Optimized pick-random-elements-from-list method.

robotgame/logic/rollingstone.py

@@ -32,7 +32,9 @@ from __future__ import print_function
 import math
 import random
 import itertools
+
 from robotgame.logic.direction import *
+import robotgame.misc as misc
 
 class Blocker(object):
     pass
@@ -89,6 +91,9 @@ def generate_simple_playfield(width, height, nturns, nstones,
 
     'steps' is the number of steps used by the generated solution. It is not
     necessarily the lowest number of steps the playfield can be completed in.
+
+    This generator favours increasing the turn density the closer to the goal
+    it gets.
     """
 
     min_width, min_height = _min_play_size(nturns)
@@ -151,13 +156,10 @@ def generate_simple_playfield(width, height, nturns, nstones,
     del turns[-1]
     for p, d in turns:
         playfield[p] = d
-    emptys = set(itertools.product(range(width),
-                                   range(height))) - set(used_fields)
-    for _ in range(nstones):
-        if not emptys:
-            break
-        pos = random.choice(list(emptys))
-        emptys.remove(pos)
+
+    for pos in misc.pick_random_elements(
+        list(set(itertools.product(range(width), range(height)))
+             - set(used_fields)), nstones):
         playfield[pos] = Blocker
     return playfield, len(used_fields) - 1