tonal-pcset

pcset

tonal-pcset is a collection of functions to work with pitch class sets, oriented to make comparations (isEqual, isSubset, isSuperset)

This is part of tonal music theory library.

You can install via npm: npm i --save tonal-pcset

var pcset = require('tonal-pcset')
pcset.isEqual('c2 d5 e6', 'c6 e3 d1') // => true

API documentation

• pcset
  • .chroma(set) ⇒ String
  • .modes(set, normalize) ⇒ Array.<String>
  • .isChroma(chroma) ⇒ Boolean
  • .intervals(pcset) ⇒ Array
  • .isEqual(set1, set2) ⇒ Boolean
  • .isSubsetOf(set, notes) ⇒ boolean
  • .isSupersetOf(set, notes) ⇒ boolean
  • .includes(set, note) ⇒ Boolean
  • .filter(set, notes) ⇒ Array

pcset.chroma(set) ⇒ String

Get chroma of a pitch class set. A chroma identifies each set uniquely. It's a 12-digit binary each presenting one semitone of the octave.

Note that this function accepts a chroma as parameter and return it without modification.

Kind: static method of pcset
Returns: String - a binary representation of the pitch class set

Param	Type	Description
set	Array | String	the pitch class set

Example

pcset.chroma(["C", "D", "E"]) // => '1010100000000'

pcset.modes(set, normalize) ⇒ Array.<String>

Given a a list of notes or a pcset chroma, produce the rotations of the chroma discarding the ones that starts with '0'

This is used, for example, to get all the modes of a scale.

Kind: static method of pcset
Returns: Array.<String> - an array with all the modes of the chroma

Param	Type	Description
set	Array | String	the list of notes or pitchChr of the set
normalize	Boolean	(Optional, true by default) remove all the rotations that starts with '0'

Example

pcset.modes(["C", "D", "E"]).map(pcset.intervals)

pcset.isChroma(chroma) ⇒ Boolean

Test if the given string is a pitch class set chroma.

Kind: static method of pcset
Returns: Boolean - true if its a valid pcset chroma

Param	Type	Description
chroma	String	the pitch class set chroma

Example

pcset.isChroma('101010101010') // => true
pcset.isChroma('101001') // => false

pcset.intervals(pcset) ⇒ Array

Given a pcset (notes or chroma) return it's intervals

Kind: static method of pcset
Returns: Array - intervals or empty array if not valid pcset

Param	Type	Description
pcset	String | Array	the pitch class set (notes or chroma)

Example

pcset.intervals('1010100000000') => ["1P", "2M", "3M"]

pcset.isEqual(set1, set2) ⇒ Boolean

Test if two pitch class sets are identical

Kind: static method of pcset
Returns: Boolean - true if they are equal

Param	Type	Description
set1	Array | String	one of the pitch class sets
set2	Array | String	the other pitch class set

Example

pcset.isEqual(["c2", "d3"], ["c5", "d2"]) // => true

pcset.isSubsetOf(set, notes) ⇒ boolean

Create a function that test if a collection of notes is a subset of a given set

The function can be partially applied

Kind: static method of pcset
Returns: boolean - true if notes is a subset of set, false otherwise

Param	Type	Description
set	Array | String	an array of notes or a chroma set string to test against
notes	Array | String	an array of notes or a chroma set

Example

const inCMajor = pcset.isSubsetOf(["C", "E", "G"])
inCMajor(["e6", "c4"]) // => true
inCMajor(["e6", "c4", "d3"]) // => false

pcset.isSupersetOf(set, notes) ⇒ boolean

Create a function that test if a collectio of notes is a superset of a given set (it contains all notes and at least one more)

Kind: static method of pcset
Returns: boolean - true if notes is a superset of set, false otherwise

Param	Type	Description
set	Array | String	an array of notes or a chroma set string to test against
notes	Array | String	an array of notes or a chroma set

Example

const extendsCMajor = pcset.isSupersetOf(["C", "E", "G"])
extendsCMajor(["e6", "a", "c4", "g2"]) // => true
extendsCMajor(["c6", "e4", "g3"]) // => false

pcset.includes(set, note) ⇒ Boolean

Test if a given pitch class set includes a note

Kind: static method of pcset
Returns: Boolean - true if the note is included in the pcset

Param	Type	Description
set	Array | String	the base set to test against
note	String | Pitch	the note to test

Example

pcset.includes(["C", "D", "E"], 'C4') // => true
pcset.includes(["C", "D", "E"], 'C#4') // => false

pcset.filter(set, notes) ⇒ Array

Filter a list with a pitch class set

Kind: static method of pcset
Returns: Array - the filtered notes

Param	Type	Description
set	Array | String	the pitch class set notes
notes	Array | String	the note list to be filtered

Example

pcset.filter(["C", "D", "E"], ["c2", "c#2", "d2", "c3", "c#3", "d3"]) // => [ 'c2', 'd2', 'c3', 'd3' ])
pcset.filter(["C2"], ["c2", "c#2", "d2", "c3", "c#3", "d3"]) // => [ 'c2', 'c3' ])