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Re: Converting a set into list

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Date Mon, 16 May 2011 13:37:17 +1100
Subject Re: Converting a set into list
From Daniel Kluev <dan.kluev@gmail.com>
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Xref x330-a1.tempe.blueboxinc.net comp.lang.python:5465

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> Both solutions seem to be equivalent in that concerns the number of needed loop runs, but this two-step operation might require one less loop over list1.
> The set&set solution, in contrary, might require one loop while transforming to a set and another one for the & operation.

python -m timeit -s "l1 = range(1, 10000); l2 = range(5000, 15000)"
"l3 = list(set(l1) & set(l2))"
100 loops, best of 3: 2.19 msec per loop

python -m timeit -s "l1 = range(1, 10000); l2 = range(5000, 15000)"
"s=set(l2); l3 = [i for i in l1 if i in s]"
100 loops, best of 3: 2.45 msec per loop

python -m timeit -s "l1 = range(1, 100000); l2 = range(50000, 150000)"
"l3 = list(set(l1) & set(l2))"
10 loops, best of 3: 28 msec per loop

python -m timeit -s "l1 = range(1, 100000); l2 = range(50000, 150000)"
"s=set(l2); l3 = [i for i in l1 if i in s]"
10 loops, best of 3: 28.1 msec per loop

So even with conversion back into list set&set is still marginally faster.

-- 
With best regards,
Daniel Kluev

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Thread

Converting a set into list TheSaint <nobody@nowhere.net.no> - 2011-05-14 17:02 +0800
  Re: Converting a set into list Peter Otten <__peter__@web.de> - 2011-05-14 11:33 +0200
    Re: Converting a set into list TheSaint <nobody@nowhere.net.no> - 2011-05-14 22:14 +0800
      Re: Converting a set into list Chris Angelico <rosuav@gmail.com> - 2011-05-15 04:22 +1000
  Re: Converting a set into list Ben Finney <ben+python@benfinney.id.au> - 2011-05-15 00:12 +1000
    Re: Converting a set into list TheSaint <nobody@nowhere.net.no> - 2011-05-14 22:51 +0800
      Re: Converting a set into list Ben Finney <ben+python@benfinney.id.au> - 2011-05-15 09:21 +1000
        Re: Converting a set into list Chris Torek <nospam@torek.net> - 2011-05-15 02:11 +0000
          Re: Converting a set into list SigmundV <sigmundv@gmail.com> - 2011-05-15 04:18 -0700
            Re: Converting a set into list SigmundV <sigmundv@gmail.com> - 2011-05-15 04:23 -0700
            Re: Converting a set into list TheSaint <nobody@nowhere.net.no> - 2011-05-15 23:56 +0800
              Re: Converting a set into list Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2011-05-15 22:27 +0200
                Re: Converting a set into list Daniel Kluev <dan.kluev@gmail.com> - 2011-05-16 13:37 +1100
                Re: Converting a set into list Peter Otten <__peter__@web.de> - 2011-05-16 08:34 +0200
                Re: Converting a set into list TheSaint <nobody@nowhere.net.no> - 2011-05-16 22:23 +0800
                Re: Converting a set into list Ben Finney <ben+python@benfinney.id.au> - 2011-05-17 10:33 +1000
            Re: Converting a set into list Roy Smith <roy@panix.com> - 2011-05-15 13:07 -0400
          Re: Converting a set into list TheSaint <nobody@nowhere.net.no> - 2011-05-16 00:05 +0800
            Re: Converting a set into list Steven D'Aprano <steve+comp.lang.python@pearwood.info> - 2011-05-15 16:28 +0000
              Re: Converting a set into list TheSaint <nobody@nowhere.net.no> - 2011-05-16 00:35 +0800
          Re: Converting a set into list Duncan Booth <duncan.booth@invalid.invalid> - 2011-05-16 10:24 +0000
            Re: Converting a set into list Chris Torek <nospam@torek.net> - 2011-05-17 01:07 +0000

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