pytreeds

A dependency-free Python library for beginners to create, inspect, modify, traverse, and print non-binary trees. Students keep only one tree variable. Node identifiers are unique strings, and all node-related operations return strings rather than mixed types.

Install

pip install pytreeds

Pyodide (from your platform's asynchronous package loader):

import micropip
await micropip.install("pytreeds")

First example

from pytreeds import Tree

org = Tree("CEO")
org.add_nodes(["CTO", "CFO", "COO"], parent="CEO")
org.add_nodes(["Engineering", "DevOps"], parent="CTO")
org.add_node("Accounting", parent="CFO")

org.show()
print(org.height())                # 2 edges
print(org.size())                  # 6
print(org.children("CTO"))         # ['Engineering', 'DevOps']
print(org.parent("DevOps"))        # CTO
print(org.leaves())
print(list(org.dfs()))
print(list(org.bfs()))

for name in org:
    print(name, "->", org.parent(name))

Text diagram:

CEO
├── CTO
│   ├── Engineering
│   └── DevOps
├── CFO
│   └── Accounting
└── COO

API reference

Build and modify

Properties and relationships

Traversal and search

Print text

The style option can also be "ascii".

Design and errors

• Each node has a unique nonempty string name. No UUIDs, extra node variables, overloaded subscripts, or student-defined classes.
• Parent, children, leaves, DFS, BFS, and ordinary iteration consistently use strings.
• The first node is the root. Further additions need a parent.
• Children and traversals preserve insertion order.
• Height and depth count edges, not levels.
• Duplicate names and invalid moves raise ValueError; missing names raise KeyError.
• Batch insertions validate before modifying the tree.
• Avoid modifying the tree while looping over a traversal.

Subtree example

from pytreeds import Tree
org = Tree("CEO")
org.add_nodes(["CTO", "CFO"], parent="CEO")
org.add_node("DevOps", parent="CTO")
org.move_node("DevOps", parent="CFO")
org.rename_node("DevOps", "Infrastructure")
org.show()
print(org.path("Infrastructure"))
org.remove_subtree("CFO")

Run tests locally using: python -m unittest discover -s tests -v

This repository intentionally keeps the existing publishing-only GitLab CI workflow; there is no testing CI job.