Tree Walking

class anytree.walker.Walker

Bases: object

Walk from one node to another.

walk(start, end)

Walk from start node to end node.

Returns:

(upwards, downwards): upwards is a list of edges to parent nodes to go upward to. downwards is a list of edges to child nodes to go downward to.

Raises:

WalkError: on no common root node.

>>> from anytree import Node, RenderTree, AsciiStyle
>>> f = Node("f")
>>> b = Node("b", parent=f)
>>> a = Node("a", parent=b)
>>> d = Node("d", parent=b)
>>> c = Node("c", parent=d)
>>> e = Node("e", parent=d)
>>> g = Node("g", parent=f)
>>> i = Node("i", parent=g)
>>> h = Node("h", parent=i)
>>> print(RenderTree(f, style=AsciiStyle()))
Node('/f')
|-- Node('/f/b')
|   |-- Node('/f/b/a')
|   +-- Node('/f/b/d')
|       |-- Node('/f/b/d/c')
|       +-- Node('/f/b/d/e')
+-- Node('/f/g')
    +-- Node('/f/g/i')
        +-- Node('/f/g/i/h')

Create a walker:

>>> w = Walker()

This class is made for walking:

>>> w.walk(f, f)
([], [])
>>> w.walk(f, b)
([], [Node('/f/b')])
>>> w.walk(b, f)
([Node('/f')], [])
>>> w.walk(a, f)
([Node('/f/b'), Node('/f')], [])
>>> w.walk(b, f)
([Node('/f')], [])
>>> w.walk(h, e)
([Node('/f/g/i'), Node('/f/g'), Node('/f')], [Node('/f/b'), Node('/f/b/d'), Node('/f/b/d/e')])

For a proper walking the nodes need to be part of the same tree:

>>> w.walk(Node("a"), Node("b"))
Traceback (most recent call last):
  ...
anytree.walker.WalkError: Node('/a') and Node('/b') are not part of the same tree.

exception anytree.walker.WalkError

Bases: exceptions.RuntimeError

Walk Error.