On Friday, 30 June 2023 at 16:14:48 UTC, jmh530 wrote:
On Thursday, 29 June 2023 at 23:51:44 UTC, bachmeier wrote:
[snip]
Glad you're continuing to do work on this front. There's a lot
of great material explaining things, which is always good.
It would be cool to have another version of the link below for
using a mir Slice with R.
https://bachmeil.github.io/betterr/setvar.html
I assume you mean that you've allocated memory on the D side,
like this:
```
auto a = new double[24];
a[] = 1.6;
Slice!(double*, 1) s = a.sliced();
```
and you want to pass s to R for further analysis. Unfortunately,
that will not work. R functions only work with memory R has
allocated. It has a single struct type, so there's no way to pass
s in this example to R.
The best you can do right now is something like this:
```
auto a = Vector(24);
Slice!(double*,1) s = a.ptr[0..24].sliced();
// Manipulate s
// Send a as an argument to R functions
```
In other words, you let R allocate a, and then you work with the
underlying data array as a slice.
A way around this limitation would be to implement the same
struct (SEXPREC) in D, while avoiding issues with R's garbage
collector. That's a more involved problem than I've been willing
to take on. If someone has the interest, the SEXPREC struct is
defined here:
https://github.com/wch/r-source/blob/060f8b64a3a8e489d8684c18b269eea63f182e73/src/include/Defn.h#L184 and the internals are documented here: https://cran.r-project.org/doc/manuals/r-release/R-ints.html#SEXPs
As much fun as it is to figure these things out, I have never had
sufficient time or motivation to do so.
