Monad=: :[: RightId=: @] example1=: >: Monad example2=: >: RightId example1 2 3 5 7 3 4 6 8 example2 2 3 5 7 3 4 6 8 0 example1 2 3 5 7 |domain error: example1 | 0 example1 2 3 5 7 0 example2 2 3 5 7 3 4 6 8
In other words, :[: produces a verb with an empty dyadic domain, while @] produces a verb whose dyadic definition which ignores its left argument and otherwise matches its monadic definition. Thanks, -- Raul On Mon, Mar 3, 2014 at 3:19 PM, Pascal Jasmin <godspiral2...@yahoo.ca> wrote: > interesting implementation. > > Could you please explain > > Monad =: :[: > > > ? > is it equivalent in use to @:] ? > > > ----- Original Message ----- > From: David Lambert <b49p23t...@stny.rr.com> > To: programming <programm...@jsoftware.com> > Cc: > Sent: Monday, March 3, 2014 2:29:35 PM > Subject: [Jprogramming] Dictionary data type > > The standard answer to "Does J have a dictionary data type?" seems to be > "Use symbols." > (Two other answers today recommend locales.) To which we ask, "How do > we use symbols?" Given that I may have overlooked a lab, I'll show my > effort. My goal is to maintain a database of probabilities written in a > standard long form. "P(a)" is an invalid j pronoun. > I solve this with string keys mapped to symbols. J implements symbols > with red-black trees. They're quickly accessed. The symbol values are > indexes into a boxed list of values. This is my dict.ijs file. The > note at the end gives example use. I've fancifully called the wikipedia > "Encyclopedia Galactica", so the example refers to that of > http://en.wikipedia.org/wiki/Posterior_probability . > > coclass 'dict' > > NB. implement associative array > > VALUE =: 0$a: > > Monad =: :[: > symbol =: s:^:('literal'-:datatype) Monad > > NB. index'`literal' > index =: 6&(s: symbol) Monad > > NB. may fetch multiple items, returns boxed items > get =: (index { ".@:('VALUE'"_)) Monad > > NB. may fetch multiple items, opens the boxes! > openGet =: >@:get Monad > > put =: dyad define > KEY =. symbol y > if. 1 (= #) KEY do. > V =. < x > else. > assert KEY =&# x > V =. ;/ x > end. > I =. index KEY > L =. >: >./ I > if. L (> #) VALUE do. VALUE =: (+:L){.VALUE end. > VALUE =: V I} VALUE > KEY > ) > > cutSTRING =: #@:[ }.&.> , <;.1~ [ E. , > assert ((,0);4 5 6 7) -: 1 2 3 cutSTRING i.8 > > embed =: >@:{.@:[ , ] , >@:{:@:[ > assert 'bats' -: 'bs'embed'at' > > Filter =: (#~`)(`:6) > assert 0 1 2 -: <&3 Filter i.6 > assert 'SUPPER'-:<&(a.i.'a')Filter&.:(a.&i.)'SelectUPPERcase' > > getAllSymbols =: _6 s: [: i. s:~@:0: > > mp =: ($: |:@:+) :(+/ .*) > > NB. probability of pants, from law of total probability > > NB. y is the value for which to compute total probability > NB. totalProbability =: openGet :: (verb define) > > NB. y is the value for which to compute total probability > totalProbability =: verb define > NB. returns P(y|CONDITIONi)P(CONDITIONi) > assert 'P()' -: 1 2 _1 { y > CONDITIONAL_GOAL =. '|'_1}y > SYMBOLS =. getAllSymbols'' > LITERALS =. ": SYMBOLS > A =. ('`'~:{.&>) Filter CONDITIONAL_GOAL cutSTRING LITERALS > B =. ({.~i.&')')&.>A NB. B are boxes of conditionals. > PYI =. openGet;('`P(';')')&embed&.>B > PXYI =. openGet;(CONDITIONAL_GOAL;')')&embed&.>B > assert PYI -:&# PXYI > y put~ PYI mp PXYI > openGet y > ) > > Note 'Encyclopedia Galactica: posterior probability' > NB. wikipedia example on Tue Oct 22 15:18:33 EDT 2013 > load'dict.ijs' > D=:conew'dict' > > NB. probability student is a boy, complementary girl > ((,-.)0.6)put__D'`P(B)`P(G)' > > NB. probability wearing pants given sex > 1 0.5 put__D'`P(P|B)`P(P|G)' > > NB. compute and store probability to observe pants. > EMPTY [ totalProbability__D'`P(P)' > > NB. Finally, Bayes Law. Find P(G|P). > %/ ; openGet__D'`P(P|G)`P(P)`P(G)' > 0.25 > ) > >> Date: Mon, 3 Mar 2014 09:06:00 -0600 >> From: Yike Lu<yikelu.h...@gmail.com> >> To:programm...@jsoftware.com >> Subject: Re: [Jprogramming] Sorry state of slow parsing of JSON in J >> Message-ID: >> <CAO=ap+cujrjnshftlhipnyzrk2mfrav_wak+-qzbl5vigee...@mail.gmail.com> >> Content-Type: text/plain; charset=UTF-8 >> >> A tangential but related question: does J have a dictionary data type? >> Where can I read about it? >> >> Thanks. > ---------------------------------------------------------------------- > 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
