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Dtype kind vs char #2864

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Merged
YannickJadoul merged 8 commits into from
Feb 23, 2021
Merged

Dtype kind vs char #2864

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df1be99
[dtype]: add type() method to access type attribute of PyArray_Descr …
Feb 15, 2021
b59299d
[dtype] change type() name method to char_() to be compliant with Pyt…
Feb 15, 2021
1400520
[dtype] fix by pre-commit
Feb 17, 2021
f455222
[dtype] Change comments and solutions format for test
Feb 17, 2021
400ffea
Clarify documentation and move note about dtype.char vs PyArray_Descr…
YannickJadoul Feb 17, 2021
f3ba900
Fix and extend tests
YannickJadoul Feb 17, 2021
14c9f7d
Fix the supposedly fixed tests
YannickJadoul Feb 17, 2021
46701ec
Fix the fixed tests again
YannickJadoul Feb 17, 2021
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12 changes: 11 additions & 1 deletion include/pybind11/numpy.h
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Original file line numberDiff line numberDiff line change
Expand Up@@ -507,11 +507,21 @@ class dtype : public object {
return detail::array_descriptor_proxy(m_ptr)->names != nullptr;
}

/// Single-character type code.
/// Single-character code for dtype's kind.
/// For example, floating point types are 'f' and integral types are 'i'.
char kind() const {
return detail::array_descriptor_proxy(m_ptr)->kind;
}

/// Single-character for dtype's type.
/// For example, ``float`` is 'f', ``double`` 'd', ``int`` 'i', and ``long`` 'd'.
char char_() const {
// Note: The signature, `dtype::char_` follows the naming of NumPy's
// public Python API (i.e., ``dtype.char``), rather than its internal
// C API (``PyArray_Descr::type``).
return detail::array_descriptor_proxy(m_ptr)->type;

@YannickJadoulYannickJadoulFeb 17, 2021

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Is it worth adding a comment that we're following the Python API of dtype (i.e., dtype.char), rather than NumPy's internal C API (PyArray_Descr::type), for the name?

See also https://numpy.org/devdocs/reference/c-api/types-and-structures.html#c.PyArray_Descr for the root cause of the type vs. char confusion.

@bemichelbemichelFeb 17, 2021

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okay !

}

private:
static object _dtype_from_pep3118() {
static PyObject *obj = module_::import("numpy.core._internal")
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20 changes: 20 additions & 0 deletions tests/test_numpy_dtypes.cpp
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Expand Up@@ -358,6 +358,14 @@ TEST_SUBMODULE(numpy_dtypes, m) {
});

// test_dtype
std::vector<const char *> dtype_names{
"byte", "short", "intc", "int_", "longlong",
"ubyte", "ushort", "uintc", "uint", "ulonglong",
"half", "single", "double", "longdouble",
"csingle", "cdouble", "clongdouble",
"bool_", "datetime64", "timedelta64", "object_"
};

m.def("print_dtypes", []() {
py::list l;
for (const py::handle &d : {
Expand All@@ -376,6 +384,18 @@ TEST_SUBMODULE(numpy_dtypes, m) {
return l;
});
m.def("test_dtype_ctors", &test_dtype_ctors);
m.def("test_dtype_kind", [dtype_names]() {
py::list list;
for (auto& dt_name : dtype_names)
list.append(py::dtype(dt_name).kind());
return list;
});
m.def("test_dtype_char_", [dtype_names]() {
py::list list;
for (auto& dt_name : dtype_names)
list.append(py::dtype(dt_name).char_());
return list;
});
m.def("test_dtype_methods", []() {
py::list list;
auto dt1 = py::dtype::of<int32_t>();
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3 changes: 3 additions & 0 deletions tests/test_numpy_dtypes.py
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Expand Up@@ -169,6 +169,9 @@ def test_dtype(simple_dtype):
np.zeros(1, m.trailing_padding_dtype())
)

assert m.test_dtype_kind() == list("iiiiiuuuuuffffcccbMmO")
assert m.test_dtype_char_() == list("bhilqBHILQefdgFDG?MmO")


def test_recarray(simple_dtype, packed_dtype):
elements = [(False, 0, 0.0, -0.0), (True, 1, 1.5, -2.5), (False, 2, 3.0, -5.0)]
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