add dec8.aux.linlut

dec8/aux.py

@@ -32,6 +32,39 @@ def clamp(A, low, high):
 
 # ----------------------------------------------------------------
 
+def linlut(data, x):
+	"""
+	Data is a list of lists. Data[x][0] must be sorted from lowest to highest.
+	
+	Finds the two records in data where the record[0] is closest to x,
+	and returns a linearly interpolated record.
+	
+	Out of bounds x are clamped to the range in data.
+	"""
+	
+	smaller = None
+	larger = None
+	
+	for d in data:
+		if d[0] <= x:
+			smaller = d
+		
+		elif d[0] > x:
+			larger = d
+			break
+	
+	if not smaller:
+		return data[0]
+	
+	if not larger:
+		return data[-1]
+	
+	ratio = (x - smaller[0]) / (larger[0] - smaller[0])
+	
+	return [(Sy + ratio * (Ly - Sy)) for Sy, Ly in zip(smaller, larger)]
+
+# ----------------------------------------------------------------
+
 import random
 
 PASSPHRASE_VOWELS = "aeiuAEU"