I've not seen such a case, where [: u v is fast but not u@:v .
Henry Rich
On 1/20/2016 6:09 PM, Jose Mario Quintana wrote:
The experiment was for the specific performance of [: u v vs u @: v for the
given u, v, X and Y. However, there are other instances as well, for
example, the reference [2]. I do not recall seen any instance of such
discrepancy in performance the other way around; that is when [: u v
clearly dominates u @: v but I would be grateful if you or anyone else
points me in that direction.
On Wed, Jan 20, 2016 at 5:40 PM, Henry Rich <[email protected]> wrote:
The experiment you made is insufficient for the purpose.
Usually when u@:v is fast, ([: u v) gets the same treatment. Since
/:@:/: is fast, I expected ([: /: /:) to be also. (It's not, surprisingly).
/:@:/: is handled same as /:@/: since they are equivalent.
<.@% is fast, but there is no reason to expect ([: <. %~) to be fast, for
two reasons:
1. They have different rank. But <.@:% is also fast, so it turns out
this is not the difference.
2. Since <.@:% is fast, so will <.@:%~ be, and normally ([: <. %) too;
but ([: <. %~) is totally different. It is equivalent to <.@:(%~) which
is NOT fast.
I have not been able to figure out what the verbs f are for which <.@f is
fast.
Henry Rich
On 1/20/2016 8:31 AM, 'Pascal Jasmin' via Programming wrote:
does [:/:/: not also benefit from special code?
I doubt it does,
timespacex '123 ([: <. %~) 210293810238120398120398120398x + i.1000'
0.00241248 1.27885e6
timespacex '123 ( <.@%~) 210293810238120398120398120398x + i.1000'
0.000590399 836992
----- Original Message -----
From: Mike Day <[email protected]>
To: [email protected]
Sent: Wednesday, January 20, 2016 7:50 AM
Subject: Re: [Jprogramming] A Different Less?
I wasn't advocating /:/: . I prefer using @ but the 13 : ' .... '
had produced [:/:/: . Conicidentally, Linda appears to
favour the [:u v idiom to u@v .
So, for Linda's benefit, does [:/:/: not also benefit from
special code?
Mike
On 20/01/2016 12:29, Henry Rich wrote:
Note: /:@/: y is better than /: /: y (special code)
Henry Rich
On 1/20/2016 5:45 AM, Mike Day wrote:
Maybe simpler but it requires evaluation of /:/:y twice, whereas
Raul's oc manages to make rank the right hand argument to (] - {) .
This tacitisation might be what you're looking for:
13 :'r-(i.~ y){ r =./:/:y'
i.~ (] - {) [: /: /:
It reproduces oc except for using [: rather than @ !
Mike
On 20/01/2016 10:27, Linda A Alvord wrote:
A simpler f:
f=: 13 :'(/:/:y)-(i.~ y){/:/:y'
f
([: /: /:) - i.~ { [: /: /:
Linda
-----Original Message-----
From: Programming [mailto:[email protected]]
On Behalf Of Linda A Alvord
Sent: Wednesday, January 20, 2016 3:15 AM
To: [email protected]
Subject: Re: [Jprogramming] A Different Less?
Here's another way to write the code that so far is the fastest. How
does it compare?
A=:'abcabbe'
B=:'babe'
f=: 13 :'(/:/:y)-(y i. y){/:/:y'
g=: 13 :'((f x)>: (( ~.y)i.x){(#/.~y),0: y)#x'
A g B
cab
f
([: /: /:) - i.~ { [: /: /:
g
[ #~ ([: f [) >: ([ i.~ [: ~. ]) { ([: #/.~ ]) , [: 0: ]
Linda
-----Original Message-----
From: Programming [mailto:[email protected]]
On Behalf Of Raul Miller
Sent: Monday, January 18, 2016 12:51 PM
To: Programming forum
Subject: Re: [Jprogramming] A Different Less?
Hmm...
A bugfixed version of my previous implementation (it broke when x -.
y was empty) performs approximately the same, for me:
cle=: ,~ #~ i.@#@,~ e. [: ; (2*#/.~@]) (}.&.>~ #@[ {. ])~ (]i.,~)
</. i.@#@,~
I say approximately, because timing variations mean that when I test
on the same data, sometimes it's faster and sometimes it's slower than
oc=: i.~ (] - {) /:@/:
cless =: [ #~ oc@:[ >: (i.~~.) { (#/.~,0:)@]
That said, Boss's implementation is clearly more concise...
Thanks,
--
Raul
On Mon, Jan 18, 2016 at 12:17 PM, Marshall Lochbaum
<[email protected]> wrote:
That's a very cool solution, and much quicker than the one based on
progressive index-of. Instead of taking the occurrence count of both x
and y, it just takes the count for x and compares it to the total
number of occurrences in y, given by (#/.~).
Here's a comparison of the two methods. It turns out in the version
based on progressive index-of, the desired verb can be obtained just
from replacing (i.) with (-.) and then using the first column of the
result to select from x, so I've used that version.
NB. Shared verb for occurrence count
oc=: i.~ (] - {) /:@/:
NB. Simplified form of what Roger and I posted
cless1 =: [ {~ [: {."1 #@[ ({. -.&(,.oc) }.) [ i. ,
NB. Tacitized R.E. Boss solution
cless2 =: [ #~ oc@:[ >: (i.~~.) { (#/.~,0:)@]
NB. test data
'a b' =. 500 ({.;~}.) +&(1e5 ?@$ 26)&.(a.&i.) 'a'
10 (6!:2) 'a cless1 b'
0.0178952
10 (6!:2) 'a cless2 b'
0.0063745
a (cless1 -: cless2) b
1
To summarize, here's the fastest solution so far:
oc=: i.~ (] - {) /:@/:
cless =: [ #~ oc@:[ >: (i.~~.) { (#/.~,0:)@]
Marshall
On Mon, Jan 18, 2016 at 03:49:46PM +0000, R.E. Boss wrote:
I'm getting old, but still remember my solution, improved by Hui:
http://www.jsoftware.com/pipermail/general/2004-May/017503.html
'abcabbe' strikeb2 'babe'
cab
Curious how it performs compared to the other solutions.
R.E. Boss
-----Original Message-----
From: Programming [mailto:[email protected]]
On Behalf Of June Kim (???)
Sent: maandag 18 januari 2016 5:19
To: Programming forum <[email protected]>
Subject: [Jprogramming] A Different Less?
Hello
I am looking for a verb(cless) that does something similar to
Less(-.) but counting the elimination, for example:
'abcabbe' -. 'abbe'
c
'abcabbe' cless 'babe' NB. get rid of y letters counting the
occurrences
'cab'
It is easier to define such a verb recursively: 'abcabbe' cless
'babe'
equald to 'e' cless~ 'b' cless~ 'a' cless~ 'b' cless~ 'abcabbe'
I think recursive definition isn't a usual J-ic approach.
How would you implement such a verb elegantly(with which I mean
short)?
June
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