A tree with two leaves:

A tree with multiple levels:

A tree with data in the leaves:

A tree containing another tree as data:

Represent a leaf with no child:

Specify children in a list:

Create a tree of life:

Create a tree of descendants:

Create a tree from the hierarchy of files in a directory:

Define a function that extracts the tag from an XMLElement:

Define a function that yields the child elements of an XMLElement:

Convert an XMLElement object to a tree:

Convert an XML tree to an XMLElement:

Define a function that extracts the data from a JSON rule:

Define a function that extracts the children from a JSON rule:

Convert JSON rules to a tree:

Convert a JSON tree to rules:

Define a function that converts a TextElement object to a tree:

Define a function that yields the child elements of a TextElement:

Define a function that extracts the "GrammaticalUnit" from a TextElement:

Convert TextElement to a tree:

Convert a text tree to a TextElement:

Get a list of US cities with populations over 100,000:

Construct a graph giving the hierarchical clustering of the cities according to their geodetic positions:

Convert the clustering hierarchy from a Graph object to a Tree object:

For each leaf, obtain the geodetic position of a city from its index in the hierarchical clustering graph:

For each subtree representing a cluster, give the tree containing the spatial median of its children:

Obtain a tree of geodetic positions by using the position of a city for each leaf and the spatial median of the positions for each cluster:

Show the edges in this tree of geodetic positions on a map of the United States:

Create a family tree:

Create an association giving the dates of birth:

Define a function that compares two people, giving the person who was younger when they had their first child, together with that child and their age when that child was born:

Define a function that compares two siblings, giving the older sibling together with their date of birth, in addition to the youngest first-time parent among their descendants:

Define a function that gives the youngest first-time parent among a person's descendants, given the results for their children:

Find the youngest first-time parent in the tree, together with their first child and their age when the child was born:

A root node of a tree does not need to have data:

RulesTree returns a Tree expression:

Check whether an expression with head Tree is a valid Tree object:

This is not a valid Tree object:

However, this is a valid Tree object that contains a child with an invalid Tree expression as data:

Construct a Tree expression with ExpressionTree:

Construct a Tree expression with GraphTree: