[R] Test of Presence Matrix HOWTO?
Johannes Graumann
johannes_graumann at web.de
Mon Feb 26 16:25:21 CET 2007
Hello,
Imagine 3 lists like so:
> a <- list("A","B","C","D")
> b <- list("A","B","E","F")
> c <- list("A","C","E","G")
What I need (vennDiagram) is a matrix characterizing with 1 or 0 whether any
given member is present or not like so:
x1 x2 x3
[1,] 1 1 1
[2,] 1 1 0
[3,] 1 0 1
[4,] 1 0 0
[5,] 0 1 1
[6,] 0 1 0
[7,] 0 0 1
(where the rows represent "A"-"G" and the columns a-c, respectively).
> table(c(a,b,c))
will give me a quick answer for the "1 1 1" case, but how to deal with the
other cases efficiently without looping over each string and looking for
membership %in% each list?
Thanks for enlightening the learning,
Joh
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