# [erlang-questions 4] A sudoku solver in Erlang compared to Python

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## [erlang-questions 4] A sudoku solver in Erlang compared to Python

 Hi all, In my quest to learn Erlang I've translated Peter Norvig's sudoku solver into Erlang: https://github.com/apauley/sudoku-in-erlangFor comparison, my slightly modified version of Norvig's Python code can be found here: https://github.com/apauley/sudoku-by-norvigI like the pattern matching, it was fun to do the entire solution without a single if or case statement :-) Something that bothers me though is that the Python solution seems to be faster, even after I've made the Erlang solution use multiple processors. In order to compare the two solutions I counted the number of eliminations each performed. The eliminate function is the core of the solution, for example assigning a single value to a square is implemented as the elimination of all other values. With the Erlang implementation I get: sudoku-in-erlang\$ ./sudoku All tests passed :-) Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz)   (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz)   (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz)   (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). And with the Python implementation: sudoku-by-norvig\$ ./sudoku.py All tests pass. Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz)   (33059 total eliminations, avg 661.00, median 648, max 830, min 648). Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz)   (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz)   (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). So according to the stats above, the Python solution performs less computations when given exactly the same input. The Erlang code is as close to the Python as I could make it, I've done more or less a direct translation of the algorithms used. I suspect that there are some lazy evaluation happening in the Python version, possibly generators, although I haven't pinpointed it yet. How can I improve my Erlang code in this solution? Kind regards, Andreas _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 18] Re: A sudoku solver in Erlang compared to Python

 Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): Without native set: 18> c(sudoku). {ok,sudoku} 19>  sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). ok With native set: 20> c(sudoku,[native]). {ok,sudoku} 21>  sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley Sent: Friday, March 25, 2011 8:15 AM To: [hidden email] Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python Hi all, In my quest to learn Erlang I've translated Peter Norvig's sudoku solver into Erlang: https://github.com/apauley/sudoku-in-erlangFor comparison, my slightly modified version of Norvig's Python code can be found here: https://github.com/apauley/sudoku-by-norvigI like the pattern matching, it was fun to do the entire solution without a single if or case statement :-) Something that bothers me though is that the Python solution seems to be faster, even after I've made the Erlang solution use multiple processors. In order to compare the two solutions I counted the number of eliminations each performed. The eliminate function is the core of the solution, for example assigning a single value to a square is implemented as the elimination of all other values. With the Erlang implementation I get: sudoku-in-erlang\$ ./sudoku All tests passed :-) Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz)   (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz)   (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz)   (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). And with the Python implementation: sudoku-by-norvig\$ ./sudoku.py All tests pass. Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz)   (33059 total eliminations, avg 661.00, median 648, max 830, min 648). Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz)   (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz)   (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). So according to the stats above, the Python solution performs less computations when given exactly the same input. The Erlang code is as close to the Python as I could make it, I've done more or less a direct translation of the algorithms used. I suspect that there are some lazy evaluation happening in the Python version, possibly generators, although I haven't pinpointed it yet. How can I improve my Erlang code in this solution? Kind regards, Andreas _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions_______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 20] Re: A sudoku solver in Erlang compared to Python

 Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbbStrangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang> > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig> > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions> _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 31] Re: A sudoku solver in Erlang compared to Python

 using gb_sets instead of sets could decrease eliminations a bit and give u some boost. However, i didn't dive deeper into the code or the algorithm.On Sat, Mar 26, 2011 at 9:41 AM, Andreas Pauley wrote: Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbb Strangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2 The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang > > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig > > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions > _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions -- Best Regards,- Ahmed Omarhttp://nl.linkedin.com/in/adiaaFollow me on twitter @spawn_think _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 32] Re: A sudoku solver in Erlang compared to Python

 In reply to this post by Andreas Pauley Cool... Might also want to look at what happens if all the other Erlang modules (esp. lists, sets and dict for your app) are made native: Without native set: 18> c(sudoku).  {ok,sudoku} 19>  sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). ok With native set: 20> c(sudoku,[native]). {ok,sudoku} >  sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz)  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). ok Dict/lists/sets native too: 5>  sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 0.996860 secs (95.30 Hz) (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). ok Over a 2x boost in performance with zero re-factoring of your original code....maybe I'll put a question to the group out there. Seems that they should be shouting this sort of improvement from the roof-tops... Matt ________________________________________ From: Andreas Pauley [[hidden email]] Sent: Saturday, March 26, 2011 4:41 AM To: Evans, Matthew Cc: [hidden email] Subject: Re: [erlang-questions 4] A sudoku solver in Erlang compared to Python Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbbStrangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang> > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig> > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions> _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 35] Re: A sudoku solver in Erlang compared to Python

