Compare ArpeggioMarkSpanners (ArpeggioMarks come for free, since they are in gnote.expressions).

Note that this only works with my music21 arpeggio additions (music21 v8.0.0a9), and if you care about Humdrum, my converter21 arpeggio additions (converter21 v1.3.1).
If you have an earlier version of music21 (or converter21), arpeggio differences will simply not be found.

Author: gregchapman-dev

build_dist.commands

@@ -1,6 +1,8 @@
 # Clean up previous stuff:
 rm -r __pycache__
 rm -r musicdiff/__pycache__
+rm -r tests/__pycache__
+rm -r musicdiff.egg-info
 rm -r dist build
 
 # Build dist and wheel:

musicdiff/annotation.py

@@ -263,7 +263,9 @@ def __init__(self, extra: m21.base.Music21Object, measure: m21.stream.Measure, s
         self.extra = extra.id
         self.offset: float
         self.duration: float
+        self.numNotes: int = 1
         if isinstance(extra, m21.spanner.Spanner):
+            self.numNotes = len(extra)
             firstNote: m21.note.GeneralNote = extra.getFirst()
             lastNote: m21.note.GeneralNote = extra.getLast()
             self.offset = float(firstNote.getOffsetInHierarchy(measure))
@@ -301,6 +303,8 @@ def __str__(self):
             str: the compared representation of the AnnExtra. Does not consider music21 id.
         """
         string = f'{self.content},off={self.offset},dur={self.duration}'
+        if self.numNotes != 1:
+            string += f',numNotes={self.numNotes}'
         # and then any style fields
         for k, v in self.styledict.items():
             string += f",{k}={v}"

musicdiff/m21utils.py

@@ -424,14 +424,20 @@ def get_extras(measure: m21.stream.Measure, spannerBundle: m21.spanner.SpannerBu
             if M21Utils.extra_to_string(el) != '':
                 output.append(el)
 
-        # we must add any Crescendo/Diminuendo spanners that start on GeneralNotes in this measure
+        # Add any ArpeggioMarkSpanners/Crescendos/Diminuendos that start
+        # on GeneralNotes in this measure
+        if hasattr(m21.expressions, 'ArpeggioMarkSpanner'):
+            spanner_types = (m21.expressions.ArpeggioMarkSpanner, m21.dynamics.DynamicWedge)
+        else:
+            spanner_types = (m21.dynamics.DynamicWedge,)
+
         for gn in measure.recurse().getElementsByClass(m21.note.GeneralNote):
-            dwList: List[m21.dynamics.DynamicWedge] = gn.getSpannerSites(m21.dynamics.DynamicWedge)
-            for dw in dwList:
-                if dw not in spannerBundle:
+            spannerList: List[m21.spanner.Spanner] = gn.getSpannerSites(spanner_types)
+            for sp in spannerList:
+                if sp not in spannerBundle:
                     continue
-                if dw.isFirst(gn):
-                    output.append(dw)
+                if sp.isFirst(gn):
+                    output.append(sp)
 
         return output
 
@@ -691,6 +697,17 @@ def dynwedge_to_string(dynwedge: m21.dynamics.DynamicWedge) -> str:
             output = 'wedge'
         return f'DY:{output}'
 
+    @staticmethod
+    def arpeggiomark_to_string(
+        arp: m21.expressions.Expression) -> str:
+        if hasattr(m21.expressions, 'ArpeggioMark'):
+            if isinstance(arp, m21.expressions.ArpeggioMark):
+                return f'ARP:{arp.type}'
+        if hasattr(m21.expressions, 'ArpeggioMarkSpanner'):
+            if isinstance(arp, m21.expressions.ArpeggioMarkSpanner):
+                return f'ARPS:{arp.type}:len={len(arp)}'
+        return ''
+
     @staticmethod
     def extra_to_string(extra: m21.base.Music21Object) -> str:
         if isinstance(extra, (m21.key.Key, m21.key.KeySignature)):
@@ -709,6 +726,10 @@ def extra_to_string(extra: m21.base.Music21Object) -> str:
             return M21Utils.tempo_to_string(extra)
         if isinstance(extra, m21.bar.Barline):
             return M21Utils.barline_to_string(extra)
+        if (hasattr(m21.expressions, 'ArpeggioMark')
+                and hasattr(m21.expressions, 'ArpeggioMarkSpanner')):
+            if isinstance(extra, (m21.expressions.ArpeggioMark, m21.expressions.ArpeggioMarkSpanner)):
+                return M21Utils.arpeggiomark_to_string(extra)
 
         print(f'Unexpected extra: {extra.classes[0]}', file=sys.stderr)
         return ''