My strategy in efficiently converting a lot of dates: restrict to the nub. No one has more than a few thousand dates. Just my 2c.
R.E. Boss > -----Original Message----- > From: Programming <[email protected]> On > Behalf Of Jimmy Gauvin > Sent: donderdag 5 april 2018 04:40 > To: [email protected] > Subject: Re: [Jprogramming] converting date number to iso 8601 > > I played around with this a bit more and arrived at something much faster > than my initial approach which is in fact pretty slow. > > Raul : > > 6!:2 'daten28601 5e6 $ 20180102' > 1.40457 > > My first take : > 6!:2 ' ff("0) 5e6 $ 20180102' > 87.6379 > > My second take: > > > 6!:2 'fff("0) 5e6 $ 20181122' > > 5.19095 > > > > ff =: 3 : '''-'' 4 7 } 1 1 1 1 2 1 2 1": 10#.inv y' > > fff =: 3 : '''0123456789-''{~0 0 0 0 10 0 0 10 0 0+10 10 10 10 1 10 10 > 1 10 10#: y' > > > > > A variant on Raul's method is to use expand rather than copy (expand is > slower though). > > b&#^:_1 where b is a boolean list is *Expand* (whose fill atom f can be > specified by *fit*, b&#^:_1!.f or #^:_1!.f ) > > > ]DYP=: -. (i.10)e.4 7 > 1 1 1 1 0 1 1 0 1 1 > daten28602=: DYP #^:_1!.'-'"1 ":@,. > > > > > On Wed, Apr 4, 2018 at 7:08 PM, Joe Bogner <[email protected]> wrote: > > > Raul, that is great. I have used # thousands of times probably but > > never encountered this use > > > > "The complex left argument a j. b copies a items followed by b fills. > > The fit conjunction provides specified fills, as in #!.f ." > > > > http://www.jsoftware.com/help/dictionary/d400.htm > > > > > > I'm glad I asked because something simple like this uncovers new ways > > of thinking > > > > Jimmy - Same goes for yours too. Raul's approach is much speedier > > however yours highlighted an interesting technique for the future. > > > > Thank you both > > > > On Wed, Apr 4, 2018 at 6:18 PM, Jimmy Gauvin <[email protected]> > > wrote: > > > This might be fast : > > > > > > '-' 4 7 } 1 1 1 1 2 1 2 1 ": 10#.inv 20170209 > > > > > > 2017-02-09 > > > > > > > > > On Wed, Apr 4, 2018 at 6:04 PM, Raul Miller <[email protected]> > > wrote: > > > > > >> Here's one approach: > > >> > > >> > > > > DXP=: (8#1) j. (i.8)e.3 5 > > >> > > > > daten28601=: DXP #!.'-'"1 ":@,. > > >> > > >> > > > > 6!:2 'daten28601 (5e6 1 $ 20180102)' > > >> 0.659381 > > >> > > >> -- > > >> Raul > > >> > > >> On Wed, Apr 4, 2018 at 5:56 PM, Joe Bogner <[email protected]> > wrote: > > >> > I'm curious if there is a speedier way to convert a date stored > > >> > as a number like 20180101 or 20170228 to the ISO 8601 equivalent: > > >> > > > >> > This does OK > > >> > > > >> > datenumToISO =: 3 : 0 > > >> > (4&{. , '-' , 2&{.@(4&}.) , '-' , _2&{.)"1 ": y > > >> > ) > > >> > > > >> > datenumToISO 20180101 > > >> > 2018-01-01 > > >> > datenumToISO 20180228 > > >> > 2018-02-28 > > >> > > > >> > > > >> > But is slower than I'd like ... no big deal but just curious > > >> > > > >> > 6!:2 'datenumToISO (5e6 1 $ 20180102)' > > >> > 4.29083 > > >> > > > >> > sprintf is slow > > >> > > > >> > dateNumToISO2 =: 3 : 0 > > >> > '%d-%02d-%02d' sprintf ,:(0 100 100 #: y) > > >> > ) > > >> > > > >> > (6!:2) 'dateNumToISO2 (1e5 # 20180102)' > > >> > 2.34002 > > >> > (6!:2) 'dateNumToISO2 (1e6 # 20180102)' > > >> > 25.4977 > > >> > > > >> > > > >> > 8!:2 shows promise but I can't figure out the formatting string > > >> > to add a leading zero if it's possible > > >> > > > >> > (6!:2) '8!:2 (0 100 100 #: (5e6 # 20180102))' > > >> > 1.4853 > > >> > > > >> > 'q<->,q<->,d' 8!:2 (0 100 100 #: (1 # 20180102)) > > >> > 2018-1-2 > > >> > ------------------------------------------------------------ > > ---------- > > >> > 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