 In reply to this post by Ahmed Omar Good call....gb_sets should be faster. Compiled to native it runs faster still 9> sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 0.810156 secs (117.26 Hz) (901201 total eliminations, avg 9486.33, median 6267, max 56820, min 1792). ok ________________________________________ From: Ahmed Omar [[hidden email]] Sent: Saturday, March 26, 2011 3:08 PM To: Andreas Pauley Cc: Evans, Matthew; [hidden email] Subject: Re: [erlang-questions 20] Re: A sudoku solver in Erlang compared to Python using gb_sets instead of sets could decrease eliminations a bit and give u some boost. However, i didn't dive deeper into the code or the algorithm. On Sat, Mar 26, 2011 at 9:41 AM, Andreas Pauley <[hidden email]> wrote: Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbbStrangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang> > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig> > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions> _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions-- Best Regards, - Ahmed Omar http://nl.linkedin.com/in/adiaaFollow me on twitter @spawn_think _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 36] Re: A sudoku solver in Erlang compared to Python

 Are you solving the puzzles in parallel?  It might be revealing to see the implementation differences  in python and erlang for solving a lot of puzzles when the code parallelized.  The erlang code won't change much. On Sat, Mar 26, 2011 at 3:14 PM, Evans, Matthew wrote: Good call....gb_sets should be faster. Compiled to native it runs faster still 9> sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 0.810156 secs (117.26 Hz) (901201 total eliminations, avg 9486.33, median 6267, max 56820, min 1792). ok ________________________________________ From: Ahmed Omar [[hidden email]] Sent: Saturday, March 26, 2011 3:08 PM To: Andreas Pauley Cc: Evans, Matthew; [hidden email] Subject: Re: [erlang-questions 20] Re: A sudoku solver in Erlang compared to Python using gb_sets instead of sets could decrease eliminations a bit and give u some boost. However, i didn't dive deeper into the code or the algorithm. On Sat, Mar 26, 2011 at 9:41 AM, Andreas Pauley <[hidden email]> wrote: Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbb Strangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2 The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang > > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig > > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions > _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions -- Best Regards, - Ahmed Omar http://nl.linkedin.com/in/adiaa Follow me on twitter @spawn_think _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 37] Re: A sudoku solver in Erlang compared to Python

 In reply to this post by Evans, Matthew actually instead of doing ```    NonUniquePeers = shallow_flatten([S || S <- units(Square)]),     PeerSet = sets:from_list(NonUniquePeers),     PeersWithSelf = sets:to_list(PeerSet), can't u just do PeersWithSelf = lists:usort(NonUniquePeers). ? ```On Sat, Mar 26, 2011 at 9:14 PM, Evans, Matthew wrote: Good call....gb_sets should be faster. Compiled to native it runs faster still 9> sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 0.810156 secs (117.26 Hz) (901201 total eliminations, avg 9486.33, median 6267, max 56820, min 1792). ok ________________________________________ From: Ahmed Omar [[hidden email]] Sent: Saturday, March 26, 2011 3:08 PM To: Andreas Pauley Cc: Evans, Matthew; [hidden email] Subject: Re: [erlang-questions 20] Re: A sudoku solver in Erlang compared to Python using gb_sets instead of sets could decrease eliminations a bit and give u some boost. However, i didn't dive deeper into the code or the algorithm. On Sat, Mar 26, 2011 at 9:41 AM, Andreas Pauley <[hidden email]> wrote: Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbb Strangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2 The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang > > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig > > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions > _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions -- Best Regards, - Ahmed Omar http://nl.linkedin.com/in/adiaa Follow me on twitter @spawn_think -- Best Regards,- Ahmed Omarhttp://nl.linkedin.com/in/adiaaFollow me on twitter@spawn_think _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 39] Re: A sudoku solver in Erlang compared to Python

