Ok. You have convinced me to go with the empty box as a null indicator. In
that case, we can make the Idot verb dyadic, and generalize it:
Idot =.[:I.&.>[:{="1
l1 =. 1 2 3 4 6 4 3 4 4 6 7 6
5 Idot l1
┌┐
││
└┘
l2 =. 5 2 3 4 6 4 3 5 4 6 7 6
5 Idot l2
┌───┐
│0 7│
└───┘
]m=.|:1 2 3 4,. 2 5 5 5,. 5 4 3 2 ,. 2 3 5 4,. 2 5 4 5
1 2 3 4
2 5 5 5
5 4 3 2
2 3 5 4
2 5 4 5
5 Idot m
┌┬─────┬─┬─┬───┐
││1 2 3│0│2│1 3│
└┴─────┴─┴─┴───┘
]n=.|:2 5 5 5,. 1 2 3 4,. 5 4 3 2 ,. 2 3 5 4,. 2 5 4 5
2 5 5 5
1 2 3 4
5 4 3 2
2 3 5 4
2 5 4 5
>m;n
2 5 5 5
1 2 3 4
5 4 3 2
2 3 5 4
2 5 4 5
1 2 3 4
2 5 5 5
5 4 3 2
2 3 5 4
2 5 4 5
5 Idot > m;n
┌─────┬─────┬─┬─┬───┐
│1 2 3│ │0│2│1 3│
├─────┼─────┼─┼─┼───┤
│ │1 2 3│0│2│1 3│
└─────┴─────┴─┴─┴───┘
NB. It's interesting what the monadic use of Idot does:
Idot l1
┌─┬─┬───┬───────┬──────┬──┐
│0│1│2 6│3 5 7 8│4 9 11│10│
└─┴─┴───┴───────┴──────┴──┘
Idot l2
┌───┬─┬───┬─────┬──────┬──┐
│0 7│1│2 6│3 5 8│4 9 11│10│
└───┴─┴───┴─────┴──────┴──┘
Idot m ┌─┬─────┬─┬─┐ │0│1 │2│3│ ├─┼─────┼─┼─┤ │0│1 2 3│ │ │ ├─┼─────┼─┼─┤
│0│1 │2│3│ ├─┼─────┼─┼─┤ │0│1 │2│3│ ├─┼─────┼─┼─┤ │0│1 3 │2│ │ └─┴─────┴─┴─┘
Idot n
┌─┬─────┬─┬─┐
│0│1 2 3│ │ │
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 3 │2│ │
└─┴─────┴─┴─┘
Idot >m;n
┌─┬─────┬─┬─┐
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 2 3│ │ │
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 3 │2│ │
└─┴─────┴─┴─┘
┌─┬─────┬─┬─┐
│0│1 2 3│ │ │
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 │2│3│
├─┼─────┼─┼─┤
│0│1 3 │2│ │
└─┴─────┴─┴─┘
Can you explain what's going on here?
Skip Cave
Cave Consulting LLC
On Sun, Jan 13, 2019 at 8:02 PM Ric Sherlock <[email protected]> wrote:
> Depending on what you are trying to acheive, I think I'd represent the lack
> of a match in a row as an empty rather than a _1:
>
> <@I."1 ] 5=m
>
> ┌┬─┬─┬─┐
>
> ││3│0│2│
>
> └┴─┴─┴─┘
>
>
> Of course if you need the _1 then you can transform the above
>
> ;@([: (a:=])`((<_1),:~ ])} <@I."1) 5 = m
>
>
> On Mon, Jan 14, 2019 at 10:42 AM 'Skip Cave' via Programming <
> [email protected]> wrote:
>
> > What I would really like is for I. to return a _1 whenever there is no 1
> in
> > the match array, since there cannot be a negative index:
> >
> > I.5=1 2 3 4 6 4 3 4 4 6 7 6
> >
> > 4 8 10
> >
> > Idot 5=1 2 3 4 6 4 3 4 4 6 7 6
> >
> > _1
> >
> >
> > ]m=.|:1 2 3 4,. 2 3 4 5,. 5 4 3 2 ,. 2 3 5 4
> >
> > 1 2 3 4
> >
> > 2 3 4 5
> >
> > 5 4 3 2
> >
> > 2 3 5 4
> >
> > 5=m
> >
> > 0 0 0 0
> >
> > 0 0 0 1
> >
> > 1 0 0 0
> >
> > 0 0 1 0
> >
> > ,Idot .5=m
> >
> > _1 3 0 2
> >
> >
> > Can a verb Idot be designed, that does this?
> >
> > Skip Cave
> > Cave Consulting LLC
> >
> >
> > On Sun, Jan 13, 2019 at 2:41 PM Henry Rich <[email protected]> wrote:
> >
> > > Right. Prefer (I.@:= ,) to I.@,@:= since it uses special code.
> > >
> > > Henry Rich
> > >
> > > On 1/13/2019 2:54 PM, 'Mike Day' via Programming wrote:
> > > > You often see this sort of thing, returning pairs of indices of all
> > > occurrences:
> > > >
> > > > 5 ($@] #.inv I.@,@:=) |: 1 2 3 4,. 2 3 4 5,. 5 4 3 2 ,. 2 3 5 4
> > > > 1 3
> > > > 2 0
> > > > 3 2
> > > >
> > > > You can obviously get the row indices using {:”1 or some such, and
> you
> > > can of course make the bracketed code a named dyadic verb,
> > > >
> > > > Cheers,
> > > >
> > > > Mike
> > > >
> > > >
> > > > Sent from my iPad
> > > >
> > > >> On 13 Jan 2019, at 17:55, 'Skip Cave' via Programming <
> > > [email protected]> wrote:
> > > >>
> > > >> I know I can find the location (index) of a specific integer in a
> > > vector of
> > > >> integers using I.
> > > >>
> > > >> I.5=1 2 3 4 5 4 3 4 5 6 5 6
> > > >>
> > > >> 4 8 10
> > > >>
> > > >>
> > > >> So I want to find the row index of a specific integer in an array of
> > > >> integers:
> > > >>
> > > >> |:1 2 3 4,. 2 3 4 5,. 5 4 3 2 ,. 2 3 5 4
> > > >>
> > > >> 1 2 3 4
> > > >>
> > > >> 2 3 4 5
> > > >>
> > > >> 5 4 3 2
> > > >>
> > > >> 2 3 5 4
> > > >>
> > > >> 5=|:1 2 3 4,. 2 3 4 5,. 5 4 3 2 ,. 2 3 5 4
> > > >>
> > > >> 0 0 0 0
> > > >>
> > > >> 0 0 0 1
> > > >>
> > > >> 1 0 0 0
> > > >>
> > > >> 0 0 1 0
> > > >>
> > > >> ,I. 5=|:1 2 3 4,. 2 3 4 5,. 5 4 3 2 ,. 2 3 5 4
> > > >>
> > > >> 0 3 0 2
> > > >>
> > > >>
> > > >> The first zero indicates that there is no 5 in the first row. The
> > second
> > > >> zero gives the index of the 5 in the third row. How can I tell
> whether
> > > the
> > > >> zero is an index, or a null indicator?
> > > >>
> > > >> Skip
> > > >>
> ----------------------------------------------------------------------
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