commit | 59a281cca2ed63925931f6fd0dc492a7dbbb4530 | [log] [tgz] |
---|---|---|
author | Dewey Dunnington <dewey@dunnington.ca> | Mon Apr 15 09:44:40 2024 -0300 |
committer | GitHub <noreply@github.com> | Mon Apr 15 09:44:40 2024 -0300 |
tree | a192a916bdf366c575d03f2b8dbae86c4a159919 | |
parent | 11e73a8c85b45e3d49c8c541b4e1497a649fe03c [diff] |
feat(python): Support Decimal types in convert to Python (#425) I experimented with a few different methods here...I think this one has a good balance of speed and not messing with the global precision. ```python import pyarrow as pa import decimal from nanoarrow.iterator import iter_py items = [decimal.Decimal("12.3450"), None, decimal.Decimal("1234567.3456")] array = pa.array(items, pa.decimal128(11, 4)) list(iter_py(array)) #> [Decimal('12.3450'), None, Decimal('1234567.3456')] ``` This seems to be vaguely on par with pyarrow convert: ```python import pyarrow as pa import decimal import numpy as np from nanoarrow.iterator import iter_py floats = np.random.random(int(1e6)) items = [decimal.Decimal(item) for item in floats] array = pa.array(items) %timeit array.to_pylist() #> 799 ms ± 6.24 ms per loop (mean ± std. dev. of 7 runs, 1 loop each) %timeit list(iter_py(array)) #> 431 ms ± 8.65 ms per loop (mean ± std. dev. of 7 runs, 1 loop each) ```
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/nanoarrow.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(ArrowSchemaInitFromType(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; }
CMake is the officially supported build system for nanoarrow. However, the Meson backend is an experimental feature you may also wish to try.
To run the test suite with Meson, you will want to first install the testing dependencies via the wrap database (n.b. no wrap database entry exists for Arrow - that must be installed separately).
mkdir subprojects meson wrap install gtest meson wrap install google-benchmark meson wrap install nlohmann_json
The Arrow C++ library must also be discoverable via pkg-config build tests.
You can then set up your build directory:
meson setup builddir
cd builddir
And configure your project (this could have also been done inline with setup
)
meson configure -DNANOARROW_BUILD_TESTS=true -DNANOARROW_BUILD_BENCHMARKS=true
Note that if your Arrow pkg-config profile is installed in a non-standard location on your system, you may pass the --pkg-config-path <path to directory with arrow.pc>
to either the setup or configure steps above.
With the above out of the way, the compile
command should take care of the rest:
meson compile
Upon a successful build you can execute the test suite and benchmarks with the following commands:
meson test nanoarrow: # default test run meson test nanoarrow: --wrap valgrind # run tests under valgrind meson test nanoarrow: --benchmark --verbose # run benchmarks