chord.rb

A chord object represents a chord defined as an unordered collection of tones (non-octaval). Mixes in the KeyContext module to provide optional key context on the chord.

Creating a Chord

Chords should be created by indexing the Chord class like an array, like so:

  Chord[symbol]

An alternative method of resolving a chord is to use the resolve method, though this is likely to become deprecated in the future when chord progression support/representation is added:

  Chord.resolve(symbol)

This resolves a specified chord symbol into a new chord object using data regarding chord symbol-to-chord relationships. symbol can be any standard jazz chord symbol representable as plain ASCII (unicode support for other symbols such as full-diminished circle in the works). Can be prefixed with a key.

Object Relationships

A chord object has the following associations, exposed by methods:

• symbols - Associated chord symbols.
• primary_symbol - Primary chord symbol.
• chord_scales - Chord-scale relationship objects. See ChordScale.
• modes - Direct access to associated scale modes through chord_scales.
• tones - Sequence of tones associated with the chord. See ToneSequence.
• voicings - Voicings associated with this chord.#

Example Usage

Creating Chords Without Key Context

  Chord['maj']
  Chord['min7'
  Chord['maj7#11']
  Chord['7#9']

Creating Chords With Key Context

  Chord['C7']
  Chord['Bbalt']
  Chord['Gbmaj7']

Getting Chord Notes

Use notes to retrieve a collection of notes, which actually delegates to +tones.notes+:

  Chord['C7'].notes
  # => ['C', 'E', 'G', 'Bb']

  Chord['Cmaj7#11'].notes
  # => ["C", "E", "G", "B", "F#"]

Correctly Interpets Theoretical Keys (not just pitches)

Note the 11 is correctly interpreted as E# and not enharmonic F here:

  Chord['Bmaj7#11'].notes
  # => ["B", "D#", "F#", "A#", "E#"]

Also correctly interpet tones off of enharmonic base keys:

  Chord['Gbmaj7'].notes
  # => ["Gb", "Bb", "Db", "F"]
  Chord['F#maj7'].notes
  # => ["F#", "A#", "C#", "E#"]

See Related Scales

  Chord['min7'].modes.names  # .names == .map(&:name)
  # => ['Dorian']
  Chord['min7'].modes[0].scale.name
  # => "Major"

  Chord['Amin7'].modes.names
  # => ['A Dorian']