Moreover, (#:~ $)~ makes for a better smiley.
Am 15.11.20 um 19:23 schrieb Henry Rich:
> On reflection I am not going to implement (4 $. $.) in special code.
>
> The fundamental operation is 'express the numbers in y, which are
> elements of (i. #@, x), as index lists into x'. This is achieved by
>
> (#:~ $)~
>
> y can have any shape. (4 $. $.) works only on an argument that happens
> to have the shape of x. I don't think that's a special case worth
> coding for.
>
> Henry Rich
>
> On 11/13/2020 10:54 PM, Roger Hui wrote:
>> Another candidate is >,{i.&.>$x . (4 $. $.) has the "problem" that
>> indices
>> corresponding to 0 elements are excluded.
>>
>>
>>
>> On Fri, Nov 13, 2020 at 6:59 PM Henry Rich <[email protected]> wrote:
>>
>>> Ric Sherlock has suggested that (4 $. $.) would be an idiom worthy of
>>> special code. I agree & will do it sometime.
>>>
>>>
>> ----------------------------------------------------------------------
>> For information about J forums see http://www.jsoftware.com/forums.htm
>
>
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