commit | 1e6ca7e2080ba0cab54ee6a23fd42df4dfb76e30 | [log] [tgz] |
---|---|---|
author | Dewey Dunnington <dewey@dunnington.ca> | Tue May 30 08:49:38 2023 -0400 |
committer | GitHub <noreply@github.com> | Tue May 30 09:49:38 2023 -0300 |
tree | 3214bca3ea908e01ad7ce85078f8aa1506f3a187 | |
parent | dcb33f09f4c91ca3f1f288365d37fbb6301efb26 [diff] |
feat: Add `enum ArrowType buffer_data_type` member to `struct ArrowLayout` (#207) The existing `enum ArrowBufferType` is useful to switch on for some things and the `element_size_bits` is useful for calculating byte offsets; however, the combination of those is still not sufficient to do endian-swapping as each Arrow type has its own rules. This concept has also come up when printing buffers in the R package and when exporting in Python via the buffer protocol, both of which had their own workarounds. Attaching a reasonable `ArrowType` to each buffer should provide a generic route to solving all of those.
The nanoarrow library is a set of helper functions to interpret and generate Arrow C Data Interface and Arrow C Stream Interface structures. The library is in active early development and users should update regularly from the main branch of this repository.
Whereas the current suite of Arrow implementations provide the basis for a comprehensive data analysis toolkit, this library is intended to support clients that wish to produce or interpret Arrow C Data and/or Arrow C Stream structures where linking to a higher level Arrow binding is difficult or impossible.
The nanoarrow C library is intended to be copied and vendored. This can be done using CMake or by using the bundled nanoarrow.h/nanorrow.c distribution available in the dist/ directory in this repository. Examples of both can be found in the examples/ directory in this repository.
A simple producer example:
#include "nanoarrow.h" int make_simple_array(struct ArrowArray* array_out, struct ArrowSchema* schema_out) { struct ArrowError error; array_out->release = NULL; schema_out->release = NULL; NANOARROW_RETURN_NOT_OK(ArrowArrayInitFromType(array_out, NANOARROW_TYPE_INT32)); NANOARROW_RETURN_NOT_OK(ArrowArrayStartAppending(array_out)); NANOARROW_RETURN_NOT_OK(ArrowArrayAppendInt(array_out, 1)); NANOARROW_RETURN_NOT_OK(ArrowArrayAppendInt(array_out, 2)); NANOARROW_RETURN_NOT_OK(ArrowArrayAppendInt(array_out, 3)); NANOARROW_RETURN_NOT_OK(ArrowArrayFinishBuildingDefault(array_out, &error)); NANOARROW_RETURN_NOT_OK(ArrowSchemaInit(schema_out, NANOARROW_TYPE_INT32)); return NANOARROW_OK; }
A simple consumer example:
#include <stdio.h> #include "nanoarrow.h" int print_simple_array(struct ArrowArray* array, struct ArrowSchema* schema) { struct ArrowError error; struct ArrowArrayView array_view; NANOARROW_RETURN_NOT_OK(ArrowArrayViewInitFromSchema(&array_view, schema, &error)); if (array_view.storage_type != NANOARROW_TYPE_INT32) { printf("Array has storage that is not int32\n"); } int result = ArrowArrayViewSetArray(&array_view, array, &error); if (result != NANOARROW_OK) { ArrowArrayViewReset(&array_view); return result; } for (int64_t i = 0; i < array->length; i++) { printf("%d\n", (int)ArrowArrayViewGetIntUnsafe(&array_view, i)); } ArrowArrayViewReset(&array_view); return NANOARROW_OK; }