https://github.com/jcoreio/find-cycle

find and identify a cycle in a directed graph
https://github.com/jcoreio/find-cycle

cycle cycles cyclic detect detection detector directed directed-graph discord find finder graph graphs javascript js search

Last synced: about 2 months ago
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find and identify a cycle in a directed graph

• Host: GitHub
• URL: https://github.com/jcoreio/find-cycle
• Owner: jcoreio
• License: mit
• Created: 2018-01-28T17:50:09.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2023-11-07T22:18:09.000Z (about 1 year ago)
• Last Synced: 2024-11-07T01:06:42.788Z (3 months ago)
• Topics: cycle, cycles, cyclic, detect, detection, detector, directed, directed-graph, discord, find, finder, graph, graphs, javascript, js, search
• Language: JavaScript
• Size: 963 KB
• Stars: 15
• Watchers: 5
• Forks: 0
• Open Issues: 21
• Metadata Files:
  • Readme: README.md
  • License: LICENSE.md

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README

        
# find-cycle

[![Build Status](https://travis-ci.org/jcoreio/find-cycle.svg?branch=master)](https://travis-ci.org/jcoreio/find-cycle)

[![Coverage Status](https://codecov.io/gh/jcoreio/find-cycle/branch/master/graph/badge.svg)](https://codecov.io/gh/jcoreio/find-cycle)

[![semantic-release](https://img.shields.io/badge/%20%20%F0%9F%93%A6%F0%9F%9A%80-semantic--release-e10079.svg)](https://github.com/semantic-release/semantic-release)

[![Commitizen friendly](https://img.shields.io/badge/commitizen-friendly-brightgreen.svg)](http://commitizen.github.io/cz-cli/)

Searches for a cycle in a directed graph, and tells you the nodes in the

first cycle it finds. Should work on your existing data structures

without conversion, because it operates on `Iterables` and a

`getConnectedNodes` adapter function that you provide.

The implementation is a depth-first search using a stack instead of

recursion, so it's not limited by the maximum call stack size.

# Compatibility

Your environment must support `Set`, `Map`, and `Symbol.iterator`

natively or via a polyfill.

**Node**: 4+

# Installation

```sh

npm install --save find-cycle

```

# API

## `findDirectedCycle(startNodes, getConnectedNodes)`

```js

const findDirectedCycle = require('find-cycle/directed')

```

### Arguments

#### `startNodes: Iterable`

The nodes to start the search from. Your nodes may be of any primitive

or object type besides `null` or `undefined`.

#### `getConnectedNodes: (node: Node) => ?(Iterator | Iterable)`

Given a node in your directed graph, return the nodes connected to it as

an `Iterator` or `Iterable`. You may return `null` or `undefined` if

there are no connected nodes.

### Returns: `?Array`

An array of nodes in the first cycle found, if any, including each node

in the cycle only once.

## Examples

### With Arrays

```js

const findCycle = require('find-cycle/directed')

const edges = {

  1: [2],

  2: [3],

  3: [4],

  4: [2, 5],

  5: [3],

  7: [8, 9],

  8: [1],

  9: [10, 11],

  10: [11],

  11: [9, 8],

}

const startNodes = [1]

const getConnectedNodes = (node) => edges[node]

expect(findCycle(startNodes, getConnectedNodes)).to.deep.equal([2, 3, 4])

```

### With Sets/Maps

```js

const findCycle = require('find-cycle/directed'

const edges = new Map([

  [1, new Set([2])],

  [2, new Set([3])],

  [3, new Set([4])],

  [4, new Set([2, 5])],

  [5, new Set([3])],

  [7, new Set([8, 9])],

  [8, new Set([1])],

  [9, new Set([10, 11])],

  [10, new Set([11])],

  [11, new Set([9, 8])],

])

const startNodes = new Set([1])

const getConnectedNodes = node => edges.get(node)

expect(findCycle(startNodes, getConnectedNodes)).to.deep.equal([2, 3, 4])

```