[Rd] "cophenetic" function for objects of class "dendrogram"

[Alberto Fernández Sabater]

Hello,


I have been using the "cophenetic" function for objects of class "dendrogram" and I have realised that it gives different results when it is used with objects of class "hclust". For instance, running the first example in the help file of the "cophenetic" function,


d1 <- dist(USArrests)

hc <- hclust(d1, "ave")

d2 <- cophenetic(hc)

cor(d1, d2)  # 0.7659


the result given is different to the one obtained using an object of class "dendrogram",


dendro <- as.dendrogram(hc)

d3 <- cophenetic(dendro)

cor(d1, d3)  # 0.0151


I think that it would be desirable to obtain the same result with all the "cophenetic" methods, irrespectively of the class of the object used. If this is not possible, users could be warned in the help file.


Thanks,

Alberto Fernandez


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