Skip unpitched parts in to_abc(), fix 'pitch is undefined' — v0.41.3

Parts with only drum tones or rests are excluded from ABC output.
Chords correctly recognized as pitched content.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

CHANGELOG.md

@@ -2,6 +2,21 @@
 
 All notable changes to PyTheory are documented here.
 
+## 0.41.3
+
+- **Fix** — `to_abc()` now skips parts with only drum tones or rests (no pitched
+  notes), fixing "pitch is undefined" errors in abcjs. Chords are correctly
+  recognized as pitched content.
+
+## 0.41.2
+
+- **Auto bass clef** — `to_abc()` detects low-register parts (808, bass, timpani)
+  and assigns `clef=bass` automatically based on average note octave.
+
+## 0.41.1
+
+- **Fix** — `to_abc()` no longer crashes on parts containing drum tones.
+
 ## 0.41.0
 
 - **ABC notation export** — `Score.to_abc()` converts scores to ABC notation

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "pytheory"
-version = "0.41.0"
+version = "0.41.3"
 description = "Music Theory for Humans"
 readme = "README.md"
 license = "MIT"

pytheory/__init__.py

@@ -1,6 +1,6 @@
 """PyTheory: Music Theory for Humans."""
 
-__version__ = "0.41.0"
+__version__ = "0.41.3"
 
 from .tones import Tone, Interval
 from .systems import System, SYSTEMS, TET

pytheory/rhythm.py

@@ -4396,21 +4396,33 @@ class Score:
             f"L:1/{default_unit}",
         ]
 
-        # Collect voices: default notes first, then named parts (skip drums)
+        # Collect voices: default notes first, then named parts
+        # Skip drum parts and parts with no pitched notes
         voices: list[tuple[str, list]] = []
         if self.notes:
             voices.append(("default", self.notes))
         for name, part in self.parts.items():
             if part.is_drums:
                 continue
-            if part.notes:
-                voices.append((name, part.notes))
+            if not part.notes:
+                continue
+            # Skip parts that have no pitched tones (only drum tones / rests)
+            has_pitched = any(
+                n.tone is not None
+                and (hasattr(n.tone, "name") or hasattr(n.tone, "tones"))
+                for n in part.notes
+            )
+            if not has_pitched:
+                continue
+            voices.append((name, part.notes))
 
         multi = len(voices) > 1
 
         if multi:
-            for i, (vname, _) in enumerate(voices, 1):
-                lines.append(f"V:{i} name=\"{vname}\"")
+            for i, (vname, notes) in enumerate(voices, 1):
+                clef = self._guess_clef(notes)
+                clef_str = f" clef={clef}" if clef != "treble" else ""
+                lines.append(f"V:{i} name=\"{vname}\"{clef_str}")
             lines.append(f"K:{key}")
             for i, (_, notes) in enumerate(voices, 1):
                 lines.append(f"V:{i}")
@@ -4436,12 +4448,36 @@ class Score:
             + ");\n</script>\n</body></html>\n"
         )
 
+    @staticmethod
+    def _guess_clef(notes):
+        """Return 'bass' if most pitched notes are below C4, else 'treble'."""
+        octaves = []
+        for note in notes:
+            tone = note.tone
+            if tone is None or not hasattr(tone, "octave"):
+                continue
+            if hasattr(tone, "tones"):
+                # Chord — use average of chord tones
+                for t in tone.tones:
+                    if hasattr(t, "octave") and t.octave is not None:
+                        octaves.append(t.octave)
+            elif tone.octave is not None:
+                octaves.append(tone.octave)
+        if not octaves:
+            return "treble"
+        avg = sum(octaves) / len(octaves)
+        return "bass" if avg < 4 else "treble"
+
     @staticmethod
     def _tone_to_abc(tone, default_unit):
         """Convert a single Tone to an ABC note string."""
         if tone is None:
             return "z"
 
+        # Skip drum tones — they don't have pitched names
+        if not hasattr(tone, "name") or not hasattr(tone, "octave"):
+            return "z"
+
         name = tone.name          # e.g. "C", "C#", "Bb"
         octave = tone.octave if tone.octave is not None else 4
 

uv.lock

@@ -690,7 +690,7 @@ wheels = [
 
 [[package]]
 name = "pytheory"
-version = "0.41.0"
+version = "0.41.3"
 source = { editable = "." }
 dependencies = [
     { name = "rich" },