Calculate the entropy, joint entropy, entropy distance and information content of two splits, treating each split as a division of n leaves into two groups. Further details are available in a vignette, MacKay (2003) and Meilă (2007).

SplitEntropy(split1, split2 = split1)


split1, split2

Logical vectors listing leaves in a consistent order, identifying each leaf as a member of the ingroup (TRUE) or outgroup (FALSE) of the split in question.


A numeric vector listing, in bits:

  • H1 The entropy of split 1;

  • H2 The entropy of split 2;

  • H12 The joint entropy of both splits;

  • I The mutual information of the splits;

  • Hd The entropy distance (variation of information) of the splits.


MacKay DJC (2003). Information Theory, Inference, and Learning Algorithms. Cambridge University Press, Cambridge.

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 .

See also

Other information functions: SplitSharedInformation(), TreeInfo


SplitEntropy(c(A, A, A, B, B, B), c(A, A, B, B, B, B))
#>        H1        H2       H12         I        Hd 
#> 1.0000000 0.9182958 1.4591479 0.4591479 1.0000000