Yeah, personally (from my minimal understanding of J), I'd have guessed that feeding the data at rank 1 would be slower, but what do I know?
On 30 April 2014 12:12, Ben Gorte - CITG <[email protected]> wrote: > Sorry, but not on my computer: > > Nx2 =: i.600000 2x > df1=:+ > 6!:2 'z=:df1/ |:Nx2' > 0.46775 > 6!:2 'z=:df1/"1 Nx2' > 1.18481 > > I was thinking in the first case it does df1 only once (on a lot of data), > and in the second case many times, element by element. > > Greetings, > Ben > ________________________________________ > From: [email protected] [ > [email protected]] on behalf of David Lambert [ > [email protected]] > Sent: Wednesday, April 30, 2014 12:48 > To: [email protected] > Subject: Re: [Jprogramming] Applying a dyad to exusting matrix data > > Time to learn about rank! > In my experience > > u"1 N_BY_2_MATRIX > > runs faster than > > u@:|: N_BY_2_MATRIX > > Date: Wed, 30 Apr 2014 10:49:40 +0100 > > From: alexgian<[email protected]> > > To: J Programming forum<[email protected]> > > Subject: [Jprogramming] Applying a dyad to exusting matrix data > > Message-ID: > > <CAD= > [email protected]> > > Content-Type: text/plain; charset=UTF-8 > > > > Suppose I have an Nx2 data matrix, say > > x1 y1 > > x2 y2 > > x3 y3 > > .... > > and a dyadic verb called, say, df1 > > > > > > Is there an elegant way to get the result matrix > > x1 df1 y1 > > x2 df1 y2 > > x3 df1 y3 > > ..... > > > > without resorting to "from - {" and "take - {." jiggery-pokery > > Or perhaps just a means to convert an expresiion from the > > df1 x1 y1 form, to > > x1 df1 y1 > > > > All suggestions gratefully received. > > > > ---------------------------------------------------------------------- > 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
