Set Utilities

This library is a collection of utility functions that operate with JavaScript Sets.

Each function, as derived from Set Theory, is built to operate on n-ary sets by accepting variable arguments. Additionally, each function operates with the principals of immutability: none of the input sets are modified in the process or result of calculation.

Set Operations:

difference: A ∖ B

The difference of two sets contains all the elements of the first set that are not contained in the second (or thereafter).

import { difference } from 'set-utilities';

const differenceAB = difference(setA, setB);
const differenceABC = difference(setA, setB, setC);

intersection: A ∩ B

The intersection of two sets contains all the elements each contained in both of the sets.

import { intersection } from 'set-utilities';

const intersectionAB = intersection(setA, setB);
const intersectionABC = intersection(setA, setB, setC);

union: A ∪ B

The union of two sets contains all the elements contained in either set (or both sets).

import { union } from 'set-utilities';

const unionAB = union(setA, setB);
const unionABC = union(setA, setB, setC);

symmetric difference (xor): A ∆ B

The symmetric difference of two sets contains only the unique elements of each set.

import { xor } from 'set-utilities';

const xorAB = xor(setA, setB);
const xorABC = xor(setA, setB, setC);

Set Comparisons:

equivalence: A ∼ B

Sets are equivalent if they have the same cardinality, and there is a bijection between the values contained in each set.

import { equivalence } from 'set-utilities';

const isEquivalentAB = equivalence(setA, setB);
const isEquivalentABC = equivalence(setA, setB, setC);

disjoint: A ∩ B = ∅

Sets are disjoint if they have no elements in common.

import { disjoint } from 'set-utilities';

const isDisjointAB = disjoint(setA, setB);
const isDisjointABC = disjoint(setA, setB, setC);

subset: A ⊆ B

A set is a subset of another if all of its elements are elements of the other set.

import { subset } from 'set-utilities';

const isSubsetAB = subset(setA, setB);
const isSubsetABC = subset(setA, setB, setC);

proper subset: A ⊂ B

A set is a proper subset of another if all of its elements are elements of the other set, and it has a lower cardinality than the other set.

import { properSubset } from 'set-utilities';

const isProperSubsetAB = properSubset(setA, setB);
const isProperSubsetABC = properSubset(setA, setB, setC);

superset: A ⊇ B

A set is a superset of another if it contains all the elements contained in the other set.

import { superset } from 'set-utilities';

const isSupersetAB = superset(setA, setB);
const isSupersetABC = superset(setA, setB, setC);

proper superset: A ⊃ B

A set is a proper superset of another if it contains all the elements contained in the other set, and it has a greater cardinality than the other set.

import { properSuperset } from 'set-utilities';

const isProperSupersetAB = properSuperset(setA, setB);
const isProperSupersetABC = properSuperset(setA, setB, setC);

Set Ordering:

sort:

An immutable sorting operation for sets.

import { sort } from 'set-utilities';

const sorted = sort(setA);
const sortedByComparator = sort(setA, comparatorFunction);