pcset

@tonaljs/pcset

Functions to create and manipulate musical pitch class sets

A pitch class set is a set (no repeated) of pitch classes (notes without octaves). Pitch classes are useful to identify musical structures (if two chords are related, for example)

Usage

ES6:

import { Pcset } from "tonal";

nodejs:

const { Pcset } = require("tonal");

API

get(src: note[] | string | number)

Given a collection of notes, a pitch class chroma string or a pitch class number, it returns a properties object with the following attributes:

• num: the set number. Each pitch class set can be represented by an unique name between 0 and 4096. Those are the possible combinations of 12 different elements (pitch classes)
• chroma: the set number as binary string
• intervals: the list of intervals starting from C
• length: the number of notes

Example:

Pcset.get(["c", "d", "e"]);
// =>
// {
//   num: 2688,
//   chroma: "101010000000",
//   intervals: ["1P", "2M", "3M"],
//   length: 3
// }

It is possible to obtain the properties from chroma or set number. All this function calls returns the same object:

Pcset.get(["c", "d", "e"]);
Pcset.get(2688);
Pcset.get("101010000000");

Several shorthands (num, chroma, intervals`) are provided:

Pcset.chroma(["c", "d", "e"]); //=> "101010000000"
Pcset.num(["c", "d", "e"]); //=> 2192

// several set representations are accepted
Pcset.chroma(2192); //=> "101010000000"
Pcset.num("101010000000"); // => 2192

Intervals are always calculated from C:

Pcset.intervals(["c", "d", "e"]); // => ["1P", "5P", "7M"]
Pcset.intervals(["D", "F", "A"]); // => ["2M", "4P", "6M"]

notes(pcset: string | number | string[]) => string[]

Given a pcset or a list of notes, it returns the sorted pitch class notes:

Pcset.notes(["D3", "A3", "Bb3", "C4", "D4", "E4", "F4", "G4", "A4"]); // => ["C", "D", "E", "F", "G", "A", "Bb"]
Pcset.notes("101011010110"); // => ["C", "D", "E", "F", "G", "A", "Bb"]

isIncludedIn(parent: Set) => (note: string) => boolean

Test if a note is included in the given set. This function is currified:

const isInCTriad = isNoteIncludedIn(["C", "E", "G"]);
isInCTriad("C4"); // => true
isInCTriad("C#4"); // => false

Keep in mind that enharmonics are included:

isInCTriad("Fb"); // => true

isSubsetOf(parent: Set) => (subset: Set) => boolean

Test if a set is a subset of another. This function is currified

isSupersetOf(subset: Set) => (parent: Set) => boolean

Test if a set is a superset of another. This function is currified

Want more?

Take a look to @tonal/scale-type or @tonal/chord-type that are, in fact, dictionaries of pitch class sets.

FAQ

How do I get a list of all possible music scales?

import { chromas, pcset } from "@tonaljs/pcset";
import { transposeFrom } from "@tonaljs/note";

chromas().map((chroma) => pcset(chroma).intervals.map(transposeFrom("C")));