[R] Matrix manipulation

[Patrick Connolly]

I have a square matrix wherein a '*' indicates an HSD between the
levels indicated by row name and column name.  The '.' is simply
marking the diagonal.  A blank indicates the same group


  A B C D E F G H I J K L M N
A .                          
B   .                        
C * * .                      
D * *   .                    
E * * *   .                  
F * * *     .                
G * * *       .              
H * * *         .            
I * * * * * * *   .          
J * * * * * * *     .        
K * * * * * * * *     .      
L * * * * * * * * * *   .    
M * * * * * * * * * *     .  
N * * * * * * * * * * * *   .


I'm having trouble devising a method that ends up with groups of the
14 levels, such as this:

A a
B a
C b
D bc
E c
F c
G c
H cd
I d
J d
K d
L de
M de
N e

It's not important to make it vectorized, since the matrix is small,
but I could be doing this often enough to not want to do it by hand.

Suggestions welcome.

Thanks

-- 
Patrick Connolly
HortResearch
Mt Albert
Auckland
New Zealand 
Ph: +64-9 815 4200 x 7188
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