 BTW, beside looking into reducing eleminations (which requires deep dive), if u do some time profiling using eprof u will find that most of the time spent actually in the cross functions sudoku:'-cross/2-lc\$^1/1-1-'/4                       96558660  37.46  35024918  [      0.36] On Sat, Mar 26, 2011 at 9:33 PM, Ahmed Omar wrote: actually instead of doing ```    NonUniquePeers = shallow_flatten([S || S <- units(Square)]),     PeerSet = sets:from_list(NonUniquePeers),     PeersWithSelf = sets:to_list(PeerSet), can't u just do PeersWithSelf = lists:usort(NonUniquePeers). ? ```On Sat, Mar 26, 2011 at 9:14 PM, Evans, Matthew wrote: Good call....gb_sets should be faster. Compiled to native it runs faster still 9> sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 0.810156 secs (117.26 Hz) (901201 total eliminations, avg 9486.33, median 6267, max 56820, min 1792). ok ________________________________________ From: Ahmed Omar [[hidden email]] Sent: Saturday, March 26, 2011 3:08 PM To: Andreas Pauley Cc: Evans, Matthew; [hidden email] Subject: Re: [erlang-questions 20] Re: A sudoku solver in Erlang compared to Python using gb_sets instead of sets could decrease eliminations a bit and give u some boost. However, i didn't dive deeper into the code or the algorithm. On Sat, Mar 26, 2011 at 9:41 AM, Andreas Pauley <[hidden email]> wrote: Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbb Strangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2 The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang > > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig > > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions > _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions -- Best Regards, - Ahmed Omar http://nl.linkedin.com/in/adiaa Follow me on twitter @spawn_think -- Best Regards,- Ahmed Omarhttp://nl.linkedin.com/in/adiaaFollow me on twitter @spawn_think -- Best Regards,- Ahmed Omarhttp://nl.linkedin.com/in/adiaaFollow me on twitter@spawn_think _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 40] Re: A sudoku solver in Erlang compared to Python

 With a few refactorings (https://github.com/tsloughter/sudoku-in-erlang -- note I used ewl_plists just to make the code simpler: https://github.com/erlware/erlware/tree/master/lib/ewlib) and compile with native, hipe o3 it beats python's: \$ ./sudoku.py All tests pass.Solved 50 of 50 puzzles from easy50.txt in 0.529119 secs (94.50 Hz)  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). Solved 95 of 95 puzzles from top95.txt in 3.889944 secs (24.42 Hz)  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648).Solved 11 of 11 puzzles from hardest.txt in 0.157520 secs (69.83 Hz)   (9436 total eliminations, avg 857.00, median 817, max 1198, min 648).\$ ./sudoku All tests passed :-)Solved 50 of 50 puzzles from easy50.txt in 0.556385 secs (89.87 Hz)   (92538 total eliminations, avg 1850.76, median 1811, max 2628, min 1767).Solved 95 of 95 puzzles from top95.txt in 3.593476 secs (26.44 Hz)  (901201 total eliminations, avg 9486.33, median 6267, max 56820, min 1792). Solved 11 of 11 puzzles from hardest.txt in 0.162107 secs (67.86 Hz)  (33653 total eliminations, avg 3059.36, median 3023, max 5346, min 1786).I ran a number of times, those are pretty much what it always comes out to. But I haven't really tried a full refactoring, I think a number of things can be reduced to less iterations.TristanOn Sat, Mar 26, 2011 at 3:39 PM, Ahmed Omar wrote: BTW, beside looking into reducing eleminations (which requires deep dive), if u do some time profiling using eprof u will find that most of the time spent actually in the cross functions  sudoku:'-cross/2-lc\$^1/1-1-'/4                       96558660  37.46  35024918  [      0.36] On Sat, Mar 26, 2011 at 9:33 PM, Ahmed Omar wrote: actually instead of doing ```    NonUniquePeers = shallow_flatten([S || S <- units(Square)]),     PeerSet = sets:from_list(NonUniquePeers),     PeersWithSelf = sets:to_list(PeerSet), can't u just do PeersWithSelf = lists:usort(NonUniquePeers). ? ```On Sat, Mar 26, 2011 at 9:14 PM, Evans, Matthew wrote: Good call....gb_sets should be faster. Compiled to native it runs faster