NB. Explain behavior of
r =: [: |. 3 $ |.
NB. Compare steps for r 0 1 with steps for r i. 2 3 4 .
NB. First
r 0 1
1 0 1
NB. What happens is
|. 0 1 NB. Reverse 0 1
1 0
3 $ 1 0 NB. Select from 1 0 1 0 1 0 ... until 3 have been chosen
1 0 1
|: 1 0 1 NB. Reverse 1 0 1
1 0 1
NB. Now look at
i. 2 3 4 NB. Items are two 3 by 4 arrays, think array0 and array1
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
NB. When we do r i. 2 3 4 what happens is
|. i. 2 3 4 NB. Reverse the two arrays
12 13 14 15
16 17 18 19
20 21 22 23
0 1 2 3
4 5 6 7
8 9 10 11
3 $ |. i. 2 3 4 NB. Select 3 from array1 array 0 array 1 array 0 ...
12 13 14 15
16 17 18 19
20 21 22 23
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
|. 3 $ |. i. 2 3 4 NB. reverse the selected arrays
12 13 14 15
16 17 18 19
20 21 22 23
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
NB. Thus,
r i. 2 3 4
12 13 14 15
16 17 18 19
20 21 22 23
0 1 2 3
4 5 6 7
8 9 10 11
12 13 14 15
16 17 18 19
20 21 22 23
On 11/22/2011 8:54 PM, Linda Alvord wrote:
> Here's a simple translation, but both it and the original have the same
> peculiarities.
>
> ranks =: 3 : '3$&.|.y'
> ranks
> 3 : '3$&.|.y'
>
> ranks2 =: 13 : '3$&.|.y'
> ranks2
> 3 $&.|. ]
>
> r=: 13 :'|.(|. 3) $|.y'
> r
> [: |. 3 $ |.
>
> 5!:4<'ranks'
> -- 3
> - : -+- ,:'3$&.|.y'
>
> 5!:4<'ranks2'
> -- 3
> │ -- $
> --+-&. -+- |.
> L- ]
>
> 5!:4<'r'
> -- [:
> +- |.
> --+ -- 3
> L----+- $
> L- |.
>
> ranks 2
> 2 2 2
> ranks 2 3
> 3 2 3
> ranks i.2 3 4
> 12 13 14 15
> 16 17 18 19
> 20 21 22 23
>
> 0 1 2 3
> 4 5 6 7
> 8 9 10 11
>
> 12 13 14 15
> 16 17 18 19
> 20 21 22 23
>
>
>
> r 2
> 2 2 2
> r 2 3
> 3 2 3
> r i.2 3 4
> 12 13 14 15
> 16 17 18 19
> 20 21 22 23
>
> 0 1 2 3
> 4 5 6 7
> 8 9 10 11
>
> 12 13 14 15
> 16 17 18 19
> 20 21 22 23
>
> I have't followed some of the later ways to find rank. My question is what
> happened here. It seemed like a simple J expression.
>
> Thanks
>
> Linda
>
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of Kip Murray
> Sent: Monday, November 21, 2011 6:40 AM
> To: Programming forum
> Subject: Re: [Jprogramming] 21 November ranks challenge in Simple J
>
> It is 21 November, solutions are welcome.
>
> On 11/18/2011 11:33 AM, Kip Murray wrote:
>> Please wait until Monday 21 November to post solutions.
>>
>> From the Rank u"n page in the Vocabulary:
>>
>> The verb u"n applies u to each cell as specified by the rank n . The
>> full form of the rank used is 3$&.|.n . For example, if n=:2 , the three
>> ranks are 2 2 2 , and if n=: 2 3, they are 3 2 3 .
>>
>> The challenge: rewrite verb
>>
>> ranks =: 3 : '3$&.|.y'
>>
>> using a train with no conjunctions.
>>
>> ranks 2
>> 2 2 2
>> ranks 2 3
>> 3 2 3
>>
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