If you find the inv-thing quirky and complex numbers too, you can use e.g. 1 2
1#M to duplicate a row of M. Then put something else at the copy using }
(amend), but you were probably going to do that anyhow.
I use a verb called ins that behaves like } , except that it inserts :)
888 (3) ins i.10
0 1 2 888 3 4 5 6 7 8 9
2 (2) ins "1 (1) (2) ins (3 3$0)
0 0 2 0
0 0 2 0
1 1 2 1
0 0 2 0
77 (2 5) ins i.10
0 1 77 2 3 4 77 5 6 7 8 9
I'm sure some of you can do it nicer, but my ins looks like:
ins
1 : (':'; 'x ((+i.@#)m)}(>:(i.#y)e.m)#y')
The (+i.@#)m piece, instead of just m, is intended to allow for inserting
multiple items, like in the last example.
Ben
________________________________________
From: [email protected]
[[email protected]] on behalf of Sebastian
[[email protected]]
Sent: Thursday, September 11, 2014 13:04
To: [email protected]
Subject: Re: [Jprogramming] Extend/reduce matrix dimensions
Hi Raul and Dan,
Many thanks for your great help! :)
I found # as copy in the j vocabulary now, but I cannot find #inv. Where
I have to search?
Sebastian
------ Originalnachricht ------
Von: "Raul Miller" <[email protected]>
An: "Programming forum" <[email protected]>
Gesendet: 11.09.2014 12:58:37
Betreff: Re: [Jprogramming] Extend/reduce matrix dimensions
>Here's an example of how I frequently use non-truth-valued #
>
> 9!:7]9 1 1#'+|-'
>
>Thanks,
>
>--
>Raul
>
>On Thu, Sep 11, 2014 at 6:49 AM, Dan Bron <[email protected]> wrote:
>
>> Note also that you can use plain, uninverted # to expand arguments:
>>
>> 1 1j1 1 (#!.1) 3 3 $ 0
>> 0 0 0
>> 0 0 0
>> 1 1 1
>> 0 0 0
>> 1 1j1 1 (#!.1"1) 3 3 $ 0
>> 0 0 1 0
>> 0 0 1 0
>> 0 0 1 0
>>
>>
>> Which approach you pick often depends on whether it's easier for you
>>to
>> express your expansion vector with length N (complex numbers) or N+1
>> (boolean numbers).
>>
>> -Dan
>>
>> This is worth remembering as well, though I rarely see it used:
>>
>> 1 2 1 # i. 3 3
>> 0 1 2
>> 3 4 5
>> 3 4 5
>> 6 7 8
>>
>> Please excuse typos; sent from a phone.
>>
>> > On Sep 11, 2014, at 5:32 AM, Raul Miller <[email protected]>
>>wrote:
>> >
>> > Here are some perhaps relevant examples:
>> >
>> > 1 1 0 1 #inv (3 3$ 0)
>> > 0 0 0
>> > 0 0 0
>> > 0 0 0
>> > 0 0 0
>> > 1 1 0 1 #inv!.1 (3 3$ 0)
>> > 0 0 0
>> > 0 0 0
>> > 1 1 1
>> > 0 0 0
>> > 1 1 0 1 #inv!.1"1 (3 3$ 0)
>> > 0 0 1 0
>> > 0 0 1 0
>> > 0 0 1 0
>> > 1 1 0 1 #inv!.1"1 (1 1 0 1) #inv!.1 (3 3$ 0)
>> > 0 0 1 0
>> > 0 0 1 0
>> > 1 1 1 1
>> > 0 0 1 0
>> > 1 1 0 1 # 1 1 0 1 #inv!.1"1 (1 1 0 1) #inv!.1 (3 3$ 0)
>> > 0 0 1 0
>> > 0 0 1 0
>> > 0 0 1 0
>> > 1 1 0 1 #("1) 1 1 0 1 # 1 1 0 1 #inv!.1"1 (1 1 0 1) #inv!.1 (3 3$
>>0)
>> > 0 0 0
>> > 0 0 0
>> > 0 0 0
>> > (i.3) 2} 1 1 0 1 #inv (3 3$0)
>> > 0 0 0
>> > 0 0 0
>> > 0 1 2
>> > 0 0 0
>> > (i.4) 2}"0 1 (1 1 0 1) #inv"1 (i.3) 2} 1 1 0 1 #inv (3 3$0)
>> > 0 0 0 0
>> > 0 0 1 0
>> > 0 1 2 2
>> > 0 0 3 0
>> > (i.4) 2}"0 1 (1 1 0 1) #inv"1 (0 1 3) 2} 1 1 0 1 #inv (3 3$0)
>> > 0 0 0 0
>> > 0 0 1 0
>> > 0 1 2 3
>> > 0 0 3 0
>> >
>> > The whole #inv thing is a bit quirky but was quite deliberate. This
>>was a
>> > primitive in APL, but the syntax was ... strange. Rather than
>>trying to
>> > find a special symbol for this operation, Iverson put it on #inv
>>(since -
>> > logically speaking - it's the inverse of #).
>> >
>> > Thanks,
>> >
>> > --
>> > Raul
>> >
>> >
>> >> On Thu, Sep 11, 2014 at 5:21 AM, Sebastian <[email protected]>
>>wrote:
>> >>
>> >> Hi,
>> >>
>> >> I know the verbs , ,. ,: to add rows, columns and dimensions to
>> matrices.
>> >> It is easy to add these to begin or the end of the corrosponding
>> dimension,
>> >> but what is to do, if I want to add one row/column in the middle
>>of a
>> >> matrix? Is the only way to slice the matrix in two pieces and join
>>them
>> >> with the new row/column?
>> >>
>> >> A few examples:
>> >>
>> >> Initial situation:
>> >>
>> >> 3 3 $ 0
>> >> 0 0 0
>> >>
>> >> 0 0 0
>> >>
>> >> 0 0 0
>> >>
>> >>
>> >> add column somewhere to the middle:
>> >>
>> >> 0 0 1 0
>> >>
>> >> 0 0 1 0
>> >>
>> >> 0 0 1 0
>> >>
>> >>
>> >>
>> >> add row somewhere to the middle:
>> >>
>> >> 0 0 1 0
>> >>
>> >> 0 0 1 0
>> >>
>> >> 1 1 1 1
>> >>
>> >> 0 0 1 0
>> >>
>> >>
>> >> remove the added column:
>> >>
>> >> 0 0 0
>> >>
>> >> 0 0 0
>> >>
>> >> 1 1 1
>> >>
>> >> 0 0 0
>> >>
>> >>
>> >>
>> >> and the row:
>> >>
>> >>
>> >>
>> >> 0 0 0
>> >>
>> >> 0 0 0
>> >>
>> >> 0 0 0
>> >>
>> >>
>> >>
>> >> Can anyone help me with this?
>> >>
>> >>
>> >>
>> >> Regards
>> >>
>> >> Sebastian
>> >>
>>----------------------------------------------------------------------
>> >> 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
>>
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