>>>>> On Fri, 26 Oct 2007 07:19:45 -0700 (PDT), >>>>> Tim Smith (TS) wrote: > Hi Friedrich, > Thanks for the response! > I have tried the following: > --------------------------------------------------------- > nums <- sample(1:300,70) > x <- matrix(nums,10,7) > mygroups <- c(1,3,4) # i.e. I would like these 3 rows in 'x' to > cluster together The group vector needs to be a factor or integer vector with the same length as x has rows, otherwise it will be recycled as in many other functions. See below for a working example. In the usual setting the grouping would be a factor variable in your data frame. > myfam <- kccaFamily("kmeans", groupFun = "minSumClusters") > clres <- kcca(x, k=3, myfam, group=mygroups) > -------------------------------------------------------- > I get the following result: >> clres > kcca object of family 'kmeans' > call: > kcca(x = x, k = 3, family = myfam, group = mygroups) > cluster sizes: > 1 2 > 3 7 > I have two questions: > i) How do I get the details of the clusters (i.e which points/rows > are in which cluster)? cluster(clres) > ii) If k=3, then shouldn't there be 3 clusters? If a cluster gets empty during the iterations it is removed, so you can end up with less clusters than you asked for. For grouped clustering this happens more often than for regular kmeans because of the re-assignement of group members. A working example: set.seed(12) ## same as above nums <- sample(1:300,70) x <- matrix(nums,10,7) ## Rows 1, 3 and 4 are in group 1, all other groups contain ## only one observation mygroups <- c(1,2,1,1,3,4,5,6,7,8) myfam <- kccaFamily("kmeans", groupFun = "minSumClusters") clres <- kcca(x, k=3, myfam, group=mygroups) R> clres kcca object of family ?kmeans? call: kcca(x = x, k = 3, family = myfam, group = mygroups) cluster sizes: 1 2 3 3 5 2 R> table(cluster(clres),mygroups) mygroups 1 2 3 4 5 6 7 8 1 3 0 0 0 0 0 0 0 2 0 1 0 1 1 1 1 0 3 0 0 1 0 0 0 0 1 and all members of group 1 end up in cluster 1 (note: need not be cluster 1) hth, fritz -- ---------------------------------------------------------------------- - Prof. Dr. Friedrich Leisch Institut f?r Statistik Tel: (+49 89) 2180 3165 Ludwig-Maximilians-Universit?t Fax: (+49 89) 2180 5308 Ludwigstra?e 33 D-80539 M?nchen http://www.stat.uni- muenchen.de/~leisch