[R] Rendering Dendrograms

[Thomas Petzoldt]

Hi Mark,

similar questions were at least two times during the last weeks, see

http://tolstoy.newcastle.edu.au/R/e5/help/08/11/6722.html

http://tolstoy.newcastle.edu.au/R/e5/help/08/11/6736.html

or

http://tolstoy.newcastle.edu.au/R/e5/help/08/11/7790.html

or search the archives yourself:

http://tolstoy.newcastle.edu.au/R/

search for "cluster graph" or "plot.hclust"


Thomas P.


Mark Cook wrote:
> 
> 
> 
> Hello all
> I've been using the hclust and as.dendrogram objects for hierarchical
> clustering. The problem I have is that my sample set is now so large (circa
> 500 points) that it isn't possible to view the leaf nodes.
> 
> I'd like to be able to zoom in on specific areas of the graph by 
> selecting a
> region with the mouse.  I've deduced from trial and error that the xlim and
> ylim parameters don't work with these plots and the only method I've had 
> any
> success with is to cut the tree at a specific point and display the lower
> region.  However, the cut function returns a list of all subtrees below the
> specified height and I have no way of selecting a particular subtree (that
> is, cutting on the x-axis).
> 
> The identify and rect.hclust functions seem to do this OK  and  in fact 
> these
> partially solve my problem but I want to use getGraphicsEvent() if possible
> since this also allows interaction with the keyboard (so that I can use the
> backspace key for example to return to the previous plot). I'm fairly 
> new to
> R so may be wrong but it appears that the plots are single threaded and can
> respond to either a set of graphics events or an identify loop but not 
> both)
> 
> It has been suggested that I look at  Graphviz since this has more
> comprehensive mapping facilities. Is this likely to help? Is there for
> example a method for converting an R hclust object to an Graphviz ICLUST or
> some alternative method for describing an hclust in the Graphviz .DOT
> notation?
> 
> Or can anybody suggest an alternative approach ??
> 
> Regards
> 
> Mark
> 
> 
>>
>>
>>
> 
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