https://github.com/blakek/partition
🗂 Partition an array or other iterable into two or more parts
https://github.com/blakek/partition
Last synced: about 1 month ago
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🗂 Partition an array or other iterable into two or more parts
- Host: GitHub
- URL: https://github.com/blakek/partition
- Owner: blakek
- License: mit
- Created: 2020-07-20T20:59:05.000Z (about 6 years ago)
- Default Branch: master
- Last Pushed: 2023-01-06T12:00:07.000Z (over 3 years ago)
- Last Synced: 2025-11-12T06:03:16.817Z (9 months ago)
- Language: TypeScript
- Size: 1.13 MB
- Stars: 2
- Watchers: 0
- Forks: 0
- Open Issues: 12
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# partition
> 🗂 Partition an array or other iterable into two or more parts
`partition()` is like `[].filter()` except you get the `true` and `false`
results as separate arrays.
`partitionMap()` is like `partition()`, but instead of `true`/`false`, results
are grouped by the return value of the passed function.
## Install
Using [Yarn]:
```bash
$ yarn add @blakek/partition
```
…or using [npm]:
```bash
$ npm i --save @blakek/partition
```
## Usage
```js
import { partition, partitionMap } from '@blakek/partition';
const isEven = n => n % 2 === 0;
const [even, odd] = partition([1, 2, 3, 4, 5], isEven);
console.log(even); //» [2, 4]
console.log(odd); //» [1, 3, 5]
const scores = [
{ initials: 'ABC', score: 125 },
{ initials: 'CBK', score: 920 },
{ initials: 'ABC', score: 123 },
{ initials: 'CBD', score: 420 },
{ initials: 'CBK', score: 1000 }
];
partitionMap(scores, x => x.initials);
//» Map {
//» 'ABC' => [ { initials: 'ABC', score: 125 }, { initials: 'ABC', score: 123 } ],
//» 'CBK' => [ { initials: 'CBK', score: 920 }, { initials: 'CBK', score: 1000 } ],
//» 'CBD' => [ { initials: 'CBD', score: 420 } ]
//» }
```
## API
### `partition`
```ts
function partition(
iterable: Iterable,
partitionFunction: (value?: T, index?: number, array?: T[]) => boolean
): [T[], T[]];
```
Splits an array into two parts: those where the partition function was truthy,
and those where it was falsy.
### `partitionMap`
```ts
function partitionMap(
iterable: Iterable,
partitionFunction: (value?: T, index?: number, array?: T[]) => U
): Map;
```
Creates a `Map` from the returns of the partition function.
```js
partitionMap([1, 2, 3, 4, 5], n => n % 2 == 0);
//» Map(2) { false => [ 1, 3, 5 ], true => [ 2, 4 ] }
const name = n => {
if (n < 3) return 'small';
if (n < 7) return 'medium';
return 'large';
};
partitionMap(new Set([1, 2, 3, 4, 5, 6, 7, 8]), n => name(n));
//» Map(3) {
//» 'small' => [ 1, 2 ],
//» 'medium' => [ 3, 4, 5, 6 ],
//» 'large' => [ 7, 8 ]
//» }
```
## Contributing
[Node.js] and [Yarn] are required to work with this project.
To install all dependencies, run:
```bash
yarn
```
### Useful Commands
| | |
| ------------------- | ----------------------------------------------- |
| `yarn build` | Builds the project to `./dist` |
| `yarn format` | Format the source following the Prettier styles |
| `yarn test` | Run project tests |
| `yarn test --watch` | Run project tests, watching for file changes |
## License
MIT
[node.js]: https://nodejs.org/
[npm]: https://npmjs.com/
[yarn]: https://yarnpkg.com/en/docs/