Just out of curiosity, surely the data didn't start out as an array of
boxes. Perhaps it might be faster not to have everything boxed. Validation
could be done once on the original source.
On Fri, Apr 13, 2018, 1:24 PM Joe Bogner <joebog...@gmail.com> wrote:
> Well, I stumbled upon a fast way that takes advantage of simple
> multiplication
>
> _ * 0 = 0
> _ * 1 = _
> 5 * 1 = 5
>
>
> _3 {. (-.@isblank * _&".) c1
> 1.01 _ 0
> (6!:2) '(isblank * _&".) c1'
> 1.00593
>
> I'm still interested in alternatives that are similar speed if possible
>
>
>
>
>
> On Fri, Apr 13, 2018 at 3:19 PM, Joe Bogner <joebog...@gmail.com> wrote:
>
> > Thank you -- Yes, I didn't want to send along the full sample, although I
> > could have created some dummy data.
> >
> > Both Don and Raul's method are similar and are equally slow as the way I
> > had
> >
> > It's not terribly important but I have like 10 numeric columns that I
> > convert in a script and have to painfully wait 30 seconds each time I run
> > the script. If I could shave 20 seconds off something that I seem to be
> > running multiple times a day and learn something in the process, I
> figured
> > it was worthwhile to ask
> >
> > (6!:2) '{.@(_&".)"1 c'
> > 3.44371
> >
> > Here's a reasonable approximation:
> >
> > c1 =. 1.5e6 # (>' ';'bad';'10')
> >
> >
> > c1=: (((5e6,4)$'1.01'),'bad'),' '
> > $ c1
> > 5000002 4
> > (6!:2) '{.@(_&".)"1 c1'
> > 3.29915
> >
> >
> > Compare to
> >
> > (6!:2) '_ ". c1'
> > 1.01854
> >
> > _3 {. _ ". c1 NB. bad values at the end... ideally the blank is 0
> though
> > 1.01 _ _
> >
> >
> > On Fri, Apr 13, 2018 at 2:13 PM, Raul Miller <rauldmil...@gmail.com>
> > wrote:
> >
> >> Your sample data does not match your problem description.
> >>
> >> That said,
> >>
> >> {.@(_&".)"1 > ' ';'bad';'10'
> >> 0 _ 10
> >>
> >> Thanks,
> >>
> >> --
> >> Raul
> >>
> >>
> >> On Fri, Apr 13, 2018 at 2:03 PM, Joe Bogner <joebog...@gmail.com>
> wrote:
> >> > I have a large byte array that I want to convert to a number array. I
> >> want
> >> > to use _ to indicate a bad value, but blank should be treated as 0
> >> >
> >> > $ c
> >> > 4862343 10
> >> >
> >> > Instead of this:
> >> >
> >> > asnumber =: _&".
> >> >
> >> > asnumber (>' ';'bad';'10')
> >> > _ _ 10
> >> >
> >> > I want this:
> >> >
> >> >
> >> > asnumber (>' ';'bad';'10')
> >> > 0 _ 10
> >> >
> >> > This works, but is much slower than I'd like -- nearly 3x slower than
> >> just
> >> > _ ".
> >> >
> >> > asnumber =: _ ". '0' ,~^:([: */ ' '&=@])"1 ]
> >> > asnumber (>' ';'bad';'10')
> >> > 0 _ 10
> >> >
> >> > (6!:2) 'asnumber c'
> >> > 3.32579
> >> > (6!:2) '_&". c'
> >> > 1.35091
> >> >
> >> >
> >> > I have an isblank function that is fast
> >> >
> >> > isblank =. ([: ({. -:"1 }.) ' '&,)
> >> > (6!:2) 'isblank c'
> >> > 0.033164
> >> >
> >> > I can't seem to combine the two into something that performs well
> >> without
> >> > doing things at the atom/row level instead of the entire array. I
> >> suspect
> >> > I'm getting tripped up by rank
> >> > ----------------------------------------------------------------------
> >> > For information about J forums see
> http://www.jsoftware.com/forums.htm
> >> ----------------------------------------------------------------------
> >> For information about J forums see http://www.jsoftware.com/forums.htm
> >>
> >
> >
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
