Marie Sivertsen wrote:
Dear list,
I have a vector of elements which I want to combined each with each, but
none with itself. For example,
v <- c("a", "b", "c")
and I need a function 'combine' such that
combine(v)
[[1]]
[1] "a" "b"
[[2]]
[1] "a" "b"
[[3]]
[1] "b" "c"
I am not very interested in the orders of the output items for now, and the
form can be something differs from list, like matrix or data frame. I know
of 'expand.grid', but it will combine each item with each item including
itself, so not what I wants.
Could you help me please. Thank you.
Mvh.,
Marie
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I guess you actually want,
[[1]]
[1] "a" "b"
[[2]]
[1] "a" "c" # not "a" "b" again
[[3]]
[1] "b" "c"
if so, try
?combn
> combn(v,2)
[,1] [,2] [,3]
[1,] "a" "a" "b"
[2,] "b" "c" "c"
HTH,
baptiste
--
_____________________________
Baptiste Auguié
School of Physics
University of Exeter
Stocker Road,
Exeter, Devon,
EX4 4QL, UK
Phone: +44 1392 264187
http://newton.ex.ac.uk/research/emag
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and provide commented, minimal, self-contained, reproducible code.
