Anthony Some of the best clustering techinques have been created and high documented by Martin Pearman
http://googlemapsapi.martinpearman.co.uk/home.php Clustermarker http://googlemapsapi.martinpearman.co.uk/articles.php?cat_id=1 Note: Latest News Martin is working on a new version (noted on 4th October 2009) "I am working on a new version of ClusterMarker. The new version is (i hope!) going to be faster and more efficient. Lots of ideas and feedback from the forum have inspired the new version and i'm sure it will be a major update. I plan to have a working alpha or even beta version available within a week (or is that too optimistic? lol). Well a week later and i've been too busy working to make any progress on the new version. But watch this space - i'm keen to get the new version complete and online as soon as possible. Martin Pearman." Mapperz http://mapperz.blogspot.com/ On Oct 15, 4:54 pm, Anthony <[email protected]> wrote: > I've been looking into clustering algorithms, as some of my projects > will use them. It seems all of the ones I've looked at use similar > math, which leads to what I would call "cartographic" issues. I'm sure > people know of the issues (see examples below), and they are somewhat > inherent to the algorithms, particularly if performance is high > priority. However, I'm wondering if anyone knows of any other > approaches that alleviate these issues. Or more broadly, are there any > good web pages that examine and compare the pros and cons of various > approaches? > > Here are some of the issues. These apply to the distance-based > algorithms -- I'm not considering grid-based ones. Mostly the issues > are the result of using marker locations for the cluster location and > the fact that markers are considered in order one-by-one. Note that > the issues do not mean that clustering doesn't work, just that the > results are not the best cartographically. > > For the examples below X is the clustering distance and E is some > small epsilon distance. > > Ex. #1: Different order produces different clusters > Consider the points: (1) <-- X-E --> (2) <-- X-E --> (3) > Which cluster as: (1&2) <-- 2X-2E --> (3) > Reordering to: (2) <-- X-E --> (1) <-- X-E --> (3) > Clusters as: (1&2&3) > > Ex. #2: Same issue, but a less trivial case than above > Points: (1) <------ X-E ------> (2) <-- 4E --> (3) <------ X-E ------> > (4) > Clusters: (1&2) <-------- 2X+2E --------> (3&4) > Ideal(?): (1) <------ X+E ------> (2&3) <------ X+E ------> (4) > > (Hopefully the formatting is okay.) --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Google Maps API" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/google-maps-api?hl=en -~----------~----~----~----~------~----~------~--~---
