0. Do you care to explain how this WL program works?
symSoc = society /.
{a_Integer, b_} :> {a, Union[b, Cases[society, {x_, {___, a, ___}} :> x]]}
1. How well does it perform if "society" has 10 million members?
On Thu, Sep 12, 2013 at 9:37 PM, Richard Gaylord <[email protected]>wrote:
> roger:
>
> thanks very much for your response. the code in my lecture notes does
> include the case where each person is a member of his network.
>
> when i look at your code , i realize that i would be best to keep using the
> Wolfram language (WL) rather than learn to master J as you have (of course
> that's understandable since you created J ). i am too set in my programming
> ways to learn a new language at this point unless it offers me something
> very substantially better than WL.
>
> also, i happen to truly love WL and have been a WL evangelist for 25 years,
> using it in my four books and teaching WL with great pleasure to over a
> thousand students at university in a variety of fields (physics, chemistry,
> biology, sociology and economics/business) and in industry and government,
> how WL works in 6.5 hrs. of lecture (sometimes given in four 90 minute
> classroom increments and sometimes in one day-long lecture).
>
> you know, i first learned WL
>
> - which has been unfortunately been called Mathematica which is the
> software that is built upon WL because stephen wolfram took 25 years before
> announcing this spring the imminent release of WL as a stand-alone app to
> run on computers and mobile devices (as J already does) -
>
> by reading "Life; Nasty, Brutish and Short" and thereby learning array
> processing. and implementing it in WL while also incorporating anonymous
> functions (J was not yet created) and nested function calls and eventually
> rules and pattern matching. To this day, i consider consider myself an
> APL'er by nature who delights in the creation of unreadable one-liner code
> LOL. but i do it in WL which is far easier for me to read and work with
> (and i actually first became aware of APL through stephen's Mathematica
> book).
>
> i also recall returning to the US from an APL meeting in Toronto (where i
> gave a tutorial on WL) sitting next to Arthur Whitney on the plane,
> running side-by-side comparisons of the speed of my writing and running
> pieces of code in WL with Arthur's doing the same with his just created K
> language on our respective MacBooks.
>
> As a scientist (i'm a theoretical condensed soft matter physicist), i have
> available a community of well over a million users of Mathematica to teach
> WL to and to learn from and that's too great resource for me to not use (if
> i could get them each to buy at least one of my books, i'd be financially
> set LOL).
>
> so i guess i'll continue to use WL and to wear my custom-made black WL icon
> logo T-shirt.
>
> richard
>
>
> On Thu, Sep 12, 2013 at 7:53 PM, Roger Hui <[email protected]
> >wrote:
>
> > If we modify the input slightly, by requiring that each person is a
> member
> > of his own network (i.e. the reflexive closure), then the computation can
> > be more concise:
> >
> > c=: 0;1 5 7;2 ;3;4 1 2;5 2 7;6 2;7 8;8 5
> > c
> > ┌─┬─────┬─┬─┬─────┬─────┬───┬───┬───┐
> > │0│1 5 7│2│3│4 1 2│5 2 7│6 2│7 8│8 5│
> > └─┴─────┴─┴─┴─────┴─────┴───┴───┴───┘
> > <@~././ |: (,|."1) (I.#&>c),.;c
> > ┌─┬───────┬───────┬─┬─────┬─────────┬───┬───────┬─────┐
> > │0│1 5 7 4│2 4 5 6│3│4 1 2│5 2 7 1 8│6 2│7 8 1 5│8 5 7│
> > └─┴───────┴───────┴─┴─────┴─────────┴───┴───────┴─────┘
> >
> >
> >
> >
> >
> > On Thu, Sep 12, 2013 at 4:27 PM, Roger Hui <[email protected]
> > >wrote:
> >
> > > s=: '';5 7;'';'';1 2;2 7;2;8;5
> > > s
> > > ┌┬───┬┬┬───┬───┬─┬─┬─┐
> > > ││5 7│││1 2│2 7│2│8│5│
> > > └┴───┴┴┴───┴───┴─┴─┴─┘
> > > j -.&.>~ </./ |: (,.~j),(,|."1) (;s),.(#&>s)#j=. i.#s
> > > ┌┬─────┬─────┬┬───┬───────┬─┬─────┬───┐
> > > ││4 5 7│4 5 6││1 2│1 8 2 7│2│1 5 8│7 5│
> > > └┴─────┴─────┴┴───┴───────┴─┴─────┴───┘
> > >
> > > (;s),.(#&>s)#j are the relationships in ordered pair form; (,|."1) of
> > that
> > > catenates the reversed ordered pairs; and the rest of the code puts the
> > > information back into the form in which s is specified.
> > >
> > > Repeated application of this processes is the transitive closure
> (friend
> > > of my friend is also my friend, *ad infinitum*).
> > >
> > >
> > >
> > > On Thu, Sep 12, 2013 at 3:44 PM, Richard Gaylord <[email protected]
> > >wrote:
> > >
> > >> here's some code in the Wolfram Programming Language (the language
> > >> underlying Mathematica) illustring the use of pattern matching.
> > >>
> > >>
> > >>
> > >> Society is a list of the attribute lists of people. As an
> illustration,
> > we
> > >> will create a society consisting of eight people, each with two
> > >> attributes.
> > >> In each person's attribute list,
> > >> the first element (which is a number) represents the person's name ,
> > >>
> > >> the second element which is a list of numbers) is a list of the names
> of
> > >> the members of the person's social network.
> > >>
> > >>
> > >> society = {{1, {5, 7}},
> > >> {2, {}},
> > >> {3, {}},
> > >> {4, {1, 2}},
> > >> {5, {2, 7}},
> > >> {6, {2}}},
> > >> {7, {8}},
> > >> {8, {5}}}
> > >>
> > >> We can modify society so that anyone who is in another person's social
> > >> network includes that person in their own social network (i.e.,
> > reciprocal
> > >> social connections).
> > >>
> > >> symSoc = society /.
> > >> {a_Integer, b_} :> {a, Union[b, Cases[society, {x_, {___, a, ___}} :>
> > >> x]]}
> > >>
> > >> symSoc = {{1, {4, 5, 7}},
> > >> {2, {4, 5, 6}},
> > >> {3, {}},
> > >> {4, {1, 2}},
> > >> {5, {1, 2, 7, 8}},
> > >> {6, {2}},
> > >> {7, {1, 5, 8}},
> > >> {8, {5, 7}}}
> > >>
> > >> how would this be done in J?
> > >>
> > >> note: a pdf of the note set on the Wolfram Language in which the
> > >> expressions for society and symSoc appear on p. 42 can be downloaded
> at
> > >>
> > >> http://library.wolfram.com/infocenter/MathSource/5216
> >
>
> --
>
> *"Those who would sacrifice freedom for security deserve neither." -
> Benjamin Franklin*
>
>
> *"I think that the very notion that equations are a good approach to
> describing the natural world is a little bizarre."
> - Stephen Wolfram*
>
> *
> *
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