Thanks. I have to say, with no reflection on present company, I am about
as frustrated and disgusted with nested arrays, as defined by IBM, as I
could be. Having enclose do one thing for all arrays and another for
scalars has caused me endless hours of frustration. (Isn't a scalar just a
zero dimension array?) How much time has one to spend making enclose do
what comes naturally to ones mind? Now I find that disclose actually
modifies data beyond the ability to reconstruct it. In your example, if
one string were a different length than the other, APL will lengthen it to
match the longest upon disclose. The original length of each string is
lost forever. Why stop there? Why not change a 4 to a 7?
Having enclose and disclose uniformly add and remove layers of boxing only
is simple, consistent, predictable, useful, and easy to understand. If I
add 3 and then subtract 3 I end up with the same number. But if I enclose
and then disclose, I end up with something different - sometimes. Imagine
that!
'333' '55555'
┌→────────────┐
│┌→──┐ ┌→────┐│
││333│ │55555││
│└───┘ └─────┘│
└∊────────────┘
⊃'333' '55555'
┌→────┐
↓333 │
│55555│
└─────┘
(⊃'333' '55555')[1;]
┌→────┐
│333 │
└─────┘
⍴(⊃'333' '55555')[1;]
┌→┐
│5│
└─┘
There are ways to rationalize almost anything. IMO, the IBM nested array
approach is confusing, unpredictable, and renders it a tool of very careful
last resort.
I know there has been debate about this in the past, and I am not looking
to resurrect it. It is a real shame IBM chose the path it chose.
Blake
On Mon, May 12, 2014 at 5:08 AM, Jay Foad <[email protected]> wrote:
> APL2's Disclose (Dyalog calls it Mix) will convert a vector of vectors
> into a matrix:
>
> ⊃'timor' 'mortis'
> ┌→─────┐
> ↓timor │
> │mortis│
> └──────┘
>
> Your second application of Disclose is applied to a 1-vector of
> 1-vectors (,⊂,7), so it returns a 1x1 matrix.
>
> Jay.
>
> On 12 May 2014 06:03, Blake McBride <[email protected]> wrote:
> > ⊃⊃⊂,⊂,7
> > ┌→┐
> > ↓7│
> > └─┘
> > ⍴⊃⊃⊂,⊂,7
> > ┌→──┐
> > │1 1│
> > └───┘
> >
>
