[R] Combinations of true/false values where one pair is mutually exclusive

[S Ellison]

> Given that clarification, I'd just generate the full set and remove
> the ones you aren't interested in, as in:
I'd agree; that is probably the most efficient thing to do with only half a dozen binary variables and a single condition.

A way of going about it for a more complex case might be to generate a single dummy variable encoding the special case combinations in the expand.grid step, and then decode that. For example (using this case):

allowed.EF <- data.frame(E=c("pass", "pass", "fail"), F=c("pass", "fail", "pass" ))

AtoEF <- expand.grid(A=c("pass", "fail"),B=c("pass", "fail"), C=c("pass", "fail"), D=c("pass", "fail"), EF=1:3 )

AtoF <- cbind(AtoEF[1:4], allowed.EF[AtoEF$EF,])

#Which gives the same combinations as Sarah's complete/subset method, albeit in a different order and with silly row names.




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