After reading this thread, it is very apparent to me I have a long....... long........ way to go. It isn't only the lack of skills in using J, but also my not even understanding the terminology being used.
Oh well, at least it will cause the little gray cells to work harder. regards from the High Desert in California, USA ----- Original Message Follows ----- From: "Devon McCormick" <[EMAIL PROTECTED]> To: "General forum" <[email protected]> Subject: Re: [Jgeneral] (i. 2 3) i. 4 NB. you know what i mean... how do i get it to work?! Date: Fri, 4 May 2007 11:23:01 -0400 >Terence - > >the vocabulary page for "i.", while technically correct in >stipulating that the left rank of this verb is infinite, is >perhaps misleading in that it looks >up only items from the left argument so, in a sense, really >only treats the left argument as a vector. The examples on >the definition page should make this a little clearer. > >However, the problem you're attempting to solve, looking up >a scalar in a higher-dimensional array, comes up >frequently. I think of it this way: > (,i. 2 3) i. 4 >4 > 2 3 #: 4 NB. 4 as a base (2,3) number >1 1 NB. gives index into original array. > (<2 3 #: 4) { i. 2 3 >4 > > ixmd=: 4 : '($x)#:y i.~ ,x' NB. Index >multi-dimensionally > (i. 2 3) ixmd 4 >1 1 > >Regards, > >Devon > > >On 5/4/07, Terrence Brannon <[EMAIL PROTECTED]> wrote: >> >> Ok, I'm wondering how I might find the number 4 in a >> rank-2 array using dyadic i. Below are my failed naive >> attempts after reading the section in "Learning J" which >>went over Selecting. >> (i. 2 3) i. 4 >> |rank error >> | (i.2 3) i.4 >> (i. 2 3) i. (3 4 5) >> 1 >> (i. 2 3) i."1 4 >> |syntax error >> | (i.2 3)i."1 4 >> >----------------------------------------------------------- >> ----------- For information about J forums see >>http://www.jsoftware.com/forums.htm > > > >-- >Devon McCormick, CFA >^me^ at acm. >org is my >preferred e-mail >----------------------------------------------------------- >----------- For information about J forums see >http://www.jsoftware.com/forums.htm ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
