On Mar 2, 2010, at 9:15 PM, Herm Walsh wrote:
I am working with the combinations function (available in the gtools
package). However, rather than store all of the possible
combinations I would like to check each combination to see if it
meets a certain criteria. If it does, I will then store it.
I have looked at the combinations code but am unsure where in the
algorithm I would be able to operate on each combination.
Logical indexing:
> combinations(3,2,letters[1:3])[,1]=="a"
[1] TRUE TRUE FALSE
> combinations(3,2,letters[1:3])[ combinations(3,2,letters[1:3])[,
1]=="a", ]
[,1] [,2]
[1,] "a" "b"
[2,] "a" "c"
--
David Winsemius.
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