list rotation and WxPytris

Author: eliben

2008/list_rotation.py

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+# This file lists some Python functions for rotating a list 
+# to the left. The emphasis is functions that don't use extra
+# space.
+# For an explanation, see 
+# http://eli.thegreenplace.net/2008/08/29/space-efficient-list-rotation/ 
+#
+# Based on chapter 2 of "Programming Pearls" by Jon Bentley
+#
+# Eli Bendersky (http://eli.thegreenplace.net)
+#
+
+
+def rotate_naive(lst, dist):
+    """ A 'naive' (space inefficient) rotation function.
+        The slice operations create new lists.
+    """
+    lst[:] = lst[dist:len(lst)] + lst[0:dist]
+
+
+def gcd(a, b):
+    """ Greatest common divisor of a and b
+        Using Euclid's algorithm
+    """
+    while b:
+        a, b = b, a % b
+    return a
+
+
+def rotate_juggle(lst, dist):
+    """ An iterative 'juggle' method
+    """
+    n = len(lst)
+        
+    for i in xrange(gcd(dist, n)):
+        t = lst[i]
+        j = i
+        while 1:
+            k = (j + dist) % n
+            if k == i: break
+            lst[j] = lst[k]
+            j = k
+        lst[j] = t
+
+
+def sublist_swap(lst, a, b, m):
+    """ Swaps (in-place) the elements:
+        lst[a:a+m) with lst[b:b+m)
+        Without using extra space.
+        
+        Assumes that all the indices point inside the list.
+    """
+    for i in xrange(m):
+        lst[a + i], lst[b + i] = lst[b + i], lst[a + i]
+        
+
+def rotate_swap(lst, dist):
+    """ A 'recursive' sub-list swapping method.        
+    """
+    n = len(lst)
+    
+    if dist == 0 or dist == n:
+        return
+    i = p = dist
+    j = n - p
+    
+    while i != j:
+        if i > j:
+            sublist_swap(lst, p - i, p, j)
+            i -= j
+        else:
+            sublist_swap(lst, p - i, p + j - i, i)
+            j -= i
+    
+    sublist_swap(lst, p - i, p, i)
+
+
+def sublist_reverse(lst, a, b):
+    """ Reverses (in-place) the elements lst[a:b]
+    """
+    while b > a:
+        lst[a], lst[b] = lst[b], lst[a]
+        b -= 1
+        a += 1
+
+
+def rotate_reverse(lst, dist):
+    """ Uses reversing to rotate the list.
+    """
+    n = len(lst)
+    sublist_reverse(lst, 0, dist - 1)
+    sublist_reverse(lst, dist, n - 1)
+    sublist_reverse(lst, 0, n - 1)
+
+
+import timeit
+
+def benchmark():
+    setup = """
+from __main__ import rotate_naive, rotate_juggle, rotate_reverse, rotate_swap
+
+lst = range(1000000)
+dist = 100000
+"""
+    
+    N = 10
+    print "Naive:", timeit.Timer(stmt='rotate_naive(lst, dist)', setup=setup).timeit(N)
+    print "Juggle:", timeit.Timer(stmt='rotate_juggle(lst, dist)', setup=setup).timeit(N)
+    print "Swap:", timeit.Timer(stmt='rotate_swap(lst, dist)', setup=setup).timeit(N)
+    print "Reverse:", timeit.Timer(stmt='rotate_reverse(lst, dist)', setup=setup).timeit(N)
+
+
+import unittest
+
+class TestListRotation(unittest.TestCase):
+    def do_test_list(self, func, lst, dist, newlst):
+        mylst = lst[:]
+        func(mylst, dist)
+        self.assertEqual(mylst, newlst)
+    
+    def run_tests(self, func):
+        self.do_test_list(func, [], 0, [])
+        self.do_test_list(func, [1], 0, [1])
+        self.do_test_list(func, [1, 2], 0, [1, 2])
+        self.do_test_list(func, [1, 2], 2, [1, 2])
+        self.do_test_list(func, [1, 2], 1, [2, 1])
+        self.do_test_list(func, [1, 2, 3], 1, [2, 3, 1])
+        self.do_test_list(func, [1, 2, 3], 2, [3, 1, 2])
+        
+        N = 500
+        for i in range(N):
+            self.do_test_list(func, range(N), i, range(i, N) + range(i))
+                
+    def test_rotates(self):
+        self.run_tests(rotate_naive)
+        self.run_tests(rotate_juggle)
+        self.run_tests(rotate_swap)
+        self.run_tests(rotate_reverse)
+    
+
+
+if __name__ == '__main__':
+    # Uncomment one of the following
+    #~ unittest.main()
+    benchmark()

2008/wxpytris/lib.zip

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+import sys
+import wx
+
+sys.path.insert(0, 'lib.zip')
+from lib.TetrisGame import TetrisGame
+
+
+if __name__ == '__main__':
+    app = wx.PySimpleApp()
+    frame = TetrisGame(None)
+    frame.Show(True)
+    app.MainLoop()
+
+
+
+
+
+
+

2008/wxpytris/wxpytris.py

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+KGxwMAooUydxJwpwMQpJNDUKdHAyCmEu