Pascal, Your suggestions helped me understand this problem:
pairs=: 13 :'(>:@i. x),"0/>:@i. y'
cb=: 13 :'<"0 >:@i. y'
cb
[: <"0 >:@i.
count=: 13 :'(<@cb)"1 x pairs y'
2 count 2
┌───┬─────┐
│┌─┐│┌─┬─┐│
││1│││1│2││
│└─┘│└─┴─┘│
├───┼─────┤
│┌─┐│┌─┬─┐│
││1│││1│2││
│├─┤│├─┼─┤│
││2│││3│4││
│└─┘│└─┴─┘│
└───┴─────┘
count2=: 13 :'(<@<"0 >:@i. y)"1 x pairs y'
2 count2 2
┌───┬───┐
│┌─┐│┌─┐│
││1│││2││
│└─┘│└─┘│
├───┼───┤
│┌─┐│┌─┐│
││1│││2││
│└─┘│└─┘│
└───┴───┘
┌───┬───┐
│┌─┐│┌─┐│
││1│││2││
│└─┘│└─┘│
├───┼───┤
│┌─┐│┌─┐│
││1│││2││
│└─┘│└─┘│
└───┴───┘
count3=: 13 :'<@([: <"0 >:@i.)"1 x pairs y'
2 count3 2
┌───┬─────┐
│┌─┐│┌─┬─┐│
││1│││1│2││
│└─┘│└─┴─┘│
├───┼─────┤
│┌─┐│┌─┬─┐│
││1│││1│2││
│├─┤│├─┼─┤│
││2│││3│4││
│└─┘│└─┴─┘│
└───┴─────┘
(2 count 2)-:2 count3 2
1
count
[: <@cb"1 pairs
count3
[: <@([: <"0 >:@i.)"1 pairs
count4=: 13 :'([:<([: <"0 [:>:i.))"1 x pairs y'
2 count4 2
┌───┬─────┐
│┌─┐│┌─┬─┐│
││1│││1│2││
│└─┘│└─┴─┘│
├───┼─────┤
│┌─┐│┌─┬─┐│
││1│││1│2││
│├─┤│├─┼─┤│
││2│││3│4││
│└─┘│└─┴─┘│
└───┴─────┘
(2 count3 2)-:2 count4 2
1
cb
[: <"0 >:@i.
count
[: <@cb"1 pairs
count3
[: <@([: <"0 >:@i.)"1 pairs
count4
[: ([: < [: <"0 [: >: i.)"1 pairs
Is there a general preference among programmers for count3 or count4
5!:4 <'count3'
┌─ [:
│ ┌─ <
│ │ ┌─ [:
│ ┌─ @ ─┤ │ ┌─ <
│ │ │ ├─ " ─┴─ 0
──┤ │ └───┤
├─ " ───┤ │ ┌─ >:
│ │ └─ @ ─┴─ i.
│ └─ 1
└─ pairs
5!:4 <'count4'
┌─ [:
│ ┌─ [:
│ ├─ <
│ │ ┌─ [:
│ ┌───┤ │ ┌─ <
│ │ │ ├─ " ─┴─ 0
──┤ │ └────┤
├─ " ───┤ │ ┌─ [:
│ │ └─────┼─ >:
│ │ └─ i.
│ └─ 1
└─ pairs
Linda
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of 'Pascal Jasmin'
via Programming
Sent: Thursday, February 12, 2015 9:13 AM
To: [email protected]
Subject: Re: [Jprogramming] Source of frustration
([: v [: u ]) is almost but not exactly the same as
([: v@:u ])
basically, if u has any adverbs applied to it (such as "1) then those adverbs
also apply to v in v@:u. But don't apply to v in ([: v u)
A good reason for 13 : to have given you what you got is that you explicitly
used @ instead of made just a linear phrase.
________________________________
From: Linda Alvord < <mailto:[email protected]> [email protected]>
To: <mailto:[email protected]> [email protected]
Sent: Thursday, February 12, 2015 3:09 AM
Subject: Re: [Jprogramming] Source of frustration
There have been many explanations of y=how @ works, but here is the question
I really am interested in.
Working code:
(i.4)*/>:i.5
1 2 3 4 5
2 4 6 8 10
3 6 9 12 15
4 8 12 16 20
Simple working definition:
times=: 13 :'(>:i.x)*/>:i.y'
4 times 5
1 2 3 4 5
2 4 6 8 10
3 6 9 12 15
4 8 12 16 20
Definition which also works but seems cumbersome:
times2=: 13 :'(>:@i.x)*/>:@i.y'
4 times 5
1 2 3 4 5
2 4 6 8 10
3 6 9 12 15
4 8 12 16 20
Why couldn't my definition of times be converted to what seems to be the
preferred J version in times2?
