Description Usage Arguments Value Author(s) References Examples

This function calculates the *B1* index *B1(T)* for a given rooted
tree *T*. The tree must not necessarily be binary. *B1(T)* is defined as

*
B1(T)=ā_{u in V'_in(T)} h(T_u)^(-1)*

in which
*V'_in(T)* denotes the set of inner vertices of *T* without the root, and
*h(T_u)* denotes the height of the pending subtree rooted at *u*.
When restricted to binary trees, the *B1* index is a balance index. For
arbitrary trees it does not fulfill the definition of an (im)balance index.

For *n=1* the function returns *B1(T)=0* and a warning.

1 | ```
B1I(tree)
``` |

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

`B1I`

returns the B1 index of the given tree.

Sophie Kersting

K.-T. Shao and R. R. Sokal. Tree Balance. Systematic Zoology, 39(3):266, 1990.

doi: 10.2307/2992186.

1 2 |

treebalance documentation built on Oct. 17, 2021, 5:06 p.m.

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