group-array

group-array

Group array of objects into lists.

Table of Contents

• Install
• Usage
• Examples
• About
  • Related projects
  • Contributing
  • Building docs
  • Running tests
  • Author
  • License

(TOC generated by verb using markdown-toc)

Install

Install with npm:

$ npm install --save group-array

Usage

var groupArray = require('group-array');

Examples

var arr = [
  {tag: 'one', content: 'A'},
  {tag: 'one', content: 'B'},
  {tag: 'two', content: 'C'},
  {tag: 'two', content: 'D'},
  {tag: 'three', content: 'E'},
  {tag: 'three', content: 'F'}
];

// group by the `tag` property
groupArray(arr, 'tag');

results in:

{
  one: [
    {tag: 'one', content: 'A'},
    {tag: 'one', content: 'B'}
  ],
  two: [
    {tag: 'two', content: 'C'},
    {tag: 'two', content: 'D'}
  ],
  three: [
    {tag: 'three', content: 'E'},
    {tag: 'three', content: 'F'}
  ]
}

Group by multiple, deeply nested properties

// given an array of object, like blog posts...
var arr = [
  { data: { year: '2014', tag: 'one', month: 'jan', day: '01'}, content: '...'},
  { data: { year: '2014', tag: 'one', month: 'jan', day: '01'}, content: '...'},
  { data: { year: '2014', tag: 'one', month: 'jan', day: '02'}, content: '...'},
  { data: { year: '2014', tag: 'one', month: 'jan', day: '02'}, content: '...'},
  { data: { year: '2014', tag: 'one', month: 'feb', day: '10'}, content: '...'},
  { data: { year: '2014', tag: 'one', month: 'feb', day: '10'}, content: '...'},
  { data: { year: '2014', tag: 'one', month: 'feb', day: '12'}, content: '...'},
  { data: { year: '2014', tag: 'one', month: 'feb', day: '12'}, content: '...'},
  { data: { year: '2014', tag: 'two', month: 'jan', day: '14'}, content: '...'},
  { data: { year: '2014', tag: 'two', month: 'jan', day: '14'}, content: '...'},
  { data: { year: '2014', tag: 'two', month: 'jan', day: '16'}, content: '...'},
  { data: { year: '2014', tag: 'two', month: 'jan', day: '16'}, content: '...'},
  { data: { year: '2014', tag: 'two', month: 'feb', day: '18'}, content: '...'},
  { data: { year: '2015', tag: 'two', month: 'feb', day: '18'}, content: '...'},
  { data: { year: '2015', tag: 'two', month: 'feb', day: '10'}, content: '...'},
  { data: { year: '2015', tag: 'two', month: 'feb', day: '10'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'jan', day: '01'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'jan', day: '01'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'jan', day: '02'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'jan', day: '02'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'feb', day: '01'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'feb', day: '01'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'feb', day: '02'}, content: '...'},
  { data: { year: '2015', tag: 'three', month: 'feb', day: '02'}, content: '...'}
]

Pass a list or array of properties:

groupArray(arr, 'data.year', 'data.tag', 'data.month', 'data.day');

Results in something like this: (abbreviated)

{
  '2014':
   { one:
      { jan:
         { '01':
            [ { data: { year: '2014', ... },
              { data: { year: '2014', ... } ],
           '02':
            [ { data: { year: '2014', ... },
              { data: { year: '2014', ... } ] },
        feb:
         { '10':
            [ { data: { year: '2014', ... },
              { data: { year: '2014', ... } ],
           '12':
            [ { data: { year: '2014', ... },
              { data: { year: '2014', ... } ] } },
     two:
      { jan:
         { '14':
            [ { data: { year: '2014', ... },
              { data: { year: '2014', ... } ],
           '16':
            [ { data: { year: '2014', ... },
              { data: { year: '2014', ... } ] },
        feb:
         { '18':
            [ { data: { year: '2014', ... } ] } } },
  '2015':
   { two:
      { feb:
         { '10':
            [ { data: { year: '2015', ... },
              { data: { year: '2015', ... } ],
           '18':
            [ { data: { year: '2015', ... } ] } },
     three:
      { jan:
         { '01':
            [ { data: { year: '2015', ... },
              { data: { year: '2015', ... } ],
           '02':
            [ { data: { year: '2015', ... },
              { data: { year: '2015', ... } ] },
        feb:
         { '01':
            [ { data: { year: '2015', ... },
              { data: { year: '2015', ... } ],
           '02':
            [ { data: { year: '2015', ... },
              { data: { year: '2015', ... } ] } } }};

About

Related projects

• arr-reduce: Fast array reduce that also loops over sparse elements. | homepage
• get-value: Use property paths (a.b.c) to get a nested value from an object. | homepage
• group-object: Group object keys and values into lists. | homepage
• union-value: Set an array of unique values as the property of an object. Supports setting deeply… more | homepage

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.

Building docs

(This document was generated by verb-generate-readme (a verb generator), please don't edit the readme directly. Any changes to the readme must be made in .verb.md.)

To generate the readme and API documentation with verb:

$ npm install -g verb verb-generate-readme && verb

Running tests

Install dev dependencies:

$ npm install -d && npm test

Author

Brian Woodward

• github/doowb
• twitter/doowb

License

Copyright © 2016, Brian Woodward. Released under the MIT license.

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This file was generated by verb, v0.9.0, on July 15, 2016.