still 9> sudoku:print_results("top95.txt", "\n"). Solved 95 of 95 puzzles from top95.txt in 0.810156 secs (117.26 Hz) (901201 total eliminations, avg 9486.33, median 6267, max 56820, min 1792). ok ________________________________________ From: Ahmed Omar [[hidden email]] Sent: Saturday, March 26, 2011 3:08 PM To: Andreas Pauley Cc: Evans, Matthew; [hidden email] Subject: Re: [erlang-questions 20] Re: A sudoku solver in Erlang compared to Python using gb_sets instead of sets could decrease eliminations a bit and give u some boost. However, i didn't dive deeper into the code or the algorithm. On Sat, Mar 26, 2011 at 9:41 AM, Andreas Pauley <[hidden email]> wrote: Thanks, I've changed the compile options and this definitely makes it somewhat faster: https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbb Strangely the native flag is not documented here: http://www.erlang.org/doc/man/compile.html#file-2 The more interesting improvement would be to decrease the number of eliminations performed, but for that I'll have to go deep into the code :-) On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> wrote: > Without going deep into the code, one thing to try is compile with the native flag (running the tests from the VM shell here): > > Without native set: > 18> c(sudoku). > {ok,sudoku} > 19>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > ok > > > With native set: > 20> c(sudoku,[native]). > {ok,sudoku} > 21>  sudoku:print_results("top95.txt", "\n"). > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > > > > -----Original Message----- > From: [hidden email] [mailto:[hidden email]] On Behalf Of Andreas Pauley > Sent: Friday, March 25, 2011 8:15 AM > To: [hidden email] > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to Python > > Hi all, > > In my quest to learn Erlang I've translated Peter Norvig's sudoku > solver into Erlang: > https://github.com/apauley/sudoku-in-erlang > > For comparison, my slightly modified version of Norvig's Python code > can be found here: > https://github.com/apauley/sudoku-by-norvig > > I like the pattern matching, it was fun to do the entire solution > without a single if or case statement :-) > Something that bothers me though is that the Python solution seems to > be faster, even after I've made the Erlang solution use multiple > processors. > > In order to compare the two solutions I counted the number of > eliminations each performed. > The eliminate function is the core of the solution, for example > assigning a single value to a square is implemented as the elimination > of all other values. > > With the Erlang implementation I get: > sudoku-in-erlang\$ ./sudoku > All tests passed :-) > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min 1770). > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min 1797). > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min 1781). > > And with the Python implementation: > sudoku-by-norvig\$ ./sudoku.py > All tests pass. > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min 648). > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). > > So according to the stats above, the Python solution performs less > computations when given exactly the same input. > The Erlang code is as close to the Python as I could make it, I've > done more or less a direct translation of the algorithms used. > > I suspect that there are some lazy evaluation happening in the Python > version, possibly generators, although I haven't pinpointed it yet. > > How can I improve my Erlang code in this solution? > > Kind regards, > Andreas > _______________________________________________ > erlang-questions mailing list > [hidden email] > http://erlang.org/mailman/listinfo/erlang-questions > _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions -- Best Regards, - Ahmed Omar http://nl.linkedin.com/in/adiaa Follow me on twitter @spawn_think -- Best Regards,- Ahmed Omarhttp://nl.linkedin.com/in/adiaaFollow me on twitter @spawn_think -- Best Regards,- Ahmed Omarhttp://nl.linkedin.com/in/adiaaFollow me on twitter @spawn_think _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 41] Re: A sudoku solver in Erlang compared to Python

