feat(presets): 6-colour contrast derivation fns

sound_algo/data_only/matrix_presets/patterns.py

@@ -39,6 +39,54 @@ def _mel(pairs):
     return [None if p is None else (int(p[0]), round(float(p[1]), 2)) for p in pairs]
 
 
+_DRUM_VELS = (0.30, 0.50, 0.80, 1.0)
+
+
+def _dhit(v):
+    return None if v == 0.0 else (0, round(v, 2))
+
+
+def derive_drum_colors(base):
+    """Colours 2-6 from a 16-step drum base (None | (0, vel))."""
+    n = len(base)
+    busier = [base[i] if base[i] is not None else (_dhit(0.30) if i % 4 == 2 else None)
+              for i in range(n)]
+    broken = base[-1:] + base[:-1]                       # rotate right 1: same count, displaced
+    double = [base[i] if base[i] is not None else (_dhit(0.80) if i % 2 == 0 else None)
+              for i in range(n)]
+    sparse = [base[i] if (base[i] is not None and ((base[i][1] >= 1.0) or i % 4 == 0)) else None
+              for i in range(n)]
+    fill = list(base)
+    for k, v in enumerate((0.80, 0.80, 1.0, 1.0)):
+        fill[n - 4 + k] = _dhit(v)
+    return [busier, broken, double, sparse, fill]
+
+
+def derive_mel_colors(base):
+    """Colours 2-6 from a 16-step melodic base (None | (degree, vel))."""
+    n = len(base)
+    actives = [base[i][0] for i in range(n) if base[i] is not None]
+    last_deg = actives[-1] if actives else 0
+
+    def prev_deg(i):
+        for j in range(i, -1, -1):
+            if base[j] is not None:
+                return base[j][0]
+        return last_deg
+
+    busier = [base[i] if base[i] is not None else ((prev_deg(i), 0.5) if i % 4 == 2 else None)
+              for i in range(n)]
+    broken = [((base[i][0] + 7, base[i][1]) if (base[i] is not None and i % 4 == 0) else base[i])
+              for i in range(n)]
+    double = [base[i] if base[i] is not None else ((prev_deg(i), 0.6) if i % 2 == 0 else None)
+              for i in range(n)]
+    sparse = [base[i] if (base[i] is not None and i % 4 == 0) else None for i in range(n)]
+    fill = list(base)
+    for k in range(4):
+        fill[n - 4 + k] = (last_deg + k, round(0.6 + 0.1 * k, 2))
+    return [busier, broken, double, sparse, fill]
+
+
 N = None
 
 # =============================================================================

sound_algo/data_only/matrix_presets/test_contrast.py

@@ -0,0 +1,44 @@
+"""Standalone test for the 6-colour contrast derivation.
+Run: cd sound_algo/data_only/matrix_presets && uv run python test_contrast.py
+Prints TEST PASS / TEST FAIL; exits non-zero on failure."""
+import sys, os
+sys.path.insert(0, os.path.dirname(os.path.abspath(__file__)))
+from patterns import derive_drum_colors, derive_mel_colors, _rhythm, _mel
+
+ok = True
+def check(c, m):
+    global ok
+    if not c: ok = False; print("FAIL:", m)
+
+def dens(p): return sum(1 for s in p if s is not None)
+
+# --- drums ---
+base = _rhythm("X...x...X...x...")          # 4 hits
+c2, c3, c4, c5, c6 = derive_drum_colors(base)
+check(all(len(c) == 16 for c in (c2,c3,c4,c5,c6)), "drum colours 16 steps")
+check(dens(c2) >= dens(base), "busier >= base")
+check(dens(c4) >= dens(base), "double >= base")
+check(dens(c5) <= dens(base), "sparse <= base")
+check(dens(c3) == dens(base), "broken keeps hit count")
+check([i for i in range(16) if (c3[i] is not None) != (base[i] is not None)] != [], "broken displaces")
+check(all(c6[i] is not None for i in range(12, 16)), "fill last 4 active")
+# velocities legal
+legal = {0.30, 0.50, 0.80, 1.0}
+for c in (c2, c3, c4, c5, c6):
+    check(all(s is None or s[1] in legal for s in c), "drum vel legal")
+# determinism
+check(derive_drum_colors(base) == derive_drum_colors(base), "drum deterministic")
+
+# --- mel ---
+mbase = _mel([(0,0.8),None,(3,0.6),None,(7,0.7),None,None,None,
+              (5,0.6),None,(3,0.6),None,(0,0.8),None,None,None])
+m2, m3, m4, m5, m6 = derive_mel_colors(mbase)
+check(all(len(c) == 16 for c in (m2,m3,m4,m5,m6)), "mel colours 16 steps")
+check(dens(m4) >= dens(mbase), "mel double >= base")
+check(dens(m5) <= dens(mbase), "mel sparse <= base")
+check(all((s is None) or (isinstance(s[0], int) and isinstance(s[1], float)) for s in m4), "mel step shape")
+check(all(m6[i] is not None for i in range(12, 16)), "mel fill last 4 active")
+check(derive_mel_colors(mbase) == derive_mel_colors(mbase), "mel deterministic")
+
+print("TEST PASS" if ok else "TEST FAIL")
+sys.exit(0 if ok else 1)