If anyone want to play with this, they should have a copy of the HR file:
https://github.com/christophschmalhofer/poker/blob/master/XPokerEval/XPokerEval.TwoPlusTwo/HandRanks.dat
Or you can download the entire repository from github.
You can use the "View Raw" link to download a copy.
I was hoping you could use map_jmf_ to load a copy of the file, but
unfortunately that's currently broken for 64 bit j804 (or at least for
the j804 version I'm currently running.
F=:
'/Users/rauldmiller/src/poker-master/XPokerEval/XPokerEval.TwoPlusTwo/HandRanks.dat'
load'jmf'
JINT map_jmf_ 'HR';F
#HR
16243917
That should be 3590398
So although JINT is 4 (4 bytes per integer) my J implementation is
acting like it's 8 bytes per integer.
So, let's do this the other way. If you are copying my footsteps,
you'll want to cleanup first:
erase 'HR'
1
unmapall_jmf_''
0
Then:
HR=: _2 ic fread F
#HR
32487834
#~.HR
620299
(HR {~ +)/@:(,&53) 1 5 9 12 20 25 42
8730
In contrast:
(HR {~ +/)@:(,&53) 1 5 9 12 20 25 42
5830
By the way, if you want a slightly deeper dive into the result we're
generating here:
handtypes=:<;._2]0 :0
high card
pair
2 pairs
3 of a kind
straight
flush
full house
4 of a kind
straight flush
)
handtypes {::~ <.4096 %~ (HR {~ +)/@:(,&53) 1 5 9 12 20 25 42
pair
Anyways...
My impression is that this algorithm is a carefully designed highly
sequential algorithm. J runs those slowly. If you want performance, I
think you should use J's
http://www.jsoftware.com/help/user/call_procedure.htm mechanism to run
that routine (compile a cover function designed for pulling the
argument data from a J array and exporting the result to a J array and
compile that with a C api). This would give you the performance of
the scalar algorithm and the convenience of J's interactive
environment. Of course, there's a bit of work in setting that up in
the first place, but honestly some work is unavoidable for anything
worth doing.
But maybe my initial impression wrong and there's some transformation
of that data set which gives adequate performance in J? I'm not seeing
anything like that, but I've been wrong plenty of times before...
Anyways... I hope this helps.
Thanks,
--
Raul
On Sun, Jan 3, 2016 at 9:15 AM, 'Pascal Jasmin' via Programming
<[email protected]> wrote:
> (HR {~ +)/@:(,&53)
>
>
> I'm not sure why the sum is a useful index as I don't think its unique, but
> you are repeating for each card. Perhaps this is intended?
>
>
> (HR {~ +/)@:(,&53)
>
> ----- Original Message -----
> From: Ryan Eckbo <[email protected]>
> To: J-programming forum <[email protected]>
> Sent: Saturday, January 2, 2016 10:56 PM
> Subject: [Jprogramming] Faster array lookup? (poker hand evaluator)
>
> I've implemented the twoplustwo 7 card poker hand evaluator[1] in J but
> it's
> slower than I expected. The evaluator works by accepting an array of 7
> integers between 1 and 52, representing a 7 card hand, and uses them as
> indices
> in a lookup table, which returns the best 5 card hand's rank value.
> Here's the
> C code that does this (HR is the lookup table):
>
> int LookupHand(int* pCards)
> {
> int p = HR[53 + *pCards++];
> p = HR[p + *pCards++];
> p = HR[p + *pCards++];
> p = HR[p + *pCards++];
> p = HR[p + *pCards++];
> p = HR[p + *pCards++];
> return HR[p + *pCards++];
> }
>
> My J version is:
>
> hr=: (HR {~ +)/@:(,&53) NB. hr 1 5 9 12 20 25 42
>
> This is one of the fastest evaluators out there, for example a
> javascript version
> can run at 20 million evaluations per second. My J version takes 30
> seconds
> to evaluate just 10 million hands:
>
> hands=. 53,.~ >: ? 1e7 7 $ 52 NB. 10 million hands, with initial index
> 53 added
> 6!:2 '(HR {~ +)/"1 hands' NB. 32.14 sec on a 2.8GHz Mac
>
> I wonder why it's slow and if there's a way to make it faster?
>
>
> [1]
> https://github.com/christophschmalhofer/poker/blob/master/XPokerEval/XPokerEval.TwoPlusTwo.Test/test.cpp
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