Class: HeadMusic::PitchClass

Inherits:
Object
  • Object
show all
Includes:
Comparable
Defined in:
lib/head_music/pitch_class.rb

Overview

A pitch class is a set of pitches separated by octaves.

Constant Summary collapse

SHARP_SPELLINGS = 
%w[C C♯ D D♯ E F F♯ G G♯ A A♯ B].freeze
FLAT_SPELLINGS = 
%w[C D♭ D E♭ E F G♭ G A♭ A B♭ B].freeze
FLATTER_SPELLINGS = 
%w[C D♭ D E♭ F♭ F G♭ G A♭ A B♭ C♭].freeze
INTEGER_NOTATION = 
%w[0 1 2 3 4 5 6 7 8 9 t e].freeze

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(pitch_class_or_midi_number) ⇒ PitchClass

Returns a new instance of PitchClass.



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# File 'lib/head_music/pitch_class.rb', line 26

def initialize(pitch_class_or_midi_number)
  @number = pitch_class_or_midi_number.to_i % 12
end

Instance Attribute Details

#number ⇒ Object (readonly)

Returns the value of attribute number.



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# File 'lib/head_music/pitch_class.rb', line 5

def number
  @number
end

#spelling ⇒ Object (readonly)

Returns the value of attribute spelling.



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# File 'lib/head_music/pitch_class.rb', line 5

def spelling
  @spelling
end

Class Method Details

.get(identifier) ⇒ Object Also known as: [] 



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# File 'lib/head_music/pitch_class.rb', line 12

def self.get(identifier)
  @pitch_classes ||= {}
  if HeadMusic::Spelling.matching_string(identifier)
    spelling = HeadMusic::Spelling.get(identifier)
    number = spelling.pitch_class.to_i
  end
  number ||= identifier.to_i % 12
  @pitch_classes[number] ||= new(number)
end

Instance Method Details

#+(other) ⇒ Object

Pass in the number of semitones



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# File 'lib/head_music/pitch_class.rb', line 61

def +(other)
  HeadMusic::PitchClass.get(to_i + other.to_i)
end

#-(other) ⇒ Object

Pass in the number of semitones



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# File 'lib/head_music/pitch_class.rb', line 66

def -(other)
  HeadMusic::PitchClass.get(to_i - other.to_i)
end

#<=>(other) ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 75

def <=>(other)
  to_i <=> other.to_i
end

#==(other) ⇒ Object Also known as: enharmonic? 



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# File 'lib/head_music/pitch_class.rb', line 70

def ==(other)
  to_i == other.to_i
end

#black_key? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/pitch_class.rb', line 93

def black_key?
  !white_key?
end

#flat_spelling ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 42

def flat_spelling
  FLAT_SPELLINGS[number]
end

#flatter_spelling ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 46

def flatter_spelling
  FLATTER_SPELLINGS[number]
end

#intervals_to(other) ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 79

def intervals_to(other)
  delta = other.to_i - to_i
  inverse = delta.positive? ? delta - 12 : delta + 12
  [delta, inverse].sort_by(&:abs).map { |interval| HeadMusic::ChromaticInterval.get(interval) }
end

#sharp_spelling ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 38

def sharp_spelling
  SHARP_SPELLINGS[number]
end

#smallest_interval_to(other) ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 85

def smallest_interval_to(other)
  intervals_to(other).first
end

#smart_spelling(max_sharps_in_major_key_signature: 6) ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 50

def smart_spelling(max_sharps_in_major_key_signature: 6)
  sharp_key = HeadMusic::KeySignature.get(sharp_spelling)
  return HeadMusic::Spelling.get(sharp_spelling) if sharp_key.num_sharps <= max_sharps_in_major_key_signature

  flat_key = HeadMusic::KeySignature.get(flat_spelling)
  return HeadMusic::Spelling.get(flat_spelling) if flat_key.num_sharps <= max_sharps_in_major_key_signature

  HeadMusic::Spelling.get(flatter_spelling)
end

#to_i ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 30

def to_i
  number
end

#to_integer_notation ⇒ Object 



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# File 'lib/head_music/pitch_class.rb', line 34

def to_integer_notation
  INTEGER_NOTATION[number]
end

#white_key? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/head_music/pitch_class.rb', line 89

def white_key?
  [0, 2, 4, 5, 7, 9, 11].include?(number)
end