This is fastest (4x to 5x) on the test sample at your link (I came up with
better name)
lessitems =: [ #~ (i.~ (] - {) /:@/:)@:[ >: ([ i.~ ~.@:]) { 0 ,~ #/.~@:]
it removes from the front, but your change was easy to remove from the back.
Raul's
dfe =: (] #~ #@[ = pi)
slightly slower than
dfe2 =:(] {~ i.@#@] -. pi~)
x (dfe -: dfe2) y
1
x (strikeb2~&.:|. -: dfe2) y
1
----- Original Message -----
From: Jose Mario Quintana <[email protected]>
To: Programming forum <[email protected]>
Sent: Monday, July 25, 2016 1:10 PM
Subject: Re: [Jprogramming] challenge: dyad -. but removing the number of
copies of x in y
One could also just recycle Boss' strikeb2 verb (simplified by Roger) [0],
delfromend=. strikeb2~&.:|. f.
PS. The verb strikeb2 can be rewritten tacitly as,
strikeb2=. [ #~ (i.~ (] - {) /:@/:)@:[ >: ([ i.~ ~.@:]) { 0 ,~ #/.~@:]
[0] [Jforum] Custom fit and set functions
http://www.jsoftware.com/pipermail/general/2004-May/017503.html
On Mon, Jul 25, 2016 at 12:28 PM, Raul Miller <[email protected]> wrote:
> (] {~ i.@#@] -. pi~) does not look right, to me. Instead, I think I'd
> use something like:
>
> dfe=: (] #~ #@[ = pi)&.|.
>
> Or, perhaps:
>
> co=: i:~ (] - {) /:@/:
> ip=: #@[ ({. i.&(,.co) }.) [ i. ,
> dfe=: (] #~ #@[ = ip)
>
> --
> Raul
>
>
>
> On Mon, Jul 25, 2016 at 12:08 PM, 'Pascal Jasmin' via Programming
> <[email protected]> wrote:
> > cool,
> >
> > http://code.jsoftware.com/wiki/Essays/Progressive_Index-Of
> >
> > oc=: i.~ (] - {) /:@/:
> > pi=: #@[ ({. i.&(,.oc) }.) [ i. ,
> >
> > 'a' (] {~ i.@#@] -. pi~) 'cbaab'
> > cbab
> >
> >
> > my original version, (fails some of the order requests)
> >
> >
> > delfromend =: ;@:(] (</.~@[ }.&.>~ {./.) +/@:(=/))
> >
> >
> > 'a' delfromend&, 'cbaab'
> > cbba
> >
> > ----- Original Message -----
> > From: Henry Rich <[email protected]>
> > To: [email protected]
> > Sent: Monday, July 25, 2016 11:02 AM
> > Subject: Re: [Jprogramming] challenge: dyad -. but removing the number
> of copies of x in y
> >
> > See Progressive Index in the Wiki
> >
> > Henry Rich
> >
> > On 7/25/2016 10:41 AM, 'Pascal Jasmin' via Programming wrote:
> >> write function delfromend (naming things is hard) such that
> >>
> >> 'cabd' delfromend 'cbaab'
> >> ba
> >>
> >> 18 (delfromend~ ; delfromend)&q: 54
> >> ┌┬─┐
> >> ││3│
> >> └┴─┘
> >>
> >> 'aaaa' delfromend 'cbaab'
> >> cbb
> >>
> >>
> >>
> >> removes as many instances of x that exist in y. Taking out items from
> the end of y. Though a bit easier is to just group items by "key" for
> output.
> >>
> >>
> >> (,<'a') delfromend ;/ 'cbaab'
> >> ┌─┬─┬─┬─┐
> >> │c│b│b│a│
> >> └─┴─┴─┴─┘
> >> ----------------------------------------------------------------------
> >> For information about J forums see http://www.jsoftware.com/forums.htm
> >
> >
> > ----------------------------------------------------------------------
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