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Accept read-only NumPy arrays in Eigen vector constructors #7607

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Accept read-only NumPy arrays in Eigen vector constructors #7607

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28 changes: 16 additions & 12 deletions cpp/pybind/utility/eigen.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,12 +47,12 @@ std::vector<EigenVector> py_array_to_vectors_double(
throw py::cast_error();
}
std::vector<EigenVector> eigen_vectors(array.shape(0));
auto array_unchecked = array.mutable_unchecked<2>();
auto array_unchecked = array.unchecked<2>();
for (auto i = 0; i < array_unchecked.shape(0); ++i) {
// The EigenVector here must be a double-typed eigen vector, since only
// open3d::Vector3dVector binds to py_array_to_vectors_double.
// Therefore, we can use the memory map directly.
eigen_vectors[i] = Eigen::Map<EigenVector>(&array_unchecked(i, 0));
// Vector2dVector and Vector3dVector both use double-typed Eigen
// vectors. Copy through a const map to also accept read-only arrays.
eigen_vectors[i] =
Eigen::Map<const EigenVector>(&array_unchecked(i, 0));
}
return eigen_vectors;
}
Expand All @@ -67,9 +67,10 @@ std::vector<EigenVector> py_array_to_vectors_int(py::array_t<int> array) {
throw py::cast_error();
}
std::vector<EigenVector> eigen_vectors(array.shape(0));
auto array_unchecked = array.mutable_unchecked<2>();
auto array_unchecked = array.unchecked<2>();
for (auto i = 0; i < array_unchecked.shape(0); ++i) {
eigen_vectors[i] = Eigen::Map<EigenVector>(&array_unchecked(i, 0));
eigen_vectors[i] =
Eigen::Map<const EigenVector>(&array_unchecked(i, 0));
}
return eigen_vectors;
}
Expand All @@ -86,9 +87,10 @@ py_array_to_vectors_int_eigen_allocator(py::array_t<int> array) {
throw py::cast_error();
}
std::vector<EigenVector, EigenAllocator> eigen_vectors(array.shape(0));
auto array_unchecked = array.mutable_unchecked<2>();
auto array_unchecked = array.unchecked<2>();
for (auto i = 0; i < array_unchecked.shape(0); ++i) {
eigen_vectors[i] = Eigen::Map<EigenVector>(&array_unchecked(i, 0));
eigen_vectors[i] =
Eigen::Map<const EigenVector>(&array_unchecked(i, 0));
}
return eigen_vectors;
}
Expand All @@ -105,9 +107,10 @@ py_array_to_vectors_int64_eigen_allocator(py::array_t<int64_t> array) {
throw py::cast_error();
}
std::vector<EigenVector, EigenAllocator> eigen_vectors(array.shape(0));
auto array_unchecked = array.mutable_unchecked<2>();
auto array_unchecked = array.unchecked<2>();
for (auto i = 0; i < array_unchecked.shape(0); ++i) {
eigen_vectors[i] = Eigen::Map<EigenVector>(&array_unchecked(i, 0));
eigen_vectors[i] =
Eigen::Map<const EigenVector>(&array_unchecked(i, 0));
}
return eigen_vectors;
}
Expand Down Expand Up @@ -361,7 +364,8 @@ Example usage
pcd = open3d.geometry.PointCloud()
np_points = np.random.rand(100, 3)

# From numpy to Open3D
# From numpy to Open3D: the input is copied and may be read-only.
np_points.setflags(write=False)
pcd.points = open3d.utility.Vector3dVector(np_points)

# From Open3D to numpy
Expand Down
47 changes: 47 additions & 0 deletions python/test/test_open3d_eigen.py
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Expand Up @@ -156,6 +156,53 @@ def run_test(input_array):
run_test(input_array)


@pytest.mark.parametrize("vector_name, width, dtype", [
("Vector2dVector", 2, np.float64),
("Vector3dVector", 3, np.float64),
("Vector2iVector", 2, np.int32),
("Vector3iVector", 3, np.int32),
("Vector4iVector", 4, np.int32),
])
@pytest.mark.parametrize("writeable", [True, False],
ids=["writable", "readonly"])
@pytest.mark.parametrize(
"layout",
["c", "empty", "fortran", "column_slice", "reversed", "converted"])
def test_eigen_vector_numpy_input_is_copied(vector_name, width, dtype,
writeable, layout):
input_array = np.arange(4 * width, dtype=dtype).reshape(4, width)
if layout == "empty":
input_array = input_array[:0]
elif layout == "fortran":
input_array = np.asfortranarray(input_array)
elif layout == "column_slice":
input_array = np.arange(8 * width, dtype=dtype).reshape(4, 2 * width)
input_array = input_array[:, ::2]
elif layout == "reversed":
input_array = input_array[::-1, ::-1]
elif layout == "converted":
converted_dtype = np.float32 if dtype == np.float64 else np.int64
input_array = input_array.astype(converted_dtype)
input_array.setflags(write=writeable)
expected = input_array.copy()

vector = getattr(o3d.utility, vector_name)(input_array)
output_array = np.asarray(vector)

assert output_array.dtype == np.dtype(dtype)
np.testing.assert_array_equal(output_array, expected)
assert not np.shares_memory(output_array, input_array)
assert input_array.flags.writeable == writeable
np.testing.assert_array_equal(input_array, expected)

# Open3D owns the copy even when the NumPy input is read-only.
output_array[...] = -1
np.testing.assert_array_equal(np.asarray(vector),
np.full_like(expected, -1))
np.testing.assert_array_equal(input_array, expected)
assert input_array.flags.writeable == writeable


# Run with pytest -s to show output
def test_benchmark():
vector_size = int(2e6)
Expand Down
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