Installation

$ npm install covertable --save

Usage

Simple demo in Node.js:

var module = require('covertable');
var make = module.default;

var machine = ['iphone', 'pixel'];
var os = ['ios', 'android'];
var browser = ['FireFox', 'Chrome', 'Safari'];

make([machine, os, browser]);

Output:

[
  [ 'iphone', 'android', 'Safari' ],
  [ 'iphone', 'ios', 'FireFox' ],
  [ 'iphone', 'android', 'Chrome' ],
  [ 'pixel', 'ios', 'Chrome' ],
  [ 'pixel', 'android', 'FireFox' ],
  [ 'pixel', 'ios', 'Safari' ]
]

Advanced demo in TypeScript:

import { default as make, sorters, criteria } from "covertable";

const machine = ['iphone', 'pixel'];
const os = ['ios', 'android'];
const browser = ['FireFox', 'Chrome', 'Safari'];

make([machine, os, browser], { // optional
  length: 2, // default: 2
  criterion: criteria.simple, // default: criteria.greedy
  sorter: sorters.random, // default: sorters.hash
  preFilter: (row: any) => !(row[1] === 'android' && row[0] !== 'pixel'), // default: null
  postFilter: (row: any) => !(row[1] === 'ios' && row[2] !== 'Safari'), // default: null
});

Output:

[ // filtered
  [ 'pixel', 'android', 'Safari' ],
  [ 'iphone', 'ios', 'Safari' ]
]

Object input and output

You can specify factors as object type:

import { default as make, sorters, criteria } from "covertable";

const machine = ['iphone', 'pixel'];
const os = ['ios', 'android'];
const browser = ['FireFox', 'Chrome', 'Safari'];

make({machine, os, browser}, { // optional
  length: 2, // default: 2
  seed: 100,
  preFilter: (row: any) => !(row.os === 'android' && row.machine !== 'pixel'), // default: null
  postFilter: (row: any) => !(row.os === 'ios' && row.browser !== 'Safari'), // default: null
});

Then the output will change as follows:

[ // filtered
  { os: 'ios', browser: 'Safari', machine: 'iphone' },
  { machine: 'pixel', browser: 'Safari', os: 'android' }
]

Warning: Order of object iteration is not guaranteed in TypeScript(JavaScript). So even if factors and seed are not changed, output combination is not necessarily the same.

Options

covertable.make function has options as object at 2nd argument.

All options are omittable.

length

It means length of pair to meet. (default: 2)

The more it increases, the more number of combinations increases.

sorter

Combinations depend on the order of spreading all over the rows.

You can choice a sorter from the following:

• sorters.random: It makes different combinations everytime. (fastest)

• sorters.hash: It makes combinations depending on hash of the pair and seed. (default)

  • It receives seed and useCache.

    • seed option decides the order of storing from unstored pairs, therefore it outputs the same result every time when number of factors and seed are the same.
    • useCache option decide if using cache of hash or not. (default: true)
      • It is around 30% faster than setting useCache off.

criterion

• criteria.simple: This criterion extracts any pairs that can be stored into the processing row.
• criteria.greedy: This criterion attempts to make most efficient combinations. (default)
  • These combinations are not always shorter than simple criterion.
  • It receives tolerance option.

Not relevant options will be ignored.

preFilter

This means a function to filter beforehand.

It receives an argument row as object type.

When the function returns false, the row combination will not registered.

• If factors type is Array, you should specify an index at the subscript like row => row[1] < 6.
• If factors type is Object, you should specify a key at the subscript like row => row.month < 6 or row => row['month'] < 6

postFilter

This means a function to filter later.

Usage is the same as preFilter, only the difference is the timing that it is called. It will delete rows not matched this function at the last.

Requirement

ES2015 or later

• Generator
• for...of
• Map
• Set
• Object.keys
• Object.entries

Development

$ npm install

Testing

$ npm test -- --coverage

Publish

$ # npm adduser
$ npm run build
$ npm version patch
$ npm publish

More info

• walkframe/covertable - GitHub