http://www.perlmonks.org?node_id=1190610


in reply to Re^3: printing every 2nd entry in a list backwards
in thread printing every 2nd entry in a list backwards

Apologies for not mentioning how I measure performance, please refer to my other reply for more information

  • Comment on Re^4: printing every 2nd entry in a list backwards

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Re^5: printing every 2nd entry in a list backwards
by haukex (Archbishop) on May 19, 2017 at 13:13 UTC

    From this node:

    by creating a file with 1_000_000 entries, each line having 10 numbers and then running the script against it

    I still can't reproduce your evidence.

    $ perl -wMstrict -le 'print join(" ",map {int(rand(100))-50} 1..10) fo
+r 1..1000000' >in.txt
$ time python list.py in.txt >pyout.txt

real    0m1.964s
user    0m1.934s
sys    0m0.028s
$ time perl 1190602.pl in.txt >out2.txt

real    0m1.953s
user    0m1.921s
sys    0m0.028s

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      I just tried it on my laptop: 

      $ python --version
Python 2.7.12
$ time python every-second-item-reversed.py in.txt > pyout.txt

real    0m1.927s
user    0m1.898s
sys    0m0.028s

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      $ perl -v

This is perl 5, version 18, subversion 2 (v5.18.2) built for x86_64-li
+nux-thread-multi
[...]

$ time perl every-second-item-reversed-haukex.py in.txt > haukex-out.t
+xt

real    0m2.309s
user    0m2.290s
sys    0m0.020s

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      No differences in the two output files. However, note Perl 5.24.1 is faster than both Python 2.7.12 and Perl 5.18.1: 

      $ perl5.24.1 -v

This is perl 5, version 24, subversion 1 (v5.24.1) built for x86_64-li
+nux-thread-multi
[...]

$ time perl5.24.1 every-second-item-reversed-haukex.py in.txt > haukex
+-out-5.24.1.txt

real    0m1.759s
user    0m1.740s
sys    0m0.016s

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      And also Python 3.4 is slower than any of the above: 

      $ python3.4 --version
Python 3.4.5
$ time python3.4 every-second-item-reversed.py in.txt > pyout-3.4.txt

real    0m2.493s
user    0m2.444s
sys    0m0.048s

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        Good point! In my test above I was pitting Python 2.7.6 against Perl 5.22.0. I can confirm that both Perl 5.18.2. and Python 3.4.3 are slower by a factor of roughly 1.3 to 1.4 on my machine (those are just the versions I have lying around at the moment).

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