Hi all,

I have got a 8000*200 gene expression matrix. I am clustering rows and
columns with hclust.

I want to plot something like generated by 'heatmap' which means an heatmap
with corresponding array and gene trees. So, the fact is that the gene tree
should be horizontal.

With 'plot' function applied to an hclust object, the dendrogram is always
vertical. But plotting the tree is really fast.

To plot the gene tree horizontal, I saw that coercing the hclust object with
as.dendrogram allows one to use the option horiz=TRUE in 'plot'. That's
pretty true but plotting the dendrogram for 8000 genes requires then an
infinity of time. I see each branch of the tree be slowly drawn one by one.

Why this difference in calculation time ?
And is there a way to plot a horizontal tree as quick as
'plot(hclust_object,...)' does ?


best regards,

tony

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