[R] Intransitive DAG

[Thomas S. Dye]

David Winsemius <dwinsemius at comcast.net> writes:

> On Jul 11, 2011, at 3:28 PM, Thomas S. Dye wrote:
>
>> Aloha all,
>>
>> I have an adjacency matrix for an acyclic digraph that contains
>> transitive relations, e.g. (u,v), (v,w), (u,w).  I want a DAG with
>> only
>> intransitive relations.  Can someone point me to an R function that
>> will
>> take my adjacency matrix and give me back one with only intransitive
>> relations?  In the example, I'd like to get rid of (u,w) and keep
>> (u,v)
>> and (v,w).
>
> I'm needing to guess at what sort of code you are using but assuming
> this is a square matrix:
>
> require(ggm)
> dag <- DAG(y ~ x, x ~ z, u~z)
>> which(dag != t(dag), arr.ind=TRUE)
>   row col
> x   2   1
> y   1   2
> z   3   2
> x   2   3
> u   4   3
> z   3   4
>

Aloha David,

Thanks for this suggestion.  I don't think it does what I want.  Sorry
if I wasn't precise.  The graph theory language is new to me.

What I'm looking for is a function that gets rid of transitive
relations, like so:

tdye> dag <- DAG(v ~ u, w ~ v, w ~ u)
tdye> dag
  v u w
v 0 0 1
u 1 0 1
w 0 0 0
tdye> dag[2,3] <- 0
tdye> dag
  v u w
v 0 0 1
u 1 0 0
w 0 0 0

All the best,
Tom

>> All the best,
>> Tom
>> --
>> Thomas S. Dye
>> http://www.tsdye.com
>>
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>
> David Winsemius, MD
> West Hartford, CT
>

-- 
Thomas S. Dye
http://www.tsdye.com