Sadly, my version doesn't work. I suspect the convert_to_index verb
needs rework. Subsequently Pascal fixed it with
(#~ +/@(= [: <./ 0-.~,)@:([: | -/~)@:(j./"1))
Date: Thu, 17 Sep 2015 01:38:19 -0400
From: David Lambert<[email protected]>
To: programming<[email protected]>
Subject: Re: [Jprogramming] An adverb for a loopy algorithm
Message-ID:<[email protected]>
Content-Type: text/plain; charset=windows-1252; format=flowed
If your task is actually 2D, consider complex numbers. This version
performs better on the sample data P=:p
nearest_neighbors =: {~ convert_to_index@:identify_minimum@:separation
separation =: [: }. <@:|@:({: - }:)\&:(j./"1)
identify_minimum =: [: ; (i.L:0 <./@:;)
convert_to_index=:(0 1 + ] , i.) (#~ (<: i.@:#))
NB. examples by part
boxdraw_j_ 1
separation 4{.P
+-------+---------------+-----------------------+
|3.71611|6.01287 6.83522|1.30641 4.14391 7.31405|
+-------+---------------+-----------------------+
identify_minimum separation 4{.P
1 2 0
convert_to_index identify_minimum separation 4{.P
0 3
nearest_neighbors 4{.P
6.42201 5.83321
6.00479 7.07121
nearest_neighbors P
6.42201 5.83321
6.62593 6.08499
NB. time & space
close=: 3 :'y #~ +/@(= [: <./ 0-.~,)+/"1 *: -"1/~y' NB. RDM
flose=:nearest_neighbors f.
999 timespacex"0 1 'close P',:'flose P'
9.15946e_5 39680
5.26036e_5 10240
>Date: Wed, 16 Sep 2015 19:49:56 +0000 (UTC)
>From: "'Pascal Jasmin' via Programming"<[email protected]>
>To: Programming Forum<[email protected]>
>Subject: [Jprogramming] An adverb for a loopy algorithm
>Message-ID:
> <[email protected]>
>Content-Type: text/plain; charset=UTF-8
>
>finding the 2 closest points in a set, has a loopy algorithm of "for each point,
compare it with all of the points to its right"
>
>p =: 0 ". every cutLF 0 : 0
>6.42201 5.83321
>3.15448 4.06327
>8.89456 0.352235
>6.00479 7.07121
>8.10462 9.19487
>9.63448 4.00534
>6.74378 0.791349
>5.56034 9.27039
>4.67282 8.45993
>0.301042 9.4069
>6.62593 6.08499
>9.0307 2.37372
>9.36324 1.80147
>2.67396 1.62207
>4.76667 1.94554
>7.43839 6.05369
>)
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