rainbow2d: nicer distance function !!

host_python/rainbow2d.py

@@ -35,13 +35,23 @@ def lint(x, points, values):
 def set_pixel_2d(bar, x, y, r, g, b):
   bar.set_pixel(WIDTH - x - 1 + y*WIDTH, r, g, b)
 
+def combine(*fncs):
+    return lambda *args: reduce(
+        id,
+        reduce(
+            lambda acc,fnc:(fnc(*acc),), 
+            reversed(fncs), 
+            args)
+    )
+
+def flip(f):
+    return lambda *a: f(*reversed(a))
+
 def cdist(center, point, scale):
-  dist = math.sqrt(reduce(
-    lambda a,b: a+b,
-    map(lambda (x,y): (x-y)**2, zip(center,point))
-  ))
-  dist = dist*scale
-  return dist
+  from operator import add,sub
+  from math import sqrt
+  from functools import partial
+  return scale*sqrt(reduce(add, map(combine(partial(flip(pow),2),sub),center,point)))
 
 l = Ledbar(PIXELS)