Fix Numpy API example and add one for Pybind11

Author: XuhuaHuang

NumPyAPI/CMakeLists.txt

@@ -1,13 +1,13 @@
-cmake_minimum_required(VERSION 3.18)
+cmake_minimum_required(VERSION 3.20)
 
-project("numpy_cxx")
+project("numpy_cxx" LANGUAGES CXX)
 
-set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
 
-add_executable(numpycxx main.cpp)
+find_package(Python3 COMPONENTS Interpreter NumPy Development REQUIRED)
 
-find_package (Python3 COMPONENTS Interpreter NumPy Development REQUIRED)
+add_executable(numpycxx main.cpp)
 
 # Stop Visual Studio Solution from looking for python311_d.dll
 set(CMAKE_BUILD_TYPE Release)
@@ -23,5 +23,6 @@ target_include_directories(numpycxx
 target_link_libraries(numpycxx
     PUBLIC
     ${PYTHON_LIBRARIES}
+    Python3::Python
     Python3::NumPy
 )

NumPyAPI/main.cpp

@@ -1,57 +1,58 @@
+// clang-format off
 /*****************************************************************//**
  * \file   main.cpp
  * \brief  
  * 
  * \author Xuhua Huang
  * \date   January 07, 2023
  *********************************************************************/
+// clang-format on
 
 #define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
 
 #include <Python.h>
 #include <numpy/arrayobject.h>
 
 #include <cstdlib>
-#include <iostream>
 
 auto main(int argc, char* argv[]) -> int {
-    // Initialize the Python interpreter
-    Py_Initialize();
-
-    // Import the NumPy module
-    PyObject* numpy = PyImport_ImportModule("numpy");
-
-    // Convert a Python list to a NumPy array
-    PyObject* list = PyList_New(3);
-    PyList_SetItem(list, 0, PyLong_FromLong(1));
-    PyList_SetItem(list, 1, PyLong_FromLong(2));
-    PyList_SetItem(list, 2, PyLong_FromLong(3));
-    PyObject* array = PyObject_CallMethod(numpy, "array", "O", list);
-
-    // Get the data type of the array
-    PyObject*   dtype = PyObject_GetAttrString(array, "dtype");
-    const char* str   = PyUnicode_AsUTF8(dtype);
-    printf("Data type: %s\n", str);
-
-    // Get the shape of the array
-    PyObject*  shape = PyObject_GetAttrString(array, "shape");
-    Py_ssize_t len   = PyTuple_Size(shape);
-    printf("Shape: (%ld", PyLong_AsLong(PyTuple_GetItem(shape, 0)));
-    for (int i = 1; i < len; i++) {
-        printf(", %ld", PyLong_AsLong(PyTuple_GetItem(shape, i)));
-    }
-    printf(")\n");
-
-    // Access the elements of the array
-    // for (int i = 0; i < PyArray_SIZE(array); i++) {
-    //    printf("%ld ", PyLong_AsLong(PyArray_GetItem(array, i)));
-    // }
-    // printf("\n");
-
-    // Clean up
-    Py_DECREF(array);
-    Py_DECREF(numpy);
-    Py_Finalize();
-
-    return EXIT_SUCCESS;
+  // Initialize the Python interpreter
+  Py_Initialize();
+
+  // Import the NumPy module
+  PyObject* numpy = PyImport_ImportModule("numpy");
+
+  // Convert a Python list to a NumPy array
+  PyObject* list = PyList_New(3);
+  PyList_SetItem(list, 0, PyLong_FromLong(1));
+  PyList_SetItem(list, 1, PyLong_FromLong(2));
+  PyList_SetItem(list, 2, PyLong_FromLong(3));
+  PyObject* array = PyObject_CallMethod(numpy, "array", "O", list);
+
+  // Get the data type of the array
+  PyObject*   dtype = PyObject_GetAttrString(array, "dtype");
+  const char* str   = PyUnicode_AsUTF8(dtype);
+  printf("Data type: %s\n", str);
+
+  // Get the shape of the array
+  PyObject*  shape = PyObject_GetAttrString(array, "shape");
+  Py_ssize_t len   = PyTuple_Size(shape);
+  printf("Shape: (%ld", PyLong_AsLong(PyTuple_GetItem(shape, 0)));
+  for (int i = 1; i < len; i++) {
+    printf(", %ld", PyLong_AsLong(PyTuple_GetItem(shape, i)));
+  }
+  printf(")\n");
+
+  // Access the elements of the array
+  // for (int i = 0; i < PyArray_SIZE(array); i++) {
+  //    printf("%ld ", PyLong_AsLong(PyArray_GetItem(array, i)));
+  // }
+  // printf("\n");
+
+  // Clean up
+  Py_DECREF(array);
+  Py_DECREF(numpy);
+  Py_Finalize();
+
+  return EXIT_SUCCESS;
 }

PyBind11/CMakeLists.txt

@@ -0,0 +1,10 @@
+cmake_minimum_required(VERSION 3.20)
+project(linear LANGUAGES CXX)
+
+set(CMAKE_CXX_STANDARD 17)
+set(CMAKE_CXX_STANDARD_REQUIRED ON)
+
+find_package(Python COMPONENTS Interpreter Development.Module REQUIRED)
+find_package(pybind11 CONFIG REQUIRED)
+
+pybind11_add_module(linear "linear.cpp")

PyBind11/linear.cpp

@@ -0,0 +1,31 @@
+/**
+ * @file main.cpp
+ * @author Xuhua Huang
+ * @brief
+ * @version 0.1
+ * @date 2026-01-16
+ *
+ * @copyright Copyright (c) 2026
+ *
+ */
+
+#include <pybind11/numpy.h>
+#include <pybind11/pybind11.h>
+
+namespace py = pybind11;
+
+// y = a*x + b for a 1D array
+py::array_t<double> axpb(py::array_t<double, py::array::c_style | py::array::forcecast> x, double a, double b) {
+  auto                xin = x.unchecked<1>();
+  py::array_t<double> y(xin.shape(0));
+  auto                yout = y.mutable_unchecked<1>();
+
+  for (py::ssize_t i = 0; i < xin.shape(0); ++i) {
+    yout(i) = a * xin(i) + b;
+  }
+  return y;
+}
+
+PYBIND11_MODULE(linear, m) {
+  m.def("axpb", &axpb, "Compute y = a*x + b for a 1D NumPy array");
+}