Documentation¶
This module provides a Node class, node functions, and tree functions for a binary tree data structure.
Example
from binary_tree import from_string, from_orders, traverse
node = from_string("1,2,,3,4,,5")
in_order = list(traverse(node, "in"))
pre_order = list(traverse(node, "pre"))
node2 = from_orders("inpre", in_order, pre_order)
>>> repr(node) == repr(node2)
True
Node¶

class
binary_tree.
Node
(value, **nodes)[source]¶ The basic unit of a binary tree structure.

value
¶ The node value.

Comparing the value of a Node instance¶
Getting the binary tree structure of a Node instance¶
node¶
This module contains functions for the Node class.
Checking for a Node instance¶
Checking for a child Node instance¶
Checking for a Node instance in a binary tree structure¶

binary_tree.node.
is_leaf
(node)[source]¶ Check if node is a leaf node.
Returns: True
if node has aparent
but noleft
orright
node,False
otherwise.
tree¶
This module contains functions for binary trees.
Constructing a Node instance with a binary tree structure¶

binary_tree.tree.
from_string
(tree_string, cls=<class 'binary_tree.node.Node'>)[source]¶ Construct a
Node
instance with the binary tree structure represented by tree_string.Initializes the root
Node
instance (the first level), followed byleft
and thenright
for everyNode
instance per level (levelorder).Parameters:  tree_string (str) – A levelorder binary tree traversal, separated by commas.
 cls (type) – The class constructor to use. Defaults to
Node
.
Returns: A newly initialized cls instance with the binary tree structure that represents tree_string. If tree_string has no root value, returns
None
.Note
Empty spaces can be represented by an immediate comma or
"null"
for explicitness.

binary_tree.tree.
from_orders
(kind, in_order, other_order, cls=<class 'binary_tree.node.Node'>)[source]¶ Construct a
Node
instance with the binary tree structure that entails inorder and other_order.Recursively initializes
parent
,left
, and thenright
. (preorder).Parameters:  kind (str) – Either “inpre” or “inpost”.
 in_order (list[int, ..]) – The inorder traversal of a binary tree.
 other_order (list[int, ..]) – Either the tree’s preorder or postorder traversal.
 cls (type) – The class constructor to use. Defaults to
Node
.
Returns: A newly initialized cls instance with the binary tree structure that entails in_order and other_order. If either arguments are empty, returns
None
.Raises: ValueError
– If in_order and other_order do not correspond to a binary tree structure or contain duplicates.KeyError
– If kind is not one of the accepted keys.
Note
There cannot be any duplicates in in_order and other_order.
Traversing a Node instance with a binary tree structure¶

binary_tree.tree.
traverse_pre_order
(root)[source]¶ Traverse root in preorder.
Visit
parent
,left
, and thenright
.Parameters: root – A root Node
instance.Yields: A Node
instance in the binary tree structure of root.

binary_tree.tree.
traverse_in_order
(root)[source]¶ Traverse root in inorder.
Visit
left
,parent
, and thenright
.Parameters: root – A root Node
instance.Yields: A Node
instance in the binary tree structure of root.

binary_tree.tree.
traverse_post_order
(root)[source]¶ Traverse root in postorder.
Visit
left
,right
, and thenparent
.Parameters: root – A root Node
instance.Yields: A Node
instance in the binary tree structure of root.

binary_tree.tree.
traverse_level_order
(root)[source]¶ Traverse root in levelorder.
Visit root (the first level), followed by
left
and thenright
for everyNode
instance per level.Parameters: root – A root Node
instance.Yields: A list of Node
instances representing a level in root.

binary_tree.tree.
traverse
(root, kind)[source]¶ Forward root to the kind of traversal.
Parameters:  root – A root
Node
instance.  kind (str) – “pre” or “in” or “post” or “level”.
Returns: The generator iterator of the kind of traversal (with root passed to it).
Raises: KeyError
– If kind is not one of the possible options. root – A root
Analyzing a Node instance with a binary tree structure¶

binary_tree.tree.
is_symmetrical
(root)[source]¶ Check for symmetry in root.
Parameters: root – A root Node
instance.Returns: True
if the binary tree structure of root is symmetrical,False
otherwise.

binary_tree.tree.
max_depth
(root)[source]¶ Calculate the maximum depth of root.
Parameters: root – A root Node
instance.Returns: The total number of levels in the binary tree structure of root. Return type: int

binary_tree.tree.
get_path
(node)[source]¶ Trace the ancestry of node.
Parameters: node – A Node
instance in a binary tree.Returns: A list of Node
instances from the greatest ancestor to node.

binary_tree.tree.
all_paths
(root)[source]¶ Find every leaf path in root.
Search for leaf nodes in root using postorder traversal.
Parameters: root – A root Node
instance.Yields: A list of Node
instances from root to a leafNode
instance.

binary_tree.tree.
has_sum
(root, value)[source]¶ Determine if there is a path in root that adds up to value.
Parameters:  root – A root
Node
instance.  value – The sum to check for.
Returns: True
if a path that adds up to value exists in root,False
otherwise. root – A root

binary_tree.tree.
find_path
(root, node)[source]¶ Find the path of (the
Node
instance of) node in root.Parameters: Returns: A list of every
Node
instance from root to (theNode
instance of) node, orNone
if node is absent in root.Note
If node is a value, it must be unique within the binary tree structure of root.

binary_tree.tree.
get_lca
(root, *nodes)[source]¶ Get the lowest common ancestor of two or more (
Node
instances of) nodes in root.Parameters: Returns: The
Node
instance that is the lowest common ancestor of (theNode
instances of) nodes in root, orNone
if there is no common ancestor.Note
Values in nodes must be unique within the binary tree structure of root.