[R] A particular shuffling on a vector
Emmanuel Levy
emmanuel.levy at gmail.com
Fri Apr 20 03:03:01 CEST 2007
Hello,
I was wondering if anyone can think of a straightforward way (without
loops) to do the following shuffling:
Let's imagine a vector:
c(1,1,1,2,2,3,3,3)
I would like to derive shuffled vectors __where the same digits are
never separated__, although they can be at both ends (periodicity).
So the following shuffled vectors are possible:
c(2,2,1,1,1,3,3,3)
c(2,1,1,1,3,3,3,2)
c(3,3,3,1,1,1,2,2)
c(3,1,1,1,2,2,3,3)
etc ...
I should mention that there can be any number of different numbers,
and any number of repetition of each number.
So the vectors I have to deal with could look like
c(1,1,2,3,4,5,6,6,6,6,6,6,6,6,7,8) for example
Since I have to derive many shuffled versions for each vector, I am
looking for an efficient way of doing it. Can you think of a way
without nested loops?
Many thanks for your help,
Best,
Emmanuel
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