[R] Classification tree data structure

[Prof Brian Ripley]

On Tue, 18 Oct 2005, Hades wrote:

> Hi there,
>
> I am growing classification trees using the 'tree' package add-on to R.
>
> I would like to convert the 'R' output to the SAS format used by Salford Systems' commercial CART software in order to interface with some
> other software.
>
> My question is:

> How can I parse the R tree data structure in order to infer the tree 
> structure?  The 'tree' class has a member '$frame' which gives the 
> splits at each node, but as far as I can see does not specify the 
> daughter nodes.  Is this information accessible through the interface to 
> class 'tree' or do I need to dive into the C code?

The daughter nodes of n are 2n and 2n+1.  The print method, print.tree, is 
written entirely in R and shows you how to parse the tree (and you can see 
the pattern of the numbers from its result).

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595