Class: Coltrane::Theory::Scale

Inherits:
Object
  • Object
show all
Extended by:
ClassicScales, Forwardable
Defined in:
lib/coltrane/theory/scale.rb

Overview

Musical scale creation and manipulation

Direct Known Subclasses

DiatonicScale, GreekMode

Constant Summary

Constants included from ClassicScales

ClassicScales::SCALES

Instance Attribute Summary collapse

Instance Method Summary collapse

Methods included from ClassicScales

fetch, having_chords, having_notes, known_scales, major, minor, standard_scales

Constructor Details

#initialize(*relative_intervals, tone: 'C', mode: 1, name: nil, notes: nil) ⇒ Scale

Returns a new instance of Scale.



14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
 
# File 'lib/coltrane/theory/scale.rb', line 14

def initialize(*relative_intervals, tone: 'C',
               mode: 1,
               name: nil,
               notes: nil)
  @name = name
  if relative_intervals.any? && tone
    @tone              = Note[tone]
    relative_intervals = relative_intervals.rotate(mode - 1)
    @interval_sequence = IntervalSequence.new(
      relative_intervals: relative_intervals
    )
  elsif notes
    @notes             = NoteSet[*notes]
    @tone              = @notes.first
    ds                 = @notes.interval_sequence.relative_intervals
    @interval_sequence = IntervalSequence.new(relative_intervals: ds)
  else
    raise WrongKeywordsError,
          '[*relative_intervals, tone: "C", mode: 1] || [notes:]'
  end
end

Instance Attribute Details

#interval_sequence ⇒ Object (readonly)

Returns the value of attribute interval_sequence.



12
13
14
 
# File 'lib/coltrane/theory/scale.rb', line 12

def interval_sequence
  @interval_sequence
end

#tone ⇒ Object (readonly)

Returns the value of attribute tone.



12
13
14
 
# File 'lib/coltrane/theory/scale.rb', line 12

def tone
  @tone
end

Instance Method Details

#&(other) ⇒ Object

Raises:



88
89
90
91
 
# File 'lib/coltrane/theory/scale.rb', line 88

def &(other)
  raise HasNoNotesError unless other.respond_to?(:notes)
  notes & other
end

#==(other) ⇒ Object 



40
41
42
 
# File 'lib/coltrane/theory/scale.rb', line 40

def ==(other)
  id == other.id
end

#chords(size = 3..12) ⇒ Object Also known as: all_chords 



141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
 
# File 'lib/coltrane/theory/scale.rb', line 141

def chords(size = 3..12)
  size = (size..size) if size.is_a?(Integer)
  scale_rotations = interval_sequence.inversions
  ChordQuality.intervals_per_name.reduce([]) do |memo1, (qname, qintervals)|
    next memo1 unless size.include?(qintervals.size)
    memo1 + scale_rotations.each_with_index
                           .reduce([]) do |memo2, (rot, index)|
              if (rot & qintervals).size == qintervals.size
                memo2 + [Chord.new(root_note: degree(index + 1),
                                   quality: ChordQuality.new(name: qname))]
              else
                memo2
              end
            end
  end
end

#degree(d) ⇒ Object Also known as: []

Raises:



68
69
70
71
 
# File 'lib/coltrane/theory/scale.rb', line 68

def degree(d)
  raise WrongDegreeError, d if d < 1 || d > size
  tone + interval_sequence[d - 1].semitones
end

#degree_of_chord(chord) ⇒ Object 



79
80
81
82
 
# File 'lib/coltrane/theory/scale.rb', line 79

def degree_of_chord(chord)
  return if chords(chord.size).map(&:name).include?(chord.name)
  degree_of_note(chord.root_note)
end

#degree_of_note(note) ⇒ Object 



84
85
86
 
# File 'lib/coltrane/theory/scale.rb', line 84

def degree_of_note(note)
  notes.index(note)
end

#degrees ⇒ Object 



75
76
77
 
# File 'lib/coltrane/theory/scale.rb', line 75

def degrees
  (1..size)
end

#id ⇒ Object 



36
37
38
 
# File 'lib/coltrane/theory/scale.rb', line 36

def id
  [(name || @interval_sequence), tone.number]
end

#include_notes?(arg) ⇒ Boolean Also known as: include?

Returns:

  • (Boolean) 


93
94
95
96
 
# File 'lib/coltrane/theory/scale.rb', line 93

def include_notes?(arg)
  noteset = arg.is_a?(Note) ? NoteSet[arg] : arg
  (self & noteset).size == noteset.size
end

#interval(i) ⇒ Object 



104
105
106
 
# File 'lib/coltrane/theory/scale.rb', line 104

def interval(i)
  interval_sequence[(i - 1) % size]
end

#name ⇒ Object 



44
45
46
47
48
49
50
51
52
53
54
 
# File 'lib/coltrane/theory/scale.rb', line 44

def name
  @name ||= begin
    is = interval_sequence.relative_intervals
    (0...is.size).each do |i|
      if (scale_name = ClassicScales::SCALES.key(is.rotate(i)))
        return scale_name
      end
    end
    nil
  end
end

#notes ⇒ Object 



100
101
102
 
# File 'lib/coltrane/theory/scale.rb', line 100

def notes
  @notes ||= NoteSet[*degrees.map { |d| degree(d) }]
end

#pentads ⇒ Object 



133
134
135
 
# File 'lib/coltrane/theory/scale.rb', line 133

def pentads
  tertians(5)
end

#pretty_name ⇒ Object Also known as: full_name 



62
63
64
 
# File 'lib/coltrane/theory/scale.rb', line 62

def pretty_name
  "#{tone.pretty_name} #{name}"
end

#progression(*degrees) ⇒ Object 



137
138
139
 
# File 'lib/coltrane/theory/scale.rb', line 137

def progression(*degrees)
  Progression.new(self, degrees)
end

#sevenths ⇒ Object 



129
130
131
 
# File 'lib/coltrane/theory/scale.rb', line 129

def sevenths
  tertians(4)
end

#size ⇒ Object 



108
109
110
 
# File 'lib/coltrane/theory/scale.rb', line 108

def size
  interval_sequence.size
end

#tertians(n = 3) ⇒ Object 



112
113
114
115
116
117
118
119
120
121
122
123
 
# File 'lib/coltrane/theory/scale.rb', line 112

def tertians(n = 3)
  degrees.size.times.reduce([]) do |memo, d|
    ns = NoteSet[ *Array.new(n) { |i| notes[(d + (i * 2)) % size] } ]
    begin
      chord = Chord.new(notes: ns)
    rescue ChordNotFoundError
      memo
    else
      memo + [chord]
    end
  end
end

#triads ⇒ Object 



125
126
127
 
# File 'lib/coltrane/theory/scale.rb', line 125

def triads
  tertians(3)
end