Clean up code: remove unused imports, variables, and functions

- Remove duplicate 'permutations' import
- Remove unused 'choice' import
- Remove unused '_check_melodic_threshold' function
- Remove unused 'sorted_permutation' variable
- Update outdated comments
- Simplify _initialize_chords return value

compact_sets.py

@@ -13,10 +13,10 @@ Mathematical foundations:
 
 from __future__ import annotations
 from fractions import Fraction
-from itertools import combinations, permutations, permutations
+from itertools import combinations, permutations
 from math import prod, log
 from operator import add
-from random import choice, choices, seed
+from random import choices, seed
 from typing import Iterator
 
 import networkx as nx
@@ -711,31 +711,6 @@ class HarmonicSpace:
                 diff_count += 1
         return diff_count == 1
 
-    def _check_melodic_threshold(
-        self,
-        movements: dict,
-        threshold_cents: float,
-    ) -> bool:
-        """Check if changing pitch movements stay within melodic threshold.
-
-        Args:
-            movements: Dict mapping source pitch -> {destination, cent_difference}
-            threshold_cents: Maximum allowed movement in cents
-
-        Returns:
-            True if all movements are within threshold.
-            Common pitches (0 cents) always pass.
-            Changing pitches must have cent_difference <= threshold.
-        """
-        for src, data in movements.items():
-            cents = data["cent_difference"]
-            # Common pitches have 0 cent difference - always pass
-            # Changing pitches: check if movement is within threshold
-            if cents > threshold_cents:
-                return False
-
-        return True
-
     def _invert_transposition(self, trans: Pitch) -> Pitch:
         """Invert a transposition."""
         return Pitch(tuple(-t for t in trans.hs_array), self.dims)
@@ -773,21 +748,16 @@ class PathFinder:
             weights_config = self._default_weights_config()
 
         # Initialize
-        chords_data = self._initialize_chords(start_chord)
-        if not chords_data or not chords_data[0]:
+        chord = self._initialize_chords(start_chord)
+        if not chord or chord[0] is None or len(self.graph.nodes()) == 0:
             return []
 
-        chord_pair = chords_data[0]
-        original_chord = chord_pair[0] if chord_pair else None
-        sorted_permutation = chords_data[1] if len(chords_data) > 1 else None
-
-        if original_chord is None or len(self.graph.nodes()) == 0:
-            return []
+        original_chord = chord[0]
 
         # The graph node to use for edge lookup (original chord from harmonic space)
         graph_node = original_chord
 
-        # The output chord is the original (unsorted) for testing voice crossing detection
+        # The output chord for path
         output_chord = original_chord
 
         path = [output_chord]
@@ -799,7 +769,7 @@ class PathFinder:
         cumulative_trans = Pitch(tuple(0 for _ in range(len(dims))), dims)
 
         # Track voice mapping: voice_map[i] = which original voice is at position i
-        # Use identity since we're not sorting output
+        # Start with identity
         num_voices = len(output_chord.pitches)
         voice_map = list(range(num_voices))
 
@@ -854,7 +824,6 @@ class PathFinder:
 
             # Reorder pitches according to voice mapping
             # voice_map[i] = which original voice is at position i
-            # With voice_map initialized to sorted_permutation, output stays in bass-to-soprano order
             reordered_pitches = tuple(
                 transposed.pitches[voice_map[i]] for i in range(num_voices)
             )
@@ -874,15 +843,10 @@ class PathFinder:
         """Initialize chord sequence.
 
         Returns:
-            Tuple of ((original_chord, transposed_chord), sorted_permutation)
-            where sorted_permutation[i] = which original voice index is at position i in sorted order
+            Tuple of (original_chord,)
         """
         if start_chord is not None:
-            # Compute permutation from original to sorted
-            pitches = list(start_chord.pitches)
-            sorted_pitches = sorted(pitches, key=lambda p: p.to_fraction())
-            sorted_permutation = [pitches.index(p) for p in sorted_pitches]
-            return ((start_chord, start_chord), sorted_permutation)
+            return (start_chord,)
 
         # Random start - try multiple times to find a chord with valid edges (respecting voice crossing)
         nodes = list(self.graph.nodes())
@@ -909,19 +873,12 @@ class PathFinder:
 
                 if nonzero > 0:
                     # Found a valid starting chord
-                    pitches = list(chord.pitches)
-                    sorted_pitches = sorted(pitches, key=lambda p: p.to_fraction())
-                    sorted_permutation = [pitches.index(p) for p in sorted_pitches]
-                    return ((chord, chord), sorted_permutation)
+                    return (chord,)
 
             # Fall back to first node if none found
-            chord = nodes[0]
-            pitches = list(chord.pitches)
-            sorted_pitches = sorted(pitches, key=lambda p: p.to_fraction())
-            sorted_permutation = [pitches.index(p) for p in sorted_pitches]
-            return ((chord, chord), sorted_permutation)
+            return (nodes[0],)
 
-        return ((), None)
+        return (None,)
 
     def _default_weights_config(self) -> dict:
         """Default weights configuration."""