anytree is splitted into the following parts:

Node Classes

  • Node: a simple tree node
  • NodeMixin: extends any python class to a tree node.

Node Resolution

  • Resolver: retrieve node via absolute or relative path.
  • Walker: walk from one node to an other.

Tree Iteration Strategies

Tree Rendering


The only tree relevant information is the parent attribute. If None the node is root node. If set to another node, the node becomes the child of it.

>>> udo = Node("Udo")
>>> marc = Node("Marc")
>>> lian = Node("Lian", parent=marc)
>>> print(RenderTree(udo))
>>> print(RenderTree(marc))
└── Node('/Marc/Lian')

Every node has an children attribute with a tuple of all children:

Every node has an children attribute with a tuple of all children:

>>> udo.children
>>> marc.children
>>> lian.children


>>> marc.parent = udo
>>> print(RenderTree(udo))
└── Node('/Udo/Marc')
    └── Node('/Udo/Marc/Lian')


To make a node to a root node, just set this attribute to None.

>>> marc.is_root
>>> marc.parent = None
>>> marc.is_root

Detach/Attach Protocol

A node class implementation might implement the notification slots _pre_detach(parent), _post_detach(parent), _pre_attach(parent), _post_attach(parent).

>>> class NotifiedNode(Node):
...     def _pre_detach(self, parent):
...         print("_pre_detach", parent)
...     def _post_detach(self, parent):
...         print("_post_detach", parent)
...     def _pre_attach(self, parent):
...         print("_pre_attach", parent)
...     def _post_attach(self, parent):
...         print("_post_attach", parent)

Notification on attach:

>>> a = NotifiedNode("a")
>>> b = NotifiedNode("b")
>>> c = NotifiedNode("c")
>>> c.parent = a
_pre_attach NotifiedNode('/a')
_post_attach NotifiedNode('/a')

Notification on change:

>>> c.parent = b
_pre_detach NotifiedNode('/a')
_post_detach NotifiedNode('/a')
_pre_attach NotifiedNode('/b')
_post_attach NotifiedNode('/b')

If the parent equals the old value, the notification is not triggered:

>>> c.parent = b

Notification on detach:

>>> c.parent = None
_pre_detach NotifiedNode('/b')
_post_detach NotifiedNode('/b')