First attempt at a Python prog (Chess)

Ian Kelly ian.g.kelly at gmail.com
Thu Feb 14 19:30:55 CET 2013


On Thu, Feb 14, 2013 at 10:48 AM, Chris Hinsley <chris.hinsley at gmail.com> wrote:
> Is a Python list as fast as a bytearray ? I didn't copy a C prog BTW !

>>> from timeit import Timer
>>> t1 = Timer("board[36] = board[20]; board[20] = ' '", "board = bytearray('RNBQKBNRPPPPPPPP                                pppppppprnbqkbnr')")
>>> min(t1.repeat(10))
0.1678651895701826
>>> t2 = Timer("board[3][4] = board[1][4]; board[1][4] = ' '", "board = [list('RNBQKBNR'), ['P'] * 8] + [[' ']*8 for i in range(4)] + [['p'] * 8, list('rnbqkbnr')]")
>>> min(t2.repeat(10))
0.2080088391122672

Natively, it looks like the bytearray is about 19% faster for moving a
piece from one square to another.  Those array offsets aren't
calculated for free, though.  Look what happens when we have to do the
math:

>>> t3 = Timer("board[r1*8+c1] = board[r2*8+c2]; board[r2*8+c2] = ' '", "board = bytearray('RNBQKBNRPPPPPPPP                                pppppppprnbqkbnr'); r1 = 3; r2 = 1; c1 = c2 = 4")
>>> min(t3.repeat(10))
0.314191887516472
>>> t4 = Timer("board[r1][c1] = board[r2][c2]; board[r2][c2] = ' '", "board = [list('RNBQKBNR'), ['P'] * 8] + [[' ']*8 for i in range(4)] + [['p'] * 8, list('rnbqkbnr')]; r1 = 3; r2 = 1; c1 = c2 = 4")
>>> min(t4.repeat(10))
0.24427881197186707

That said, the philosophy of Python focuses more on readability than
on speed.  The goalpost for speed in a Python program is that it be
"fast enough".  If you have more stringent speed requirements than
that, then Python may not be the right tool for the job.



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