Re: [xsl] Modeling matrices in an XML environment

["David Birnbaum djbpitt@xxxxxxxxx" <xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx>]

Thanks, Liam. This is very helpful. I had used schema-aware processing,
*@as*, and *@type* attributes when I tried the *<cell row="x" col="y">*
approach in the hope of avoiding unwanted type instability. But even when
that works, I hadn't thought about the overhead of the invisible unwanted
properties, and neither had I thought of using maps, which are, I now
realize, a lighter-weight alternative to the *<cell>* elements, with the
same advantages.

On Mon, Jul 13, 2020 at 5:58 PM Liam R. E. Quin liam@xxxxxxxxxxxxxxxx <
xsl-list-service@xxxxxxxxxxxxxxxxxxxxxx> wrote:

> On Mon, 2020-07-13 at 17:26 +0000, David Birnbaum djbpitt@xxxxxxxxx
> wrote:
> > Dear XSL-list,
> >
> > Roger's question invites a tangential one (for which reason I have
> > changed
> > the subject line): How might we usefully think about representing
> > matrices
> > in an XML environment?
>
> bit dependsbbfor performance in XPath/XQuery/XSLT/Xcetera ibd
probably
> use arrays or, for sparse matrices, maps. This is because the
> individual elements in mathematical matrices do not have intrinsic
> significance beyond the positional.
>
> For situations in which the elements _do_ have significant, there are
> obvious (to this crows) benefits to using XML names, or maps with named
> components,
>    "x" : 4.2, "y" : 7.2, "z" : 9
>
>
> The benefit to using maps or arrays over elements in XSLT or XQuery is
> that element nodes are too heavyweight, and too prone to turning their
> content back into strings. In XQuery in particular, constructors by
> default do a terrible and dismal thing: <x>3</x> makes a text node
> inside an x element. And XDM element nodes have a ton of properties,
> such as next, previous, parent, schema type, is_happy, none  of which
> are needed for a matrix of numbers.
>
> This is entirely separate from the MathML apprach, of course, whether
> content or presentational.
>
> For performance i'd consider also a single flat array,
>   [ r0c0 r0c1 .... r1c0.... ]
> with accessor functions my:mget($matrix, $row, $col) or whatever.
>
> It depends on the sort of manipulations you do.
>
> Liam
>
> --
> Liam Quin, https://www.delightfulcomputing.com/
> Available for XML/Document/Information Architecture/XSLT/
> XSL/XQuery/Web/Text Processing/A11Y training, work & consulting.
> Barefoot Web-slave, antique illustrations:  http://www.fromoldbooks.org