Fix Playability

generator/hand_position.py

@@ -0,0 +1,52 @@
+"""Four-fret hand windows shared by chord and single-note placement.
+
+This describes playable regions, not an anatomical fingering solver. Chord
+and single tones may occupy any frets within the window. Only shifting the
+window is movement. Actual sounded-note limits remain in fretboard.py.
+"""
+import functools
+import typing
+
+import generator.fretboard
+
+VERSION = 'hand-window-2'
+
+class Motion(typing.NamedTuple):
+  shift: int = 0
+  fingers: int = 0
+  strings: int = 0
+  @property
+  def ergonomics(self):
+    return self.fingers + self.strings
+
+def base(shape):
+  return min((p.fret for p in shape), default=0)
+
+@functools.lru_cache(maxsize=4096)
+def regions(shape):
+  if not shape:
+    return tuple([0])
+  return tuple(range(max(1, max(p.fret for p in shape) - 3), min(base(shape), generator.fretboard.MAX_ANCHOR_FRET) + 1))
+
+@functools.lru_cache(maxsize=32768)
+def motion(previous, current, old_hand, hand, acoustic=False):
+  if not previous or not current:
+    return Motion()
+  if len(previous) == len(current) == 1:
+    pairs = ((previous[0], current[0]),)
+    unmatched = 0
+  else:
+
+    def voices(shape):
+      return {('bass' if acoustic and p.string_number in (5, 6) else p.string_number): p for p in shape}
+
+    a, b = voices(previous), voices(current)
+    pairs = tuple((a[s], b[s]) for s in a.keys() & b.keys())
+    unmatched = len(a.keys() ^ b.keys())
+  return Motion(abs(hand - old_hand),
+    unmatched + sum(abs((a.fret - old_hand) - (b.fret - hand)) for a, b in pairs),
+    sum(abs(a.string_number - b.string_number) for a, b in pairs))
+
+def summary(shifts):
+  shifts = tuple(shifts)
+  return {'total_travel': sum(shifts), 'shift_count': sum(s > 0 for s in shifts), 'largest_shift': max(shifts, default=0)}