times
([: >: [: i. [) */ [: >: [: i. ]
times2
([: >:@i. [) */ [: >:@i. ]
Linda
-----Original Message-----
From: <mailto:[email protected]>
[email protected]
[ <mailto:[email protected]>
mailto:[email protected]] On Behalf Of Linda Alvord
Sent: Monday, February 9, 2015 5:01 PM
To: <mailto:[email protected]> [email protected]
Subject: Re: [Jprogramming] Source of frustration
Here's another example of my suggestion:
These two expressions have the same result.
eb=: 13 :'y $<'' '''
([:<eb)"1(>:i.2),"0/>:i.4
----T-----T-------T---------┐
│--┐│--T-┐│--T-T-┐│--T-T-T-┐│
││ │││ │ │││ │ │ │││ │ │ │ ││
│L--│L-+--│L-+-+--│L-+-+-+--│
+---+-----+-------+---------+
│--┐│--T-┐│--T-T-┐│--T-T-T-┐│
││ │││ │ │││ │ │ │││ │ │ │ ││
│+-+│+-+-+│+-+-+-+│+-+-+-+-+│
││ │││ │ │││ │ │ │││ │ │ │ ││
│L--│L-+--│L-+-+--│L-+-+-+--│
L---+-----+-------+----------
([:<eb)"1(>:i.2),"0/>:i.4
----T-----T-------T---------┐
│--┐│--T-┐│--T-T-┐│--T-T-T-┐│
││ │││ │ │││ │ │ │││ │ │ │ ││
│L--│L-+--│L-+-+--│L-+-+-+--│
+---+-----+-------+---------+
│--┐│--T-┐│--T-T-┐│--T-T-T-┐│
││ │││ │ │││ │ │ │││ │ │ │ ││
│+-+│+-+-+│+-+-+-+│+-+-+-+-+│
││ │││ │ │││ │ │ │││ │ │ │ ││
│L--│L-+--│L-+-+--│L-+-+-+--│ L---+-----+-------+----------
Define each one as I and j
i=: 13 :'(<@eb)"1(>:@i.x),"0/>:@i.y'
j=: 13 :'([:<eb)"1(>:i.x),"0/>:i.y'
Both agree as monads and dyads.
(i 2)-:j 2
1
(2 i 4)-:2 j 4
1
In the interpretation of J, [: is inserted when appropriate.
My question is: "why couldn't both have the same
Definition when trains are involved. It @ is superior, I would suggest the
definition of i
for both.
eb
(<' ') $~ ]
i
[: <@eb"1 ([: >:@i. [) ,"0/ [: >:@i. ]
j
[: ([: < eb)"1 ([: >: [: i. [) ,"0/ [: >: [: i. ]
Linda
eb
(<' ') $~ ]
-----Original Message-----
From: <mailto:[email protected]>
[email protected]
[ <mailto:[email protected]>
mailto:[email protected]] On Behalf Of Kip Murray
Sent: Monday, February 9, 2015 11:00 AM
To: <mailto:[email protected]> [email protected]
Subject: Re: [Jprogramming] Source of frustration
And this:
hh =: 3 : '[: >: i. y'
hh
3 : '[: >: i. y'
hh 4
|domain error: hh
| [:>:i.y
I think Brian's suggestion that you parenthesize the result of 13 : before
applying arguments is the best way of removing your frustration. My point
about parenthsizing [: > i. before applying arguments is specific to verbs
defined by trains.
--Kip
On Monday, February 9, 2015, Linda Alvord < < <mailto:[email protected]>
mailto:[email protected]>
<mailto:[email protected]> [email protected]> wrote:
> How about this:
> h=: 13 :'[:>:i.y'
> h
> [: [: [: >: i.
>
> [: [: [: >: i. 4
> |domain error: scriptd
> | [:[: [:>:i.4
>
> Linda
>
>
> -----Original Message-----
> From: < <mailto:[email protected]>
> mailto:[email protected]>
<mailto:[email protected]>
[email protected] <javascript:;>
> [
> < <mailto:[email protected]%20%3cjavascript:;%3e>
> mailto:[email protected]%20%3cjavascript:;%3e>
<mailto:[email protected]>
mailto:[email protected] <javascript:;>] On
> Behalf Of Brian Schott
> Sent: Monday, February 9, 2015 10:00 AM
> To: Programming forum
> Subject: Re: [Jprogramming] Source of frustration
>
> Linda,
>
> If you are willing to put parentheses around your example verbs --
> with the data outside the parens, you will not get the domain error.
>
> On Mon, Feb 9, 2015 at 9:54 AM, Linda Alvord <[email protected]
> <javascript:;>>
> wrote:
>
> > Suppose: ff=: 13 :'>:i.y'
> > ff
> > >:@i.
> > Then:
> > >:@i.4
> > 1 2 3 4
> > Which is what you want, more than a domain error.
> >
> > Linda
> >
> > --
> (B=)
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