I guess the input needs to be
animals ,: ids
so...
ai =: animals ,: ids
f2 =: (1&{) f (0&{) NB. f same as previous answer.
f2 ai
I guess that's not really "one expression" now, so
f2 =: 1&{ (((1 ,~ #) $ ])@:~.@:] ,. ]/.~) 0&{
--------------------------------------------
On Fri, 3/4/16, 'Jon Hough' via Programming <[email protected]> wrote:
Subject: Re: [Jprogramming] J Challenge
To: [email protected]
Date: Friday, March 4, 2016, 6:34 PM
I don't think for a minute that this
will be the most terse or most elegant but this is what I
got:
animals =:
'bird';'cow';'cow';'dog';'cow';'cow';'cow';'bird';'dog';'cat';'dog';'pig';'dog';'bird';'pig'
ids =: 1;2;3;4;5;6;7;8;9;10;11;12;13;14;15
f =: (((1,~ #) $])@:~.@:]) ,. (]/.)~
ids f animals
--------------------------------------------
On Fri, 3/4/16, Skip Cave <[email protected]>
wrote:
Subject: [Jprogramming] J Challenge
To: "[email protected]"
<[email protected]>
Date: Friday, March 4, 2016, 6:01 PM
Well, the format of that last post
was a bit messy. Here's a second try:
The
animal control officer wants to keep track of the
animals
in a city.
The officer tags all the animals with a serial number.
He keeps a list of all the animals he has tagged, along
with
each serial
number.
list
┌────┬───┬───┬───┬───┬───┬───┬────┬───┬───┬───┬───┬───┬────┬───┐
│bird│cow│cow│dog│cow│cow│cow│bird│dog│cat│dog│pig│dog│bird│pig│
├────┼───┼───┼───┼───┼───┼───┼────┼───┼───┼───┼───┼───┼────┼───┤
│1 │2 │3 │4
│5 │6 │7
│8 │9 │10 │11 │12 │13
│14 │15 │
└────┴───┴───┴───┴───┴───┴───┴────┴───┴───┴───┴───┴───┴────┴───┘
The officer now wants to make a second list showing each
type
of animal along with all the serial numbers tagged for
each
animal.
list2
┌────┬──┬──┬──┬──┬─┐
│bird│1 │8 │14│ │ │
├────┼──┼──┼──┼──┼─┤
│cow │2 │3 │5 │6 │7│
├────┼──┼──┼──┼──┼─┤
│dog │4 │9 │11│13│ │
├────┼──┼──┼──┼──┼─┤
│cat │10│ │ │ │ │
├────┼──┼──┼──┼──┼─┤
│pig │12│15│ │ │ │
└────┴──┴──┴──┴──┴─┘
What is the shortest J expression to generate list2?
(Tacit would be nice)
Skip Cave
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