Class Chord
In: app/models/chord.rb
Parent: ActiveRecord::Base

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']

Methods

cache   resolve   symbols_list  

Included Modules

KeyContext

External Aliases

resolve -> []

Public Class methods

cache(conditions = [])

Retreives Fully-Cached Array

[Source]

     # File app/models/chord.rb, line 139
139:         def self.cache(conditions = [])
140:                 self.find(:all, :include => [:tones, :symbols], :conditions => conditions) # Rails 2.0 Already Caches!
141:         end
resolve(symbol)

Resolves a chord symbol into a chord. Implementation is somewhat flakey due to the potential ambiguities arising from specifying key and symbols together.

[Source]

     # File app/models/chord.rb, line 106
106:                 def resolve(symbol)
107:                         in_key = nil
108:                   
109:                         return nil if symbol.nil?
110:                         
111:                         Key.cache.each do |k|
112:                                 if symbol.starts_with?(k.name)
113:                                         in_key = k
114:                                         symbol.sub!(k.name, '').strip
115:                                         break
116:                                 end
117:                         end
118:                         
119:                         chord_symbol = ChordSymbol[symbol]
120:                         
121:                         # Perhaps the matched key was really part of the name of the chord, try that:
122:                         if chord_symbol.nil? && !in_key.nil?
123:                                 symbol = in_key.name + symbol
124:                                 chord_symbol = ChordSymbol[symbol]
125:                         end
126:                         
127:                         # If still not found, must be invalid:
128:                         return nil if chord_symbol.nil?
129:                         
130:                         chord = chord_symbol.chord
131:                         chord.key = in_key unless in_key.nil?
132:                         chord
133:                 end

Public Instance methods

symbols_list()

[Source]

    # File app/models/chord.rb, line 97
97:         def symbols_list
98:                 self.symbols.map {|s| s.name }.join(', ')
99:         end

[Validate]