Marshall,
Wow! that is neat! I hadn't really understood dyadic I. but this forced me
to try to understand it:
8 100 (]#~1=I.) 2 10 45 300
10 45
8 100 I. 2 10 45 300
0 1 1 2
1 = 8 100 I. 2 10 45 300
0 1 1 0
(1 = 8 100 I. 2 10 45 300) # 2 10 45 300
10 45
8 100 I. 2 10 45 300
0 1 1 2
1 8 100 I. 2 10 45 300
1 2 2 3
1 8 100 I. 2 10 45 300 450
1 2 2 3 3
1 8 100 350 I. 2 10 45 300 450
1 2 2 3 4
1 8 100 350 I. 300 2 45 10 450
3 1 2 2 4
So now I'm getting a feel for I. Reading the terse Vocabulary description
of dyadic I. didn't help much in making the I. functionality clear, at
least for me. The NuVoc description wasn't much more helpful, but the
examples after the description in Nuvoc cleared things up considerably.
Also, the dissect tool was very helpful in figuring out how J parsed the
whole dyadic verb. Who is the author of the dissect tool? That's a great
help in learning J.
Skip
Skip Cave
Cave Consulting LLC
On Sun, Sep 24, 2017 at 3:14 AM, Marshall Lochbaum <mwlochb...@gmail.com>
wrote:
> Try
>
> rng =: ] #~ 1=I.
>
> it's about half as fast because I. is not very well-optimized.
>
> Marshall
>
> On Sun, Sep 24, 2017 at 02:29:31AM -0500, Skip Cave wrote:
> > Here's a function I came up with to select numbers in a vector which are
> > within some range.
> >
> > Find all the numbers between 10 & 100 in a set of random numbers from 0
> to
> > 200:
> >
> >
> > rng =. 4 : '((({.x)</y)*.(({:x)>/y))#y'
> >
> >
> > 10 100 rng ?50$200
> >
> > 89 91 32 85 84 27 31 20 28 66 96 93 22 85 39 97 82 35 90 67 34 35 67 95
> 50
> >
> >
> > Between 120 & 180:
> >
> >
> > 120 180 rng ?50$200
> >
> > 148 163 133 165 150 178 121 146 161 179
> >
> >
> > Is there a more concise/efficient way to select numbers in a range?
> >
> > Skip Cave
> > Cave Consulting LLC
> > ----------------------------------------------------------------------
> > 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
