Description Usage Arguments Value Author(s) References Examples

This function calculates the Rogers J index *J(T)* for a given rooted
binary tree *T*. It is defined as the number of inner vertices whose balance
value is unequal to zero, more precisely

*J(T)=ā (1-I(n_{u_a}=n_{u_b})) over all u in V_in(T)*

in which *V_in(T)* denotes the set of all inner vertices
of *T*, and in which *n_ua*
and *n_ub* denote the number of leaves in the two pending subtrees that are
rooted at the direct descendants of *u*.

Special cases: For *n=1*, the function returns *J(T)=0* and a warning.

1 | ```
rogersI(tree)
``` |

`tree` |
A rooted binary tree in phylo format. |

`rogersI`

returns the Rogers J index of the given tree.

Sophie Kersting

J. S. Rogers. Central Moments and Probability Distributions of Three Measures of Phylogenetic Tree Imbalance. Systematic Biology, 45(1):99-110, 1996. doi: 10.1093/sysbio/45.1.99.

1 2 |

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