Hi, for some examples of J coding you can look at : :
https://github.com/jitwit/aoc I found his site while playing at Advent of Code. Jimmy On Sun, Dec 6, 2020 at 7:44 PM bill lam <[email protected]> wrote: > you can use OOP class, object. They are implemented with locale. This is > close enough to C structure. See labs. > > > > On Mon, Dec 7, 2020, 5:53 AM emacstheviking <[email protected]> wrote: > > > Rob and Raul.. > > > > Thanks chaps for the comments...the first thing I need to do is write > > -something- that does something and then go from there. > > It's not really a maths problem... well, in a way everything is maths I > > guess but I am wanting to learn J and to write a game with it and that's > > pretty much it. > > > > I'll post some progress somewhere someday... > > > > Thanks again > > Sean > > > > > > On Sun, 6 Dec 2020 at 21:41, 'Rob Hodgkinson' via Programming < > > [email protected]> wrote: > > > > > Sean, the data structures in J work brilliantly for mathematical array > > > type problems. > > > > > > When the data framework you are seeking is more “structured” (akin to > > > Tables and Columns, or Keys and Values), then a more suited structure > > might > > > require “jdb” for example (which makes use of boxing “tuples”). > > > This is a J compatible structured database for tables and columns. > > > > > > It really depends on the problem you are solving, for example for > Advent > > > of Code or other coding challenges they are usually mathematical in > > nature > > > and the J arrays are perfect, as they can be rectangular arrays > (matrices > > > etc) or nested arrays (boxed) so there is a lot of flexibility. > > > > > > With that in mind, I suggest learn the tools and then consider the > > > structure depending on the nature of the problem, but they are pretty > > well > > > all there for you to use. > > > > > > HTH Rob > > > > > > > On 7 Dec 2020, at 7:50 am, emacstheviking <[email protected]> wrote: > > > > > > > > Hauke, > > > > Thanks for your comments. I have been scribbling notes on howto go > > about > > > > it, my initial thoughts are that I need: > > > > > > > > genstar =: 3 : 0 > > > > generates an array of random numbers: initial x, initial y, dy, > type > > > > > > > > updstar =: 3 : 0 > > > > in-place updates y by adding dy*timer interval > > > > if y is off screen then randomly reset this entry with y=0 > > > > > > > > Ha! This is going to be a lot of fun... > > > > > > > > > > > > > > > > > > > > On Sun, 6 Dec 2020 at 20:36, Hauke Rehr <[email protected]> > > wrote: > > > > > > > >> If the atoms of x, y and dy are all numbers (or tuples thereofª), > > > >> you can use a 3(or moreª)×(whatever common shape they have) array. > > > >> Index into them along the correct axes, and you’ll get > > > >> back (or modify) a triplet (or triplets) (again, or moreª). > > > >> > > > >> And updating ought to be done in place as much as possible. > > > >> You don’t do updating most of the time, but when you need to, > > > >> do it in place if at all possible. > > > >> You’re guaranteed to work in place if you immediately assign > > > >> back to the name of the structure you amend, for example. > > > >> Also, take a look at the special combinations. > > > >> Personally, I avoid boxing as much as possible. > > > >> > > > >> Then again, that’s just my thoughts and I’m far from > > > >> as experienced as the average person on this list, I guess. > > > >> > > > >> Am 06.12.20 um 21:13 schrieb emacstheviking: > > > >>> What's the conventional wisdom / best practice on defining data > > > >> structures > > > >>> for an application? > > > >>> > > > >>> Given there is no explicit keyword/operator support like C (typdef, > > > >>> struct) is it merely a case of convention and using boxed > > structures. > > > I > > > >>> have read several operators that can modify structures both as new > > > >> aliased > > > >>> copies and in-place modifications but I do not have the experience > > > with J > > > >>> to know what's efficient at run time in time / memory etc. > > > >>> > > > >>> My specific use case is that of a vertically scrolling star > field... > > I > > > >>> intend to recreate and hopeful extend the tiny little game I wrote > > but > > > >>> never finished, screenshot here: > > > >>> http://seancharles.xyz/posts/2019-10-06-all-at-c.html > > > >>> > > > >>> In that I had a struct that had the x, y, dy and type values but it > > > seems > > > >>> to me that given that J is all about arrays, it might be more > > efficient > > > >>> using parallel arrays i.e. x array, y array, dy array etc. > > > >>> > > > >>> Also, given that the state is being updated in a tight event loop > > using > > > >> the > > > >>> time differential between frames to calculate the step motion (i.e. > > CPU > > > >>> speed independently), what are your thoughts on immutable updates > > > >> producing > > > >>> new arrays or updating in place ? > > > >>> > > > >>> Thanks, > > > >>> Sean. > > > >>> > > ---------------------------------------------------------------------- > > > >>> For information about J forums see > > http://www.jsoftware.com/forums.htm > > > >>> > > > >> > > > >> -- > > > >> ---------------------- > > > >> mail written using NEO > > > >> neo-layout.org > > > >> > > > >> > ---------------------------------------------------------------------- > > > >> 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 > > > ---------------------------------------------------------------------- > For information about J forums see http://www.jsoftware.com/forums.htm > ---------------------------------------------------------------------- For information about J forums see http://www.jsoftware.com/forums.htm
