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-rw-r--r--ext/pybind11/docs/advanced/pycpp/numpy.rst26
1 files changed, 23 insertions, 3 deletions
diff --git a/ext/pybind11/docs/advanced/pycpp/numpy.rst b/ext/pybind11/docs/advanced/pycpp/numpy.rst
index 98b0c25b9..458f99e97 100644
--- a/ext/pybind11/docs/advanced/pycpp/numpy.rst
+++ b/ext/pybind11/docs/advanced/pycpp/numpy.rst
@@ -41,7 +41,7 @@ completely avoid copy operations with Python expressions like
py::format_descriptor<float>::format(), /* Python struct-style format descriptor */
2, /* Number of dimensions */
{ m.rows(), m.cols() }, /* Buffer dimensions */
- { sizeof(float) * m.rows(), /* Strides (in bytes) for each index */
+ { sizeof(float) * m.cols(), /* Strides (in bytes) for each index */
sizeof(float) }
);
});
@@ -261,7 +261,7 @@ simply using ``vectorize``).
namespace py = pybind11;
py::array_t<double> add_arrays(py::array_t<double> input1, py::array_t<double> input2) {
- auto buf1 = input1.request(), buf2 = input2.request();
+ py::buffer_info buf1 = input1.request(), buf2 = input2.request();
if (buf1.ndim != 1 || buf2.ndim != 1)
throw std::runtime_error("Number of dimensions must be one");
@@ -272,7 +272,7 @@ simply using ``vectorize``).
/* No pointer is passed, so NumPy will allocate the buffer */
auto result = py::array_t<double>(buf1.size);
- auto buf3 = result.request();
+ py::buffer_info buf3 = result.request();
double *ptr1 = (double *) buf1.ptr,
*ptr2 = (double *) buf2.ptr,
@@ -364,3 +364,23 @@ uses of ``py::array``:
The file :file:`tests/test_numpy_array.cpp` contains additional examples
demonstrating the use of this feature.
+
+Ellipsis
+========
+
+Python 3 provides a convenient ``...`` ellipsis notation that is often used to
+slice multidimensional arrays. For instance, the following snippet extracts the
+middle dimensions of a tensor with the first and last index set to zero.
+
+.. code-block:: python
+
+ a = # a NumPy array
+ b = a[0, ..., 0]
+
+The function ``py::ellipsis()`` function can be used to perform the same
+operation on the C++ side:
+
+.. code-block:: cpp
+
+ py::array a = /* A NumPy array */;
+ py::array b = a[py::make_tuple(0, py::ellipsis(), 0)];