added support for N chords

Author: andreamust

README.md

@@ -56,7 +56,7 @@ The main functionality of the Harte Library is an extension of the *Chord Module
 This is possible by means of the class __Harte__, which accepts as input a chord expressed in Harte Notation and allows all properties and methods of the Chord module of music21 to be used:
 
 ```python
-from harte.harte_core import Harte
+from harte.harte import Harte
 
 chord = Harte('C#:maj7(b6)/b3')
 
@@ -75,7 +75,7 @@ In addition, the library implements new methods specific to Harte notation, incl
 * __prettify__: breaks the chord into its components and recomposes it by choosing the most summarised shorthand, if possible.
 
 ```python
-from harte.harte_core import Harte
+from harte.harte import Harte
 
 chord = Harte('D:(b3,5,7,9)')
 

harte/harte_core.py renamed to harte/harte.py

@@ -38,7 +38,13 @@ def __init__(self, chord: str, **keywords):
                 f'The input chord {chord} is not a valid Harte chord') \
                 from name_error
 
-        if "root" in parsed_chord:
+        if self.chord == 'N':
+            self._root = self._bass = self._degrees = self._shorthand = None
+            self._all_degrees = []
+            super().__init__(self._all_degrees)
+            return
+
+        elif "root" in parsed_chord:
             # chord is not empty
             # retrieve information from the parsed chord
             self._root = parsed_chord['root']
@@ -270,6 +276,7 @@ def __str__(self):
     # test utilities
     test_chord = Harte('N')
     root = test_chord.get_root()
+    print(test_chord.pitchNames)
     print(test_chord.fullName)
     print(test_chord.commonName)
     print(test_chord.inversion())

test/test_harte.py

@@ -8,7 +8,7 @@
 
 import pytest
 
-from harte.harte_core import Harte
+from harte.harte import Harte
 
 # load a dict of chords frequencies extracted from ChoCo [1]
 # to test coverage of a big set of chords
@@ -37,7 +37,8 @@ def test_coverage(chord: str):
                           ("C:maj", ["P5", "M3"]),
                           ("C:min", ["P5", "m3"]),
                           ("C:dim", ["d5", "m3"]),
-                          ("C:aug", ["A5", "M3"]), ])
+                          ("C:aug", ["A5", "M3"]),
+                          ("N", [])])
 def test_interval_extraction(chord: str, intervals: List[str]):
     """
     Test that the annotateIntervals of music21 correctly works in extracting