Class: MTK::Groups::Chord

Inherits:
Melody
  • Object
show all
Defined in:
lib/mtk/groups/chord.rb

Overview

A sorted collection of distinct Pitches.

The “vertical” (simultaneous) pitch collection.

See Also:

Instance Attribute Summary

Attributes inherited from Melody

#pitches

Instance Method Summary collapse

Methods inherited from Melody

#==, #=~, #elements, from_a, from_pitch_classes, #pitch_classes, #to_pitch_class_set, #to_s

Methods included from PitchCollection

#invert, #transpose

Methods included from Collection

#==, #[], #clone, #concat, #each, #empty?, #enumerable_map, #first, #last, #map, #partition, #permute, #repeat, #reverse, #rotate, #size, #to_a

Constructor Details

#initialize(pitches) ⇒ Chord

Note:

duplicate pitches will be removed. See #Melody if you want to maintain duplicates.

Returns a new instance of Chord.

Parameters:

  • pitches (#to_a) —

    the collection of pitches



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# File 'lib/mtk/groups/chord.rb', line 16

def initialize(pitches)
  pitches = pitches.to_a.clone
  pitches.uniq!
  pitches.sort!
  @pitches = pitches.freeze
end

Instance Method Details

#inversion(number) ⇒ Object

Generate a chord inversion (positive numbers move the lowest notes up an octave, negative moves the highest notes down)



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# File 'lib/mtk/groups/chord.rb', line 24

def inversion(number)
  number = number.to_i
  pitch_set = Array.new(@pitches.uniq.sort)
  if number > 0
    number.times do |count|
      index = count % pitch_set.length
      pitch_set[index] += 12
    end
  else
    number.abs.times do |count|
      index = -(count + 1) % pitch_set.length # count from -1 downward to go backwards through the list starting at the end
      pitch_set[index] -= 12
    end
  end
  self.class.new pitch_set.sort
end

#nearest(pitch_class) ⇒ Object

Transpose the chord so that it’s lowest pitch is the given pitch class.



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# File 'lib/mtk/groups/chord.rb', line 42

def nearest(pitch_class)
  self.transpose @pitches.first.pitch_class.distance_to(pitch_class)
end