May I suggest you make this into an essay in the Wiki?
On Fri, Aug 10, 2012 at 2:49 PM, Peter B. Kessler <
peter.b.kess...@oracle.com> wrote:
> In response to my request for a solution to the alternating binary array
> problem that uses J's Sequential Machine (;:) verb, Raul Miller posted
> thi
In response to my request for a solution to the alternating binary array
problem that uses J's Sequential Machine (;:) verb, Raul Miller posted this[1]
Here's an implementation which uses ;:
smalt=: 12 > (3;1,~&>0 1 2 3,1 3 2 3,2 1 3 3,:3)&;:@:#.@|:
I thought it would be worth writing Raul's
On Fri, Aug 3, 2012 at 2:43 AM, Ian Shannon
wrote
> NB this also shows that garbage collection or something similar might be
> affecting the times as I obtain different "curves" running this (and similar)
> expressions multiple times.
Yes, you get a lot of features from the host OS and the unde
Roger Hui writes:
>
>timer=: 6!:2
>
>] t=: 3 : 'timer ''+/\a'' [ a=.y?@$0'"0 ] n=: 1e4 * 2 ^ i.7
> 0.000123759 0.000225448 0.000207568 0.000373511 0.00126888 0.00315096
> 0.00598093
>
>load 'plot'
>plot n;t
>
> Looks pretty linear to me.
Linear? well maybe, interesting Yes.
Peter Kessler writes:
> For example, I love the use of "+/\" in the above to propagate the state
of the match.
> (Though, I worry a little about the efficiency of it, if prefix really
reapplies the verb to
> each of the possible prefixes, especially as the inputs get long.)
See Appendix B of the
olution to the
>> alternating 1's problem?
>>
>> Conversely, why is it not J-like to filter out the 0 0 columns (and check
>> for 1 1 columns while you are there), then match successive 2x2 blocks to
>> make sure they are all the same? Either "2 2 $ 0 1 1 0" o
ose an
> order.) I'm sure it would take me hours to construct that expression, and
> maybe I shouldn't spend the time, if that's not the J way to do things like
> this. Is that not J-like because I shouldn't be thinking in terms of
> iterating over the input?
>
> Van: Peter B. Kessler
> Verzonden: maandag 30 juli 2012 22:12
(...)
>
> This doesn't address the case where both inputs have 1's in the same column
>
> ]C=:2 5 $ 1 0 0 1 0 0 1 0 1 0
> 1 0 0 1 0
> 0 1 0 1 0
> (>./-<./)+/\+/1 _1 *C
> 1
>
> The original stateme
Actually, I said something in my previous post which was wrong:
Function code 3 for sequential machine gives state table index.
(This is not useful for a lot of the text processing I would like to
do (where I want the state table index for each character being
processed) but it's fine for this ap
gt;) TESTDATA
fsm=: (FUNCTION;STATE;MAP)&;:
assert(2(#,:)1 1 1 0 1 1 1 0 0 0 0)-:(_1-.@:-:fsm ::_1:)@>TD
> Date: Mon, 30 Jul 2012 13:12:29 -0700
> From: "Peter B. Kessler"
> To: programm...@jsoftware.com
> Subject: Re: [Jprogramming] Determining an 'alterna
mming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Devon
McCormick
Sent: Monday, July 30, 2012 7:24 PM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Determining an 'alternating' binary array
You could implement this latter idea
time, if that's not the J way to do things like
> this. Is that not J-like because I shouldn't be thinking in terms of
> iterating over the input?
>
> I'm trying to learn to think like a J programmer. Thanks for teaching me
> to fish.
>
> .
