Add triads and note names

src/MusicTheory.jl

@@ -15,9 +15,13 @@ export major_scale, natural_minor_scale, melodic_minor_scale, harmonic_minor_sca
 
 export Chord
 
+export make_triad, is_triad
+
 
 include("notes.jl")
+include("note_names.jl")
 include("intervals.jl")
 include("scales.jl")
 include("chords.jl")
+include("triads.jl")
 end

src/chords.jl

@@ -0,0 +1,12 @@
+
+
+# const Chord{T <: Union{PitchClass, Pitch}} = Set{T}
+
+struct Chord{T <: Union{PitchClass, Pitch}}
+    notes::Set{T}
+end
+
+Chord(notes::T...) where {T <: Union{PitchClass, Pitch}} = Chord{T}(Set(notes))
+
+
+Base.length(chord::Chord) = length(chord.notes)

src/note_names.jl

@@ -0,0 +1,44 @@
+
+module NoteNames
+
+using MusicTheory:
+    C, D, E, F, G, A, B,
+    C♮, D♮, E♮, F♮, G♮, A♮, B♮,
+    C♯, D♯, E♯, F♯, G♯, A♯, B♯,
+    C♭, D♭, E♭, F♭, G♭, A♭, B♭,
+    C𝄫, D𝄫, E𝄫, F𝄫, G𝄫, A𝄫, B𝄫,
+    C𝄪, D𝄪, E𝄪, F𝄪, G𝄪, A𝄪, B𝄪
+
+export
+    C, D, E, F, G, A, B,
+    C♮, D♮, E♮, F♮, G♮, A♮, B♮,
+    C♯, D♯, E♯, F♯, G♯, A♯, B♯,
+    C♭, D♭, E♭, F♭, G♭, A♭, B♭,
+    C𝄫, D𝄫, E𝄫, F𝄫, G𝄫, A𝄫, B𝄫,
+    C𝄪, D𝄪, E𝄪, F𝄪, G𝄪, A𝄪, B𝄪,
+    middle_C
+
+const middle_C = C[4]
+
+end
+
+
+module AllNoteNames
+
+using MusicTheory: note_names, Pitch, PitchClass, Accidental
+
+using MusicTheory.NoteNames
+
+for note in note_names, octave in 0:9
+    name = Symbol(note, octave)
+    @eval $(name) = Pitch(PitchClass($(Meta.quot(note))), $(octave))
+    @eval export $(name)
+
+    for accidental in instances(Accidental)
+        name = Symbol(note, accidental, octave)
+        @eval $(name) = Pitch(PitchClass($(Meta.quot(note)), $(accidental)), $(octave))
+        @eval export $(name)
+    end
+end
+
+end

src/notes.jl

@@ -83,24 +83,8 @@ Base.isless(n1::PitchClass, n2::PitchClass) = semitone(n1) < semitone(n2)
 Base.isless(n1::Pitch, n2::Pitch) = semitone(n1) < semitone(n2)
 
 
-
-
 # define Julia objects for pitch classes:
 
-module NoteNames
-
-using MusicTheory
-using MusicTheory: note_names
-
-export
-    C, D, E, F, G, A, B,
-    C♮, D♮, E♮, F♮, G♮, A♮, B♮,
-    C♯, D♯, E♯, F♯, G♯, A♯, B♯,
-    C♭, D♭, E♭, F♭, G♭, A♭, B♭,
-    C𝄫, D𝄫, E𝄫, F𝄫, G𝄫, A𝄫, B𝄫,
-    C𝄪, D𝄪, E𝄪, F𝄪, G𝄪, A𝄪, B𝄪,
-    middle_C
-
 for name in note_names, accidental in instances(Accidental)
     note = Symbol(name, accidental)
 
@@ -111,7 +95,3 @@ for name in note_names, accidental in instances(Accidental)
     end
 end
 
-const middle_C = C[4]
-
-
-end

src/triads.jl

@@ -0,0 +1,42 @@
+function make_triad(scale::Scale, root::Pitch)
+
+    !haskey(scale.steps, PitchClass(root)) && error("$root not in scale")
+
+    triad_notes = [root]
+
+    current, next = iterate(scale, root)
+    current, next = iterate(scale, next)
+
+    push!(triad_notes, next)
+
+    current, next = iterate(scale, next)
+    current, next = iterate(scale, next)
+
+    push!(triad_notes, next)
+
+    return Chord(triad_notes...)
+end
+
+
+function find_intervals(chord)
+    notes = sort(collect(chord.notes))
+    # return [interval(n1, n2) for n1 in notes for n2 in notes if n1 < n2]
+    return [Interval(notes[1], notes[2]), Interval(notes[1], notes[3])]
+end
+
+
+function is_triad(chord::Chord{PitchClass})
+    length(chord) != 3 && return false
+
+    # put them in the same octave:
+    pitches = [Pitch(n, 4) for n in chord.notes]
+
+    intervals = find_intervals(Chord(pitches...)) |> collect
+    numbers = (intervals[1].number, intervals[2].number)
+
+    return numbers ∈ ( (3, 5), (3, 6), (4, 6) )
+end
+
+is_triad(chord::Chord{Pitch}) = is_triad(Chord(PitchClass.(chord.notes)...))
+
+is_triad(notes...) = is_triad(Chord(notes...))

test/runtests.jl

@@ -4,3 +4,4 @@ using Test
 include("notes.jl")
 include("intervals.jl")
 include("scales.jl")
+include("triads.jl")

test/triads.jl

@@ -0,0 +1,13 @@
+@testset "Triads" begin
+    @test is_triad(Chord(B, D, F))
+    @test is_triad(B[4], D[7], F[1])
+
+    @test !is_triad(Chord(A, B, C))
+    @test !is_triad(A, B, C)
+end
+
+@testset "Triads with names" begin
+    using MusicTheory.AllNoteNames
+
+    @test is_triad(C4, E5, A8)
+end