R help - May 2009 - Comparing elements of a vector, grouped by values in other vector.

Hi,

I have the following vectors:

    v1 <- rep( LETTERS[ 1:4 ], each = 5)
  v2 <- c( letters[ 1:10 ], letters[ 1:10 ] )

Notice that:
> tapply( B, A, I )
$A
[1] "a" "b" "c" "d" "e"

$B
[1] "f" "g" "h" "i" "j"

$C
[1] "a" "b" "c" "d" "e"

$D
[1] "f" "g" "h" "i" "j"

Here we can see there are two groups of values: *abcde* and *fghij*. This
two groups can have elements in different order so: *abcde* is consider in
the same group as *ebcda*.

I want to obtain the following information:

"There are two groups in vector *v2*, corresponding to levels "A"
and "C" in
vector *v1*"

Any idea?

Thanks

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