Feature/intervals

README.md

@@ -78,14 +78,17 @@ True
 ## TODOs
 
 - ~~modes~~
-- ~~ midi note numbers (see https://musicinformationretrieval.com/midi_conversion_table.html and https://www.inspiredacoustics.com/en/MIDI_note_numbers_and_center_frequencies)~~
+- ~~midi note numbers (see https://musicinformationretrieval.com/midi_conversion_table.html and https://www.inspiredacoustics.com/en/MIDI_note_numbers_and_center_frequencies)~~
 - ~~init note from midi number~~
 - intervals 
   - addition and subtraction in scale
   - finding qualities of interval in scale (notation - https://en.wikipedia.org/wiki/Interval_(music)#Shorthand_notation, quality - https://en.wikipedia.org/wiki/Interval_(music)#Main_intervals)
-- add and subtract intervals within a context of a scale
-- chords with scales, chord names and notes they consist of (don't forget octaves and root notes) - https://en.wikipedia.org/wiki/List_of_chords
-- chords in given scales (similar to notes_in_scale method)
+  - check interval between two notes in scale
+- consonance and dissonance of intervals
+- chords with scales, chord names and notes they consist of (don't forget octaves and root notes) - https://en.wikipedia.org/wiki/List_of_chords - also https://en.wikipedia.org/wiki/Interval_(music)#Chord_qualities_and_interval_qualities
+- consonance and dissonance of scales
+- interval inversion
+- chords in given scales (similar to notes_in_scale method) 
 - chord transposing by adding or subtracting tonedeltas
 - init chord from given notes (check if matches any formula)
 - find nearest note to a given frequency

pyscales/primitives.py

@@ -100,6 +100,14 @@ def __eq__(self, other):
 
     def __add__(self, other):
 
+        from pyscales import IntervalInScale
+        from pyscales import Interval
+        if isinstance(other, IntervalInScale):
+            return other.add_to_note(self)
+        elif isinstance(other, Interval):
+            return other.add_to_note(self)
+
+        # assume other is ToneDelta
         # TODO: cache this somewhere
         notes_order = NoteArray(NoteArray.DEFAULT_NOTE_ORDER)
 
@@ -118,6 +126,9 @@ def __sub__(self, other):
 
         this_note_index = notes_order.index(self)
 
+        from pyscales import IntervalInScale
+
+        from pyscales import Interval
         if hasattr(other, 'semitones'):
 
             return notes_order[this_note_index-other.semitones]
@@ -128,7 +139,14 @@ def __sub__(self, other):
 
             return ToneDelta(this_note_index-other_not_index)
 
-        raise ValueError("Can only subtract ToneDelta or other Note")
+        elif isinstance(other, IntervalInScale):
+
+            return other.subtract_from_note(self)
+
+        elif isinstance(other, Interval):
+            return other.subtract_from_note(self)
+
+        raise ValueError("Can only subtract ToneDelta, IntervalInScale or other Note")
 
 
     def __str__(self):