Basics#

Adding Nodes#

Nodes are usually created by adding a new data instance to a parent:

from nutree import Tree, Node

tree = Tree("Store")

n = tree.add("Records")

n.add("Let It Be")
n.add("Get Yer Ya-Ya's Out!")

n = tree.add("Books")
n.add("The Little Prince")

tree.print()

Tree<'Store'>
├── 'Records'
│   ├── 'Let It Be'
│   ╰── "Get Yer Ya-Ya's Out!"
╰── 'Books'
    ╰── 'The Little Prince'

Info and Navigation#

Tree statistics and related nodes are accessible like so:

assert tree.count == 5

records_node = tree["Records"]
assert tree.first_child() is records_node

assert len(records_node.children) == 2
assert records_node.depth() == 1

assert tree.find("Records") is records_node
assert tree.find("records") is None  # case-sensitive

n = records_node.first_child()
assert records_node.find("Let It Be") is n

assert n.name == "Let It Be"
assert n.depth() == 2
assert n.parent is records_node
assert n.prev_sibling() is None
assert n.next_sibling().name == "Get Yer Ya-Ya's Out!"
assert not n.children

Iteration#

Iterators are available for the hole tree or by branch. Different traversal methods are supported:

for node in tree:
    # Depth-first, pre-order by default
    ...

# Alternatively use `visit` with a callback:

def callback(node, memo):
    if node.name == "secret":
        # Prevent visiting the child nodes:
        return SkipBranch
    if node.data.foobar == 17:
        raise StopTraversal("found it")

# `res` contains the value passed to the `StopTraversal` constructor
res = tree.visit(callback)  # res == "found it"