eddelbuettel commented on issue #67:
URL: https://github.com/apache/arrow-nanoarrow/issues/67#issuecomment-1337421412
Hi @paleolimbot -- the list in #71 looks great, and the recent PR also
containing streams are very useful too. Sadly there is still too much
different in `nanoarrow` relative to your various predecessor projects (with
still work) for me to make a switch. I took the above and extended it
minimally. I get what looks like a reasonable Arrow object but trying to
materialize it into a `tibble` blows up (whereas this works just fine as it
should with the predecessors):
```sh
> rl <- rcppnanoarrow::createArray()
> unclass(rl)
$schema
<pointer: 0x55e569b9d0f0>
attr(,"class")
[1] "arch_schema"
$array_data
<pointer: 0x55e5690ec1a0>
attr(,"class")
[1] "arch_array_data"
> arrow::as_arrow_table(arch::from_arch_array(rl, arrow::RecordBatch))
Table
3 rows x 2 columns
$intCol <int32>
$dblCol <double>
> tibble::as_tibble(arrow::as_arrow_table(arch::from_arch_array(rl,
arrow::RecordBatch)))
*** caught segfault ***
address (nil), cause 'memory not mapped'
Traceback:
1: vec_slice(x, seq_len(n))
2: vec_head(as.data.frame(x), n)
3: df_head(x, n)
4: tbl_format_setup.tbl(x, width, ..., n = n, max_extra_cols =
max_extra_cols, max_footer_lines = max_footer_lines, focus = focus)
5: tbl_format_setup_dispatch(x, width, ..., n = n, max_extra_cols =
max_extra_cols, max_footer_lines = max_footer_lines, focus = focus)
6: tbl_format_setup(x, width = width, ..., n = n, max_extra_cols =
max_extra_cols, max_footer_lines = max_footer_lines, focus = attr(x,
"pillar_focus"))
7: format_tbl(x, width, ..., n = n, max_extra_cols = max_extra_cols,
max_footer_lines = max_footer_lines)
8: format.tbl(x, width = width, ..., n = n, max_extra_cols =
max_extra_cols, max_footer_lines = max_footer_lines)
9: format(x, width = width, ..., n = n, max_extra_cols = max_extra_cols,
max_footer_lines = max_footer_lines)
10: writeLines(format(x, width = width, ..., n = n, max_extra_cols =
max_extra_cols, max_footer_lines = max_footer_lines))
11: print_tbl(x, width, ..., n = n, max_extra_cols = max_extra_cols,
max_footer_lines = max_footer_lines)
12: print.tbl(x)
13: (function (x, ...) UseMethod("print"))(x)
Possible actions:
1: abort (with core dump, if enabled)
2: normal R exit
3: exit R without saving workspace
4: exit R saving workspace
Selection:
```
The simple helper function to create the object is below, it is a simple
extension of the example stub you posted. Can you spot what I am missing here?
(And I tried to different s3 classes for dispatch.)
<details>
Simple Rcpp-wrapped object creator below. It uses a list for convenience to
transport the two external pointers to schema and array data, following prior
practice in narrow/sparrow/carrow/...
```c++
//' @export
// [[Rcpp::export]]
Rcpp::List createArray() {
const int ncol = 2;
const int nrow = 3;
auto schemaxp = Rcpp::XPtr<struct ArrowSchema>(new struct ArrowSchema);
schemaxp.attr("class") = "arch_schema";
auto schema = schemaxp.get();
ArrowSchemaInit(schema, NANOARROW_TYPE_STRUCT);
ArrowSchemaAllocateChildren(schema, ncol);
auto arrayxp = Rcpp::XPtr<struct ArrowArray>(new struct ArrowArray);
arrayxp.attr("class") = "arch_array_data";
auto array = arrayxp.get();
ArrowArrayInit(array, NANOARROW_TYPE_STRUCT);
ArrowArrayAllocateChildren(array, ncol);
array->length = nrow;
array->null_count = -1;
// ...fill in schema.children and array.children
ArrowSchemaInit(schema->children[0], NANOARROW_TYPE_INT32);
ArrowSchemaSetName(schema->children[0], "intCol");
ArrowArrayInit(array->children[0], NANOARROW_TYPE_INT32);
ArrowArrayAppendInt(array->children[0], 21);
ArrowArrayAppendInt(array->children[0], 42);
ArrowArrayAppendInt(array->children[0], 63);
ArrowSchemaInit(schema->children[1], NANOARROW_TYPE_DOUBLE);
ArrowSchemaSetName(schema->children[1], "dblCol");
ArrowArrayInit(array->children[1], NANOARROW_TYPE_DOUBLE);
ArrowArrayAppendDouble(array->children[1], 21.1);
ArrowArrayAppendDouble(array->children[1], 42.2);
ArrowArrayAppendDouble(array->children[1], 63.3);
Rcpp::List as = Rcpp::List::create(Rcpp::Named("schema") = schemaxp,
Rcpp::Named("array_data") = arrayxp);
//as.attr("class") = "nanoarrow_array";
as.attr("class") = "arch_array";
return as;
}
```
</details>
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