[Jprogramming] indirect assignment and rank question

[Linda Alvord]

Why is it necessary to include  &  in each of these example?

   (0 1&|:A)-:0 1|:A=:?3 2 4$5 
1
   (2 0 1|:A)-:0 1|:A
1
   (0 1 2|:B)-:3 0 1 2|:B=:?3 2 5 4$5 
1
  
   (0 1 2&|:B)-:3 0 1 2&|:B=:?3 2 5 4$5 
1


Linda

-----Original Message-----
From: programming-bounces at forums.jsoftware.com
[mailto:programming-bounces at forums.jsoftware.com] On Behalf Of Dan Bron
Sent: Friday, December 07, 2012 6:05 PM
To: programming at jsoftware.com
Cc: programming at jsoftware.com
Subject: Re: [Jprogramming] indirect assignment and rank question

Something I never wrapped my head around with |: is what exactly the DoJ
means when it says axes are "run together" when the LHA is boxed.

-Dan


On Dec 7, 2012, at 3:28 PM, Marshall Lochbaum <mwlochbaum at gmail.com> wrote:

> 0 1 2&|: will do the job.
> 
> I recommend reading the dictionary definition of |: through a few times.
> In particular, note that 0 1&|: on a rank three array is the same as
> 2 0 1&|: , and 0 1 2&|: turns into 3 0 1 2&|: on a rank four array.
> 
> Marshall
> 
> On Fri, Dec 07, 2012 at 03:02:49PM -0500, Brian Schott wrote:
>> I am working with photographic images which use RGB color.
>> The array d is a single image and the array D is now 2 images but I 
>> want D to contain any number of images. And I want split out the R,G, 
>> and B part which I can do for d, but I am having difficulty with the 
>> analogous r, g, and b for D.
>> 
>>   $d
>> 50 50 3
>>   $D
>> 2 50 50 3
>> 
>>   'R G B'=: 0 1|: d
>>   $G
>> 50 50
>> 
>> What is the mysteryverb that will produce ($g)-:2 50 50 in the 
>> following expression?
>>   'r g b'=: mysteryverb D
>> 
>> Thanks,
>> 
>> (B=)
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