[R] silhouette plot for kmeans result

[Martin Maechler]

>>>>> "LS" == Linda Smith <lsmithingm at gmail.com>
>>>>>     on Mon, 3 Mar 2008 00:57:49 -0800 writes:

    LS> Dear All,
    LS> Is there any existing code for plotting silhouette for kmeans clustering
    LS> results?

Yes.  Have you tried at all?

Anyway, here's some commented example code
(with a largish data) :

library(cluster)
data(xclara)

plot(xclara) # 3000 observations; a bit large for dissimilarity plotting

km <- kmeans(xclara,3)

## Now the silhouette concept builds on dissimilarities
## e.g.
dissE <- daisy(xclara) #-> large (!)  3000 x 3000 / 2
sk <- silhouette(km$cl, dissE)
plot(sk)

## but kmeans is rather equivalent to work with  {D_ij}^2,
## hence this better corresponds:
dE2 <- dissE^2
sk2 <- silhouette(km$cl, dE2)
plot(sk2)



    LS> Many thanks!
    LS> Linda

you're welcome.

Martin Maechler, ETH Zurich