意外的聚类错误（围绕中心点进行分区）

Question

我正在使用fpc 包来确定最佳集群数。 pamk() 函数将相异矩阵作为参数，不需要用户指定k。根据documentation：

pamk() 这会调用 pam 和 clara 来围绕 medoids 进行分区 聚类方法（Kaufman 和 Rouseeuw，1990），包括两个 估计聚类数量的不同方法。

但是当我输入两个非常相似的矩阵 - foo 和 bar（数据如下）时，函数在第二个矩阵（条形图）上出错

Error in pam(sdata, k, diss = diss, ...) : 
  Number of clusters 'k' must be in {1,2, .., n-1}; hence n >= 2 

鉴于输入矩阵基本相同，什么可能导致此错误？例如：

foo 有效！

hc <- hclust(as.dist(foo))
plot(hc)
pamk.best <- fpc::pamk(foo)
pamk.best$nc
[1] 2

酒吧没有

hc <- hclust(as.dist(bar))
plot(hc, main = 'bar dendogram')
pamk.best <- fpc::pamk(bar)
Error in pam(sdata, k, diss = diss, ...) : 
  Number of clusters 'k' must be in {1,2, .., n-1}; hence n >= 2

任何建议都会有所帮助！

dput(foo)
structure(c(0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 0, 0, 0, 
0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 
0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 0, 0, 0, 
0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 
0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 9, 9, 9, 
9, 9, 9, 9, 0, 9, 9, 9, 9, 9, 0, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 
0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 0, 0, 0, 
0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 
0, 0, 0, 9, 0, 0, 0, 0, 0, 0, 0, 9, 0, 0, 0, 0, 0, 9, 9, 9, 9, 
9, 9, 9, 9, 0, 9, 9, 9, 9, 9, 0), .Dim = c(14L, 14L), .Dimnames = list(
    c("etc", "etc", "etc", "etc", "etc", "etc", "etc", "similares", 
    "etc", "etc", "etc", "etc", "etc", "similares"), NULL))

dput(bar)
structure(c(0, 6, 6, 6, 6, 6, 0, 0, 0, 0, 6, 0, 0, 0, 0, 6, 0, 
0, 0, 0, 6, 0, 0, 0, 0), .Dim = c(5L, 5L), .Dimnames = list(c("ramírez", 
"similares", "similares", "similares", "similares"), NULL))

Answer 1

bar 具有 n=5 列，因此 max(krange) 必须为 krange；试试：

pamk.best <- fpc::pamk(bar, krange=c(2:(dim(bar)[2]-1)))