M-Ary Tree

An implementation of an m-ary tree in TypeScript.

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Install

yarn add m-ary-tree

npm install m-ary-tree

Usage

For detailed use see the API Documentation

Basic

import { Tree } from 'm-ary-tree';

const tree = new Tree(0);

tree.insert(0, 1);
tree.insert(0, 2);

Keys

Each node inserted should have a unique key. Values are optional.

import { Tree } from 'm-ary-tree';

const tree = new Tree(0);

tree.insert(0, 1)          // node with key 1 and no data
tree.insert(0, 2, 'foo')   // node with key 2 and data foo

Binary / Ternary Trees

Use maxChildren option to limit child nodes, thus producing binary or ternary trees etc.

const tree = new Tree(1, null, {
  maxChildren: 2,
});

Traversals

All traversals are implemented as generators.

for (const node of tree.postOrderTraversal()) {
  // ...
}

Generic Types

TypeScript generics are supported:

type MyNodeType = string

const tree = new Tree<number, MyNodeType>(0, 'foo');

console.log(tree.data) // 'foo'

Motivation

This library was created while experimenting with tree drawing algorithms.

There are currently two positioning algorithms implemented:

• Node-Positioning Algorithm for General Trees by John Q. Walker
• Drawing Non-layered Tidy Trees in Linear Time by Atze van der Ploeg

Walker's Tree

In this implementation all nodes must be the same width and height.

import { calculateCoordinates } from 'm-ary-tree/dist/positioning-algorithms/Walker/calculateCoordinates';
import { Tree, preOrderTraversal } from 'm-ary-tree';

const tree = new Tree<number>(0);

tree.insert(0, 1);
tree.insert(0, 2);
tree.insert(0, 3);

calculateCoordinates(tree, {
  nodeWidth: 50,
  nodeHeight: 50,
  nodeSpacingX: 100,
  nodeSpacingY: 30,
});

const positionedTree = calculateCoordinates(tree);

for (const node of preOrderTraversal(positionedTree)) {
  expect(typeof node.data.x).toBe('number')
  expect(typeof node.data.y).toBe('number')
  expect(typeof node.data.width).toBe('number')
  expect(typeof node.data.height).toBe('number')
}

Ploeg's Tree

In this implementation all nodes can be different sizes.

import { calculateCoordinates } from 'm-ary-tree/dist/positioning-algorithms/Walker/calculateCoordinates';
import { Tree, preOrderTraversal } from 'm-ary-tree';

const tree = new Tree(0, {
  width: 60,
  height: 25,
});

tree.insert(0, 1, {
  width: 50,
  height: 20,
});

tree.insert(0, 2, {
  width: 50,
  height: 60,
});

const positionedTree = calculateCoordinates(tree, {
  nodeSpacingX: 100,
  nodeSpacingY: 30,
});

for (const node of preOrderTraversal(positionedTree)) {
  expect(typeof node.data.x).toBe('number')
  expect(typeof node.data.y).toBe('number')
  expect(typeof node.data.width).toBe('number')
  expect(typeof node.data.height).toBe('number')
}