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## [erlang-questions 44] Re: A sudoku solver in Erlang compared to Python

 Surely totally unrelated, but the words "erlang" and "sudoku" always make me remember of http://www.erlang-solutions.com/section/47/2006-competition#FirstPrizeB:) -- Olivier _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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## [erlang-questions 46] Re: A sudoku solver in Erlang compared to Python

 On 27 Mar 2011, at 04:26, Olivier Girondel wrote: > http://www.erlang-solutions.com/section/47/2006-competition#FirstPrizeB?or this one: http://www.erlang-solutions.com/section/48/2005-competition#SecondPrizeSurely the most beautiful Erlang program ever written! BR, Ulf W Ulf Wiger, CTO, Erlang Solutions, Ltd. http://erlang-solutions.com-------------- next part -------------- An HTML attachment was scrubbed... URL:
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## [erlang-questions 49] Re: A sudoku solver in Erlang compared to Python

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## [erlang-questions 51] Re: A sudoku solver in Erlang compared to Python

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## [erlang-questions 56] Re: A sudoku solver in Erlang compared to Python

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## [erlang-questions 57] Re: A sudoku solver in Erlang compared to Python

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## [erlang-questions 58] Re: A sudoku solver in Erlang compared to Python

 In reply to this post by Ahmed Omar Thanks! I didn't think about the sets at all :-) https://github.com/apauley/sudoku-in-erlang/commit/a02fbcd001a9fbd876725008d58c52fcff9872d9On Sat, Mar 26, 2011 at 9:08 PM, Ahmed Omar <[hidden email]> wrote: > using gb_sets instead of sets could decrease eliminations a bit and give u > some boost. However, i didn't dive deeper into the code or the algorithm. > > On Sat, Mar 26, 2011 at 9:41 AM, Andreas Pauley <[hidden email]> wrote: >> >> Thanks, I've changed the compile options and this definitely makes it >> somewhat faster: >> >> https://github.com/apauley/sudoku-in-erlang/commit/b7ce2abb6ca013850ed8f3e8fd7f5f6be7004cbb>> >> Strangely the native flag is not documented here: >> http://www.erlang.org/doc/man/compile.html#file-2>> >> The more interesting improvement would be to decrease the number of >> eliminations performed, but for that I'll have to go deep into the >> code :-) >> >> >> On Sat, Mar 26, 2011 at 12:16 AM, Evans, Matthew <[hidden email]> >> wrote: >> > Without going deep into the code, one thing to try is compile with the >> > native flag (running the tests from the VM shell here): >> > >> > Without native set: >> > 18> c(sudoku). >> > {ok,sudoku} >> > 19>  sudoku:print_results("top95.txt", "\n"). >> > Solved 95 of 95 puzzles from top95.txt in 2.038825 secs (46.60 Hz) >> > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min >> > 1797). >> > ok >> > >> > >> > With native set: >> > 20> c(sudoku,[native]). >> > {ok,sudoku} >> > 21>  sudoku:print_results("top95.txt", "\n"). >> > Solved 95 of 95 puzzles from top95.txt in 1.613416 secs (58.88 Hz) >> > (922678 total eliminations, avg 9712.40, median 6596, max 55370, min >> > 1797). >> > >> > >> > >> > -----Original Message----- >> > From: [hidden email] >> > [mailto:[hidden email]] On Behalf Of Andreas Pauley >> > Sent: Friday, March 25, 2011 8:15 AM >> > To: [hidden email] >> > Subject: [erlang-questions 4] A sudoku solver in Erlang compared to >> > Python >> > >> > Hi all, >> > >> > In my quest to learn Erlang I've translated Peter Norvig's sudoku >> > solver into Erlang: >> > https://github.com/apauley/sudoku-in-erlang>> > >> > For comparison, my slightly modified version of Norvig's Python code >> > can be found here: >> > https://github.com/apauley/sudoku-by-norvig>> > >> > I like the pattern matching, it was fun to do the entire solution >> > without a single if or case statement :-) >> > Something that bothers me though is that the Python solution seems to >> > be faster, even after I've made the Erlang solution use multiple >> > processors. >> > >> > In order to compare the two solutions I counted the number of >> > eliminations each performed. >> > The eliminate function is the core of the solution, for example >> > assigning a single value to a square is implemented as the elimination >> > of all other values. >> > >> > With the Erlang implementation I get: >> > sudoku-in-erlang\$ ./sudoku >> > All tests passed :-) >> > Solved 50 of 50 puzzles from easy50.txt in 2.890978 secs (17.30 Hz) >> >  (93403 total eliminations, avg 1868.06, median 1810, max 2517, min >> > 1770). >> > Solved 95 of 95 puzzles from top95.txt in 22.004369 secs (4.32 Hz) >> >  (922678 total eliminations, avg 9712.40, median 6596, max 55370, min >> > 1797). >> > Solved 11 of 11 puzzles from hardest.txt in 0.851678 secs (12.92 Hz) >> >  (32339 total eliminations, avg 2939.91, median 2894, max 4779, min >> > 1781). >> > >> > And with the Python implementation: >> > sudoku-by-norvig\$ ./sudoku.py >> > All tests pass. >> > Solved 50 of 50 puzzles from easy50.txt in 0.792008 secs (63.13 Hz) >> >  (33059 total eliminations, avg 661.00, median 648, max 830, min 648). >> > Solved 95 of 95 puzzles from top95.txt in 5.903875 secs (16.09 Hz) >> >  (221997 total eliminations, avg 2336.00, median 1492, max 11512, min >> > 648). >> > Solved 11 of 11 puzzles from hardest.txt in 0.237532 secs (46.31 Hz) >> >  (9436 total eliminations, avg 857.00, median 817, max 1198, min 648). >> > >> > So according to the stats above, the Python solution performs less >> > computations when given exactly the same input. >> > The Erlang code is as close to the Python as I could make it, I've >> > done more or less a direct translation of the algorithms used. >> > >> > I suspect that there are some lazy evaluation happening in the Python >> > version, possibly generators, although I haven't pinpointed it yet. >> > >> > How can I improve my Erlang code in this solution? >> > >> > Kind regards, >> > Andreas >> > _______________________________________________ >> > erlang-questions mailing list >> > [hidden email] >> > http://erlang.org/mailman/listinfo/erlang-questions>> > >> _______________________________________________ >> erlang-questions mailing list >> [hidden email] >> http://erlang.org/mailman/listinfo/erlang-questions> > > > -- > Best Regards, > - Ahmed Omar > http://nl.linkedin.com/in/adiaa> Follow me on twitter > @spawn_think > _______________________________________________ erlang-questions mailing list [hidden email] http://erlang.org/mailman/listinfo/erlang-questions
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