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abstracttree 0.0.5

This Python package contains a few abstract base classes for tree data structures.
Trees are very common data structure that represents a hierarchy of common nodes.
This package defines abstract base classes for these data structure in order to make code reusable.
Abstract base classes
from abstracttree import to_mermaid

to_mermaid(AbstractTree)

graph TD;
AbstractTree[AbstractTree];
UpTree[UpTree];
Tree[Tree];
MutableTree[MutableTree];
DownTree[DownTree];
Tree[Tree];
MutableTree[MutableTree];
MutableDownTree[MutableDownTree];
MutableTree[MutableTree];
BinaryDownTree[BinaryDownTree]
BinaryTree[BinaryTree]
AbstractTree-->UpTree;
UpTree-->Tree;
Tree-->MutableTree;
AbstractTree-->DownTree;
DownTree-->Tree;
DownTree-->MutableDownTree;
MutableDownTree-->MutableTree;
DownTree-->BinaryDownTree
BinaryDownTree-->BinaryTree
Tree-->BinaryTree

Downtrees are trees that have links to their direct children.
Uptrees are trees that link to their parent.
A Tree has links in both directions.

ABC
Inherits from
Abstract Methods
Mixin Methods

AbstractTree

nid, eqv()

UpTree
AbstractTree
parent
root, is_root, ancestors, path

DownTree
AbstractTree
children
nodes, descendants, leaves, levels, is_leaf, transform(), nodes.preorder(), nodes.postorder(), nodes.levelorder()

Tree
UpTree, DownTree

siblings

MutableDownTree
DownTree
add_child(), remove_child()
add_children()

MutableTree
Tree, MutableDownTree

detach()

BinaryDownTree
DownTree
left_child, right_child
children, nodes.inorder(), descendants.inorder()

BinaryTree
BinaryDownTree, Tree

In your own code, you can inherit from these trees.
For example, if your tree only has links to children:
import abstracttree
from abstracttree import print_tree

class MyTree(abstracttree.DownTree):
def __init__(self, value, children=()):
self.value = value
self._children = children

def __str__(self):
return "MyTree " + str(self.value)

@property
def children(self):
return self._children

tree = MyTree(1, children=[MyTree(2), MyTree(3)])
print_tree(tree)

# This generates the following output:
# MyTree 1
# ├─ MyTree 2
# └─ MyTree 3

Adapter
In practice, not all existing tree data structures implement one of these abstract classes.
As a bridge, you can use astree to convert these trees to a Tree instance.
However, whenever possible, it's recommended to inherit from Tree directly for minimal overhead.
Examples:
# Trees from built-ins and standard library
astree(int)
astree(ast.parse("1 + 1 == 2"))
astree(pathlib.Path("abstracttree"))

# Anything that has parent and children attributes (anytree / bigtree / littletree)
astree(anytree.Node())

# Nested list
astree([[1, 2, 3], [4, 5, 6]])

# Tree from json-data
data = {"name": "a",
"children": [
{"name": "b", "children": []},
{"name": "c", "children": []}
]}
astree(data, children=operator.itemgetter["children"])

# pyqt.QtWidget
astree(widget, children=lambda w: w.children(), parent = lambda w: w.parent())

# Tree from treelib
astree(tree.root, children=lambda nid: tree.children(nid), parent=lambda nid: tree.parent(nid))

# itertree
astree(tree, children=iter, parent=lambda t: t.parent)

# Infinite binary tree
inf_binary = astree(0, children=lambda n: (2*n + 1, 2*n + 2))

Utility functions
Pretty printing
tree = astree(seq, children=lambda x: [x[:-2], x[1:]] if x else [])
print_tree(tree)
print(to_string(tree))

# ['a', 'b', 'c', 'd']
# ├─ ['a', 'b']
# │ └─ ['b']
# └─ ['b', 'c', 'd']
# ├─ ['b']
# └─ ['c', 'd']
# └─ ['d']

Plotting with matplotlib
import matplotlib.pyplot as plt

expr = ast.parse("y = x*x + 1")
plot_tree(expr)
plt.show()

Export to various formats
to_dot(tree)
to_mermaid(tree)
to_latex(tree)

to_image(Path('.'), "filetree.png", how="dot")
to_image(AbstractTree, "class_hierarchy.svg", how="mermaid")
to_pillow(tree).show()

Find distance between nodes
import heapq

from abstracttree import HeapTree, Route

tree = HeapTree([5, 4, 3, 2, 1])
heapq.heapify(tree.heap)
left_child = tree.children[0]
right_child = tree.children[1]

route = Route(left_child, right_child)
print(f"{route.lca = }") # => HeapTree([1, 2, 3, 5, 4], 0)
print(f"{route.nodes.count() = }") # => 3
print(f"{route.edges.count() = }") # => 2

A few concrete tree implementations

anytree
treelib
bigtree
itertree
dendropy
ete
littletree - also by me

Tree visualisation

PrettyPrintTree - colored terminal output