Set the root for a dendrogram

Question

[paolo002]

Hi I have a data which is a binary matrix and I have generated a cluster dendrogram with the hclust function in R. First I normalise the values and then I plot. This is the code:

mat.norm <- t(df / sqrt(2*rowSums(df)))
plot(hclust(dist(mat.norm, "euclidean")))

My data consist of 9 columns and the dendrogram is plotted for all the values of the 9 columns. Does anybody know if it possible to fix one of those column and use it as a root of the dendrogram?