10 years ago by pramsey

Milestone: postgis 1.5.0FUTURE

comment:4 Changed 8 years ago by brian252

Cc: brian252 added

I've tried SnapToGrid? in the past and it doesn't look impressive.

I wrote up an implementation of k-means clustering. It's not perfect, but it will work for web-maps. It clustered 22,000 points (tiger.tl_2009_51_cty.pointlm) in about 30 seconds.

The algorithm isn't complicated, but i'm not sure how to set up the mechanics of creating this auxiliary table. It currently runs for n iterations. It would be better to run the clustering until the clusters move less than some delta.

It's hosted here http://brian.derocher.org/?Page=project&Id=104201

comment:5 Changed 7 years ago by strk

An incremental approach is described here: http://web.eecs.utk.edu/~itamar/Papers/ITNG2010.pdf

It would help with maintenance of the '*_clustered' idea

comment:6 Changed 3 years ago by pramsey

Resolution: duplicate
Status: newclosed

Clustering functions are being added, DBScan (#3362) and KMeans (#3465).

comment:7 Changed 2 years ago by robe

Milestone: PostGIS FuturePostGIS Fund Me

Milestone renamed

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