ndarray bind string array

[zingdle]

nb::ndarray can't bind to string array, including zero-terminated bytes or unicode string. Will this feature get considered? Thanks!

#include <nanobind/nanobind.h>
#include <nanobind/ndarray.h>
#include <nanobind/stl/vector.h>

namespace nb = nanobind;

NB_MODULE(myext, m) {
  m.def("foo", [](nb::ndarray<nb::numpy> a) {
    printf("itemsize: %ld\n", a.itemsize());
  });
}

>>> import numpy as np
>>> import myext
>>> a = np.array(['apples', 'foobar', 'cowboy'])
>>> a.dtype
dtype('<U6')
>>> b = np.array(['apples', 'foobar', 'cowboy'], dtype='S10')
>>> b.dtype
dtype('S10')
>>> c = np.array([1, 2, 3])
>>> c.dtype
dtype('int64')
>>> myext.foo(a)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: foo(): incompatible function arguments. The following argument types are supported:
    1. foo(arg: numpy.ndarray[], /) -> None

Invoked with types: ndarray
>>> myext.foo(b)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: foo(): incompatible function arguments. The following argument types are supported:
    1. foo(arg: numpy.ndarray[], /) -> None

Invoked with types: ndarray
>>> myext.foo(c)
itemsize: 8

[wjakob]

It's not supported and unlikely to be realized any time soon because nanobind's nd-array interface is based on DLPack (link: https://github.com/dmlc/dlpack). DLPack doesn't support strings; 8-bit ints is the closest approximation, but that doesn't consider things like unicode.