Ah, performance. Sorry, that's not my department (too many stairs down off this
damn ivory tower).
Perhaps R.E. Boss or Roger will chime in :)
I'll post a correction to the { approach later tonight, just for the sake of
completeness.
> On Mar 30, 2014, at 6:13 PM, EelVex <[email protected]> wrote:
>
> The question is "how to do it efficiently", mostly in time, ideally in
> space too.
>
> X {"0 1"_1 _ A
>
> is not as good as your other suggestion (and it's not working the same way).
>
>
>
>
>> On Mon, Mar 31, 2014 at 1:00 AM, Dan Bron <[email protected]> wrote:
>>
>> If the question is just "how to get it done", rather than "how to get it
>> done using } tacitly", then I suggest straightforward selection at rank.
>>
>> X {"0 1"_1 _ A
>> 0 17 28 39 42 52 65 75 85 93
>> 8 10 20 35 49 56 64 70 86 94
>> 9 18 25 37 44 50 61 72 87 99
>> 3 12 21 32 49 55 63 79 86 99
>> 0 16 23 32 49 51 67 73 85 92
>> ...
>>
>> -Dan
>>
>> PS: Because i haven't seen my previous message on this come back yet, the
>> answer using } tacitly and fixing A is:
>>
>> X=: 50 10 ?@$ 10
>> A=:i. 10 10
>> ]`(A"_)}"_1 X
>> 0 71 82 93 24 25 56 57 58 39
>> 80 1 2 53 94 65 46 7 68 49
>> 90 81 52 73 44 5 16 27 78 99
>> 30 21 12 23 94 55 36 97 68 99
>>
>>
>>>> On Mar 30, 2014, at 5:46 PM, Brian Schott <[email protected]>
>>> wrote:
>>>
>>> Are you familiar with J's Oblique? Your mention of diagonals suggest it
>> to
>>> me.
>>>
>>> http://jsoftware.com/help/dictionary/d421.htm
>>>
>>>
>>>
>>> --
>>> (B=)
>>> ----------------------------------------------------------------------
>>> 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
----------------------------------------------------------------------
For information about J forums see http://www.jsoftware.com/forums.htm
