Implement flat chords

Author: vhsenna

melodica_notes/chords.py

@@ -1,4 +1,4 @@
-from melodica_notes.scales import NOTES, scale
+from melodica_notes.scales import FLAT_NOTES, SHARP_NOTES, scale
 
 
 def minor(tonic_note: str) -> tuple[list[str], list[str]]:
@@ -51,9 +51,19 @@ def semitone(tonic_note: str, *, interval: int) -> str:
         >>> semitone('A', interval=-1)
         'G#'
     """
-    position = NOTES.index(tonic_note.upper()) + interval
+    if len(tonic_note) == 1:
+        tonic_note = tonic_note.upper()
+    else:
+        tonic_note = tonic_note[0].upper() + tonic_note[1].lower()
+
+    try:
+        position = SHARP_NOTES.index(tonic_note) + interval
+        notes = SHARP_NOTES
+    except ValueError:
+        position = FLAT_NOTES.index(tonic_note) + interval
+        notes = FLAT_NOTES
 
-    return NOTES[position % 12]
+    return notes[position % 12]
 
 
 def triad(tonic_note: str, scale_type: str) -> list[str]:

melodica_notes/scales.py

@@ -1,4 +1,6 @@
-NOTES = "C C# D D# E F F# G G# A A# B".split()
+NOTES = "C C# Db D D# Eb E F F# Gb G G# Ab A A# Bb B".split()
+SHARP_NOTES = "C C# D D# E F F# G G# A A# B".split()
+FLAT_NOTES = "C Db D Eb E F Gb G Ab A Bb B".split()
 SCALES = {"major": (0, 2, 4, 5, 7, 9, 11), "minor": (0, 2, 3, 5, 7, 8, 10)}
 
 
@@ -25,10 +27,16 @@ def scale(tonic_note: str, scale_type: str) -> dict[str, list[str]]:
         {'notes': ['A', 'B', 'C', 'D', 'E', 'F', 'G'], 'degrees': ['I', 'II', 'III', 'IV', 'V', 'VI', 'VII']}
     """
     tonic_note = tonic_note.upper()
+    notes = SHARP_NOTES
+
+    if len(tonic_note) > 1:
+        tonic_note = tonic_note[0] + tonic_note[1].lower()
+        if tonic_note[1] == "b":
+            notes = FLAT_NOTES
 
     try:
         intervals = SCALES[scale_type]
-        tonic_position = NOTES.index(tonic_note)
+        tonic_position = notes.index(tonic_note)
     except ValueError:
         raise ValueError(
             f"This musical note does not exist. Please use one of these: {NOTES}")
@@ -42,6 +50,6 @@ def scale(tonic_note: str, scale_type: str) -> dict[str, list[str]]:
 
     for interval in intervals:
         note = (tonic_position + interval) % 12
-        temp.append(NOTES[note])
+        temp.append(notes[note])
 
     return {"notes": temp, "degrees": ["I", "II", "III", "IV", "V", "VI", "VII"]}

tests/test_chord.py

@@ -11,7 +11,18 @@
         ("Cdim", ["C", "D#", "F#"]),
         ("C+", ["C", "E", "G#"]),
         ("Cm+", ["C", "D#", "G#"]),
+
         ("F#", ["F#", "A#", "C#"]),
+        ("F#m", ["F#", "A", "C#"]),
+        ("F#dim", ["F#", "A", "C"]),
+        ("F#+", ["F#", "A#", "D"]),
+        ("F#m+", ["F#", "A", "D"]),
+
+        ("Gb", ["Gb", "Bb", "Db"]),
+        ("Gbm", ["Gb", "A", "Db"]),
+        ("Gbdim", ["Gb", "A", "C"]),
+        ("Gb+", ["Gb", "Bb", "D"]),
+        ("Gbm+", ["Gb", "A", "D"]),
     ]
 )
 def test_chords_return_corresponding_notes(tonic_note, expected):

tests/test_scale.py

@@ -42,28 +42,28 @@ def test_raises_error_for_invalid_scale_type():
         ('C', 'major', ['C', 'D', 'E', 'F', 'G', 'A', 'B']),
         ('C#', 'major', ['C#', 'D#', 'F', 'F#', 'G#', 'A#', 'C']),
         ('D', 'major', ['D', 'E', 'F#', 'G', 'A', 'B', 'C#']),
-        ('D#', 'major', ['D#', 'F', 'G', 'G#', 'A#', 'C', 'D']),
+        ('Eb', 'major', ['Eb', 'F', 'G', 'Ab', 'Bb', 'C', 'D']),
         ('E', 'major', ['E', 'F#', 'G#', 'A', 'B', 'C#', 'D#']),
         ('F', 'major', ['F', 'G', 'A', 'A#', 'C', 'D', 'E']),
         ('F#', 'major', ['F#', 'G#', 'A#', 'B', 'C#', 'D#', 'F']),
         ('G', 'major', ['G', 'A', 'B', 'C', 'D', 'E', 'F#']),
-        ('G#', 'major', ['G#', 'A#', 'C', 'C#', 'D#', 'F', 'G']),
+        ('Ab', 'major', ['Ab', 'Bb', 'C', 'Db', 'Eb', 'F', 'G']),
         ('A', 'major', ['A', 'B', 'C#', 'D', 'E', 'F#', 'G#']),
-        ('A#', 'major', ['A#', 'C', 'D', 'D#', 'F', 'G', 'A']),
+        ('Bb', 'major', ['Bb', 'C', 'D', 'Eb', 'F', 'G', 'A']),
         ('B', 'major', ['B', 'C#', 'D#', 'E', 'F#', 'G#', 'A#']),
 
         # Minor Scales
         ('C', 'minor', ['C', 'D', 'D#', 'F', 'G', 'G#', 'A#']),
         ('C#', 'minor', ['C#', 'D#', 'E', 'F#', 'G#', 'A', 'B']),
         ('D', 'minor', ['D', 'E', 'F', 'G', 'A', 'A#', 'C']),
-        ('D#', 'minor', ['D#', 'F', 'F#', 'G#', 'A#', 'B', 'C#']),
+        ('Eb', 'minor', ['Eb', 'F', 'Gb', 'Ab', 'Bb', 'B', 'Db']),
         ('E', 'minor', ['E', 'F#', 'G', 'A', 'B', 'C', 'D']),
         ('F', 'minor', ['F', 'G', 'G#', 'A#', 'C', 'C#', 'D#']),
         ('F#', 'minor', ['F#', 'G#', 'A', 'B', 'C#', 'D', 'E']),
         ('G', 'minor', ['G', 'A', 'A#', 'C', 'D', 'D#', 'F']),
-        ('G#', 'minor', ['G#', 'A#', 'B', 'C#', 'D#', 'E', 'F#']),
+        ('Ab', 'minor', ['Ab', 'Bb', 'B', 'Db', 'Eb', 'E', 'Gb']),
         ('A', 'minor', ['A', 'B', 'C', 'D', 'E', 'F', 'G']),
-        ('A#', 'minor', ['A#', 'C', 'C#', 'D#', 'F', 'F#', 'G#']),
+        ('Bb', 'minor', ['Bb', 'C', 'Db', 'Eb', 'F', 'Gb', 'Ab']),
         ('B', 'minor', ['B', 'C#', 'D', 'E', 'F#', 'G', 'A']),
     ],
 )