On May 11, 2010, at 4:54 PM, Ista Zahn wrote:
On Tuesday 11 May 2010 4:27:01 pm David Winsemius wrote:
On May 11, 2010, at 1:45 PM, chen jia wrote:
Hi there,
I am looking for a function that takes a vector as input and
generates
all pair wise combination of the elements of the input vector.
?combn
For example, the input vector is c(1,2,3,4). The output vector is
c(1
and 2, 1 and 3, 1 and 4, 2 and 3, 2 and 4, 3 and 4).
That's not a vector.
True, although it is possible the OP wanted paste(combn(1:4, 2)[1,],
"and",
combn(1:4, 2)[2,])
True enough, but then it would look like c("1 and 2", "1 and 3", ...
etc. Or he could have wanted a matrix, or he could have wanted:
expand.grid(c(1,2,3,4),c(1,2,3,4))
or... any one of a number of things. If, as he said, he was already
successful in creating whatever it was that he wanted, then he
_should_ have offered a valid R object, so we wouldn't need to guess.
-Ista
The
representation here is generic.
Whatever that meant.
I can use a for loop to do it, but it gets slow when the number of
elements of the input vector is large.
Best,
Jia
David Winsemius, MD
West Hartford, CT
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