Thanks Mario! (Oppure grazie Mario?) - Can those silhouette coefficients be used for distances between sets or only for distances point to set?
- Where did you get the other post you attached? It did not come up when I searched the mailing list! Best, On Tuesday 01 December 2009 10:31:47 Mario Valle wrote: > silhouette coefficients? > It measure for each point how similar is to its cluster other points and > how dissimilar from the points of other clusters. > > P.N. Tam, M. Steinbach, V. Kumar, Introduction to data mining, > Addison-Wesley, 2006 page 541 > > Hope it helps. > mario > > Charlotte Maia wrote: > > Well, here's another naive post from me (hopefully better than the last > > one). > > > > Firstly I'm not sure computing euclidean distance is that simple. I > > would assume temperatures and precipitation would need to be > > standardised in some way. > > > > I think the notion of how far away something is, and how distinct > > location wise something is, are quite different, so maybe two > > measures? > > > > For distance per se, I think your first idea is the best. > > Plus simple is always good... > > > > For distinctness, given one one of two sets, for each point, you could > > just compute the closest point to it. If the closest point is a member > > of the same set, we will call that a + point, if the closest point is > > a member of the other set, we will call it a - point. In principle the > > measure of distinctness would be the sum of the +'s, however there > > might need to be some scaling to take into account the number of > > points in each set. > > > > There are also a lot of fancy things out there, so someone will > > probably come up with a much fancier (and possibly better) idea than > > this. > > > > Well, that's just my rant, before I go to bed. > > > > > > kind regards > -- Corrado Topi Global Climate Change & Biodiversity Indicators Area 18,Department of Biology University of York, York, YO10 5YW, UK Phone: + 44 (0) 1904 328645, E-mail: ct...@york.ac.uk ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.