You need to regenerate rows and cols to match the matrix size you are
working with:
'row col'=. |:3 4 #:,i.3 4
pairs =: [: ,/ [: (2 ,/\ ])"1 (, |:)
pairs i. 3 3
0 1
1 2
3 4
4 5
6 7
7 8
0 3
3 6
1 4
4 7
2 5
5 8
FYI,
--
Raul
On Wed, Mar 6, 2013 at 3:24 PM, Zsbán Ambrus <[email protected]> wrote:
> On 2/24/13, km <[email protected]> wrote:
>> pairs =: [: ,/ [: (2 ,/\ ])"1 (, |:) NB. Constructs left-right and
>> up-down arcs
>> pairs i. 3 3 NB. left-right and up-down arcs
>
> This is a nice trick to create the list of edges. However, it doesn't
> work for a non-square matrix. For example, (pairs i. 3 4) will
> contain the edge (9 0) which shouldn't really be there.
>
>> CM=: #. e.~ [: i. [ , [ NB. Borrowed from 20. Directed Graphs in
>> Dictionary
>
> I find this method of converting the list to the adjacency matrix
> strange. I would instead use the amend verb, like this:
>
> CM =: (1:`(<"1@[)`]} 0$~,~)~
>
> Ambrus
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