How about
([ [^:(0...@]) ".)"1
Henry Rich
On 1/11/2011 10:46 AM, richard.vaug...@us.thewg.com wrote:
> I need a simple utility that will return the numeric value represented by
> a string y, following the rules of dyadic ". except returning the scalar x
> if y is empty. This should be fast since it is to be applied under> to
> large arrays of boxed strings whose exact format cannot be controlled. I
> have observed that if y is preceded by a TAB the result of ". is
> unchanged, and if y is a TAB alone the result is x; therefore adding a TAB
> before (each) y seems to do the trick. But this is not documented in the
> Vocabulary. Can I trust this behaviour to continue in future editions of
> J?
>
> Adding a space would seem more natural but ". treats y that is all spaces
> like an empty vector. Best would be if the left argument to ". had an
> optional second element, specifying the exact number of elements to be
> returned in each row, or default 0 for the present behaviour. Then I
> could force an empty y to receive the padding value 0{x.
>
> Thanks,
>
> Richard Vaughan
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