[R] union of list objects if objects intersect

[Bert Gunter]

Your specification is a unclear (to me anyway): What do you want to
return if the intersection is empty? What if intersect(ja[[i]],
ja[[i+1]]) is empty for all i? What if  length(intersect( ja[[i]],
ja[[i+1]] )) ==0 but intersect(ja[[i]],ja[[i+2]]) is nonempty?  Your
example isn't -- you did not specify what the return should be on your
list.

Note also that your example test  is wrong: the length of the
intersection must =0 not the intersection.

-- Bert



On Sat, Nov 9, 2013 at 12:45 PM, Hermann Norpois <hnorpois at gmail.com> wrote:
> Hello,
>
> I have a list called ja and I wish to unify list objects if there is some
> overlap.
> For instance something like
>
> if (length (intersect (ja[[1]], ja[[2]]) !=0) { union (ja[[1]], ja[[2]] }
>
> but of course it should work cumulatively (for larger data sets).
>
> Could you please give me a hint.
>
> Thanks
> Hermann
>
>> ja
> $A
> [1] "A" "B" "F" "G" "H"
>
> $B
> [1] "B" "F" "I"
>
> $C
> [1] "C" "F" "I" "K"
>
> $D
> [1] "D" "L" "M" "N"
>
> $L
> [1] "L" "O" "P"
>
>
> dput (ja)
> structure(list(A = c("A", "B", "F", "G", "H"), B = c("B", "F",
> "I"), C = c("C", "F", "I", "K"), D = c("D", "L", "M", "N"), L = c("L",
> "O", "P")), .Names = c("A", "B", "C", "D", "L"))
>
>         [[alternative HTML version deleted]]
>
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-- 

Bert Gunter
Genentech Nonclinical Biostatistics

(650) 467-7374