You could implement this latter idea something like this:
ok0;ok1=. 1|.ok0=. 1 0 ,: 0 1
+---+---+
|1 0|0 1|
|0 1|1 0|
+---+---+
(ok0;ok1) ([: *./ [: }: [: {. [: > [: +.&.>/ [ E.~&.>~ [: < 0 0 -.&.|:~ ]) C
0
]Cok=:2 5 $ 1 0 0 1 0 0 1 0 0 1
1 0 0 1 0
0 1 0 0 1
(ok0;ok1) ([: *./ [: }: [
Thank you, thank you, thank you! I'll digest your mail, spend a few more
productive hours with the Dictionary, and send comments, but this looks like
the kind of explanation I've been wanting.
... peter
Raul Miller wrote:
On Mon, Jul 30, 2012 at 4:12 PM, Peter B. Kess
On Mon, Jul 30, 2012 at 4:12 PM, Peter B. Kessler
wrote:
> In the "alternating binary array" case, it seems, to me, like what's called
> for is a small finite state machine (or regular expression parser, if that's
> how you think). Start in a neutral state, and move to a new state on
> reading a
... peter
-Oorspronkelijk bericht-
Van: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] Namens Linda Alvord
Verzonden: zaterdag 28 juli 2012 9:43
Aan: programm...@jsoftware.com
Onderwerp: Re: [Jprogramming] Determining an 'al
; So A qualifies, B does not.
>
>
> R.E. Boss
>
>
>> -Oorspronkelijk bericht-
>> Van: programming-boun...@forums.jsoftware.com
>> [mailto:programming-boun...@forums.jsoftware.com] Namens Linda Alvord
>> Verzonden: zaterdag 28 juli 2012 9:43
>> Aan: programm..
zonden: zaterdag 28 juli 2012 9:43
> Aan: programm...@jsoftware.com
> Onderwerp: Re: [Jprogramming] Determining an 'alternating' binary array
>
> In this case the tacit version leads to a better explicit definition:
>
>
>al=: 13 :'(-:((2 2$0 1 1 0)$~
Original Message-
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Linda Alvord
Sent: Saturday, July 28, 2012 3:14 AM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Determining an 'alternating' binary arr
re.com] On Behalf Of Linda Alvord
Sent: Saturday, July 28, 2012 2:45 AM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] Determining an 'alternating' binary array
Here's an alternative to 'alternative'
]A=:2 8$ 0 0 1 0 0 0 0 1 1 0 0 0 1 0 0 0
0 0 1 0 0 0 0 1
1 0
[: |: /:~
alt A
1
alt B
0
Linda
-Original Message-
From: programming-boun...@forums.jsoftware.com
[mailto:programming-boun...@forums.jsoftware.com] On Behalf Of Marshall
Lochbaum
Sent: Friday, July 27, 2012 11:56 AM
To: programm...@jsoftware.com
Subject: Re: [Jprogramming] De
Here's another option: convert the two rows into one using base 2, discard
the ones that are 0, and check if the remaining ones are 1 2 1...
I borrowed the sort in Raul's solution so that they must be in that order,
not 2 1 2... .
alternate =: (-: 1 2$~$)@:(0 -.~ #.@|:)@:/:~
Note that we don't ha
Another approach?
alternates =: [: -. 1 e. [: +/ 0 1 |."0 1 ] #"_ 1~ +./
noAnds =: *./@(-.@(*./))
check =: noAnds *. alternates
--
(B=)
--
For information about J forums see http://www.jsoftware.com/forums.htm
alternate=: 0 1 *./@e.~ , , +/,-&(+/\)/&(\:~)
In other words, we are requiring that the following only gives us 1s and 0s:
[a] The starting data
[b] The sums of the two rows
[c] The difference of the running sums of these two rows (rearranging
the rows so that the leftmost 1 appears in the first
I have an array of shape (2 n), and I want to determine if it has a kind of
alternating pattern, where 1s must appear on alternate rows, when reading from
left to right.
Some examples that do 'alternate':
1 0 0 1 0 1
0 1 0 0 1 0
0 1 0 1 0
1 0 1 0 1
0 0 1 0 0 0 0 1
1 0 0 0 1 0 0 0
Some exampl
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