Calculate the variation of clustering information (Meilă 2007) for each possible pairing of non-trivial splits on n leaves, tabulating the number of pairings with each similarity.

AllSplitPairings(n)

## Arguments

n

Integer specifying the number of leaves in a tree.

## Value

AllSplitPairings() returns a named vector. The name of each element corresponds to a certain variation of information, in bits; the value of each element specifies the number of pairings of non-trivial splits that give rise to that variation of information. Split AB|CD is treated as distinct from CD|AB. If pairing AB|CD=CD|AB is considered equivalent to CD|AB=CD|AB (etc), then values should be divided by four.

## References

Meila M (2007). “Comparing clusterings---an information based distance.” Journal of Multivariate Analysis, 98(5), 873--895. doi:10.1016/j.jmva.2006.11.013 .

Smith MR (2020). “Information theoretic Generalized Robinson-Foulds metrics for comparing phylogenetic trees.” Bioinformatics, 36(20), 5007--5013. doi:10.1093/bioinformatics/btaa614 .

## Examples

AllSplitPairings(6)
#>                0                1 1.33333333333333 1.74837083261218
#>              100              480              360              480
#> 1.83659166810898 1.91829583405449
#>              360              720
# Treat equivalent splits as identical by dividing by four:
AllSplitPairings(6) / 4L
#>                0                1 1.33333333333333 1.74837083261218
#>               25              120               90              120
#> 1.83659166810898 1.91829583405449
#>               90              180