It is called interval index (dyad I.), please see help
documentation for detail.
2.5 5 7.5 I. 1 3 3 3 4 7 7 8 8 9
0 1 1 1 1 2 2 3 3 3
#/.~ 2.5 5 7.5 I. 1 3 3 3 4 7 7 8 8 9
1 4 2 3
Вс, 08 май 2016, dahn oak написал(а):
> Hello, I want to mimic this Mathematica code:
>
> BinCounts[x, {div}]
>
> It returns an array where i-th element is a count of elements in x that
> belongs to interval [div_i, div_i+1).
> I've succeeded, but want to know if my soulution is adequate enough in terms
> of J programming style. Here it is:
>
> (/:~ x) ((</ }.) +/@:*. (>:/ }:)) div
>
> Example:
>
> ] x =: /:~ ? 10 # 10
> 1 3 3 3 4 7 7 8 8 9
> x ((</ }.) +/@:*. (>:/ }:)) 0 2.5 5 7.5 _
> 1 4 2 3
>
> It's a histogram
> 1 = # 1 NB. (>:&0 *. <&2.5)
> 4 = # 3 3 3 4 NB. (>:&2.5 *. <&5 )
> 2 = # 7 7 NB. (>:&5 *. <&7.5)
> 3 = # 8 8 9 NB. (>:&7.5 *. <&_ )
>
> The main concern is that the }. and {: makes array copies, as far as I know.
> Can I do better, more J-ish solution?
>
> ──
> dahn oak <[email protected]>
> ----------------------------------------------------------------------
> For information about J forums see http://www.jsoftware.com/forums.htm
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regards,
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