@emilbayes/multiset

Multiset implementation

Usage

const Multiset = require('@emilbayes/multiset')

const m = new Multiset([1, 1, 2, 3, 4, 4, 3, 8, 1])

console.log(m.count(1)) // => 3
console.log(m.count(4)) // => 2
console.log(m.size) // => 9
console.log(m.uniqueSize) // => 5

m.add(10)
console.log(m.size) // => 10
console.log(m.uniqueSize) // => 6

API

var m = new Multiset([elements = []], [key = x => x])

Create a new Multiset with optional initial array of elements, and optional identity key, which defaults to strict equality.

const size = m.size

Number of total elements in the Multiset.

const size = m.uniqueSize

Number of unique elements in the Multiset.

const m = m.add(elm, [n = 1])

Add elm to the Multiset, with optional multiplicity n. Equality is checked with key.

const m = m.delete(elm, [n = 1])

Delete elm from the Multiset, optionally decrementing by n. If final count is 0 or less, the element is removed from the Multiset. Equality is checked with key.

const bool = m.has(elm)

Check for existence.

const n = m.count(elm)

Count occurrences of elm in the Multiset.

const bool = m.equal(rhs)

Check if m and rhs contain the same elements with same multiplicity.

const bool = m.subset(superset)

Check if m is a subset of superset, meaning superset contain the same elements with at least the least the same multiplicity as m.

const m2 = m.filter(fn)

Filter unique elements from the Multiset, preserving count in the new Multiset. A new Multiset is created but if the elements are not primitives, they will share references between the two Multisets.

const m2 = m.difference(rhs)

Find the difference m \ rhs, copying the Multiset with the difference contained in the new Multiset. rhs can either be a Multiset or an Array.

m.forEach(fn, this)

Iterate elements of the Multiset as an array, meaning elements with multiplicity will be enumerated n times.

const arr = m.map(fn, this)

Map elements of the Multiset as an array, meaning elements with multiplicity will be enumerated n times. Returns the resulting array.

const arr = m.reduce(fn, [initialValue])

Reduce elements of the Multiset as an array, meaning elements with multiplicity will be enumerated n times. Returns the resulting accumulated value.

const m2 = m.clone()

Clone the Multiset. A new Multiset is created but if the elements are not primitives, they will share references between the two Multisets.

for (const elm of m) ...

Iterate elements of the Multiset with multiplicity.

const iterator = m.entries()

Iterate [elm, multiplicity] of the Multiset.

const iterator = m.counts()

Iterate multiplicity of the Multiset.

const iterator = m.values()

Iterate unqiue elm of the Multiset.

Install

npm install @emilbayes/multiset

License

ISC