Re: [Jprogramming] Implementing a tacit filter function

Johann Hibschman wrote: Part of the problem here is that filter is not a verb; it's an *adverb*. That's the key insight one needs, yes. I'm just a beginner myself, so I'm not sure that this can't be done tacitly, but an explicit version is: filter =: 1 : '#~ x' Some beginner advice here.

Re: [Jprogramming] Splitting an integer into its digits

Thanks Bill David, And thanks for NOT sending the spoiler, Bill, I'd rather work on it some more for now. The tip re @: was just what I was after, I think. I haven't had occasion to use the f. adverb yet, I'll go read it up now. On Sat, 2010-08-28 at 11:15 +0800, bill lam wrote: to get the

[Jprogramming] Rank zero append (,0)

'',1 2 3 1 2 3 NB. OK '',0 [1 2 3 |length error | '',0[1 2 3 NB. Is this because there are NO atoms in LH argument? NB. I would have preferred to have seen 1 2 3 1 2 3,0/ 4 5 6 1 4 1 5 1 6 2 4 2 5 2 6 3 4 3 5 3 6 NB. OK '',0/ 4 5 6 NB. I would have preferred to

Re: [Jprogramming] Rank zero append (,0)

As http://www.jsoftware.com/help/primer/agreement.htm states in the last paragraph: (...) one frame must be a prefix of the other (...) The frames of '',0 [1 2 3 are 0 and 3, since 0=$'' and 3=$1 2 3 . Since 0 is not a prefix of 3 you get a length error. See also

Re: [Jprogramming] Splitting an integer into its digits

Oops, before we go any further, I've stumbled on a real gotcha e.g. digits 1974 123 1 9 7 4 0 1 2 3 now, when I apply (+!) to that lot, it is also applied to the leading zero of 0123 - which, of course, leads to a wrong result when summed. AAARGH! Never mind that when I try to sum with /+

Re: [Jprogramming] Splitting an integer into its digits

From: Alex Gian Sent: Sunday, 29 August 2010 00:23 Oops, before we go any further, I've stumbled on a real gotcha e.g. digits 1974 123 1 9 7 4 0 1 2 3 now, when I apply (+!) to that lot, it is also applied to the leading zero of 0123 - which, of course, leads to a wrong result

Re: [Jprogramming] Splitting an integer into its digits

It is important to note that when changing rank there are three numbers involved. By only giving one number it sets all number to the same (10#.inv0) b. 0 0 0 0 The first number being the monadic case and the other two for left and right of the dyadic case 2010/8/28 Sherlock, Ric

Re: [Jprogramming] Splitting an integer into its digits

From: Sherlock, Ric Sent: Sunday, 29 August 2010 00:56 From: Alex Gian Sent: Sunday, 29 August 2010 00:23 Oops, before we go any further, I've stumbled on a real gotcha e.g. digits 1974 123 1 9 7 4 0 1 2 3 now, when I apply (+!) to that lot, it is also applied to the

Re: [Jprogramming] Splitting an integer into its digits

@ Ric Bjorn, re rank Thanks guys, I actually knew I had to use 0 but I was messing up the syntax somewhere, your examples and commentary are making it a whole lot easier. -- For information about J forums see

Re: [Jprogramming] Splitting an integer into its digits

Thanks a lot for that Ric. I actually managed to get as far as this: digits =. 10#.inv fp1 =. +! spsum =. +/ @ |: @ fp1 @ digits special =. = spsum (#~ special)i.10 which gave me 85837 correctly also, (#~ special)i.100 41086 408297 gives the correct larger number in very acceptable

Re: [Jprogramming] Splitting an integer into its digits

From: Alex Gian Sent: Sunday, 29 August 2010 02:01 Thanks a lot for that Ric. I actually managed to get as far as this: digits =. 10#.inv fp1 =. +! spsum =. +/ @ |: @ fp1 @ digits special =. = spsum (#~ special)i.10 which gave me 85837 correctly also, (#~

Re: [Jprogramming] Splitting an integer into its digits

I expect the following to be faster: Apply digits to the whole array at once, and also apply (+!) to the result of that. But before you apply +/1, do something about the elements corresponding to leading 0 digits, e.g. (* -.@:(*/\1)@:(0=)) . - Original Message - From: Sherlock, Ric

Re: [Jprogramming] Splitting an integer into its digits

(* +./\1@(0~:)) - Original Message - From: Roger Hui rhui...@shaw.ca Date: Saturday, August 28, 2010 8:26 Subject: Re: [Jprogramming] Splitting an integer into its digits To: Programming forum programming@jsoftware.com I expect the following to be faster: Apply digits to the whole

Re: [Jprogramming] Rank zero append (,0)

I find your explanation very helpful, especially because of the links you have given to the primer, which I had not studied carefully. Refer to the following link, please, where we read, For a dyad the left rank of the verb and the rank of the left argument determine the frame of the left

Re: [Jprogramming] Rank zero append (,0)

I see that the example I meant to show literal arguments was not included so I am adding it now, though it is certainly not noteworthy. ''(,0) frame '123' ┌─┬─┐ │0│3│ └─┴─┘ And the next examples show a monadic verb and a dyadic verb with literal arguments.   + frame 2 3 4 ┌─┐ │3│