C++ python Tutorial

[TOC]

环境配置VS Studio

c_cpp_properties.json

{
    "configurations": [
        {
            "name": "windows-gcc-x64",
            "includePath": [
                "${workspaceFolder}/**",
                "C:/Users/Simon/.conda/envs/torch_gpu/include/",
                "C:/Users/Simon/.conda/envs/torch_gpu/Lib/site-packages/numpy/core/include"
            ],
            "compilerPath": "D:/Tools/Mingw/mingw64/bin/gcc.exe",
            "cStandard": "${default}",
            "cppStandard": "c++11",
            "intelliSenseMode": "windows-gcc-x64",
            "compilerArgs": []
        }
    ],
    "version": 4
}

tasks.json

{
  "version": "2.0.0",
  "tasks": [
    {
      "type": "shell",
      "label": "C/C++: g++编译前清理",
      "command": "rm",
      "args": [
        "${workspaceRoot}/*.exe"
      ]
    },
    {
      "label": "build c++Callpython",
      "type": "shell",
      "command": "g++",
      "args": [
        "-g", "c++_python.cpp",
        "-I", "C:/Users/Simon/.conda/envs/torch_gpu/include/",
        "-I", "C:/Users/Simon/.conda/envs/torch_gpu/Lib/site-packages/numpy/core/include",
        "-L", "C:/Users/Simon/.conda/envs/torch_gpu/libs/*",
        "-o", "c++_python.exe"
      ],
      "group": {
        "kind": "build",
        "isDefault": true
      },
      "problemMatcher": [],
      "dependsOn":[
        "C/C++: g++编译前清理",
      ]
    }
  ]
}

// g++ -g c++_python.cpp -L ./libs/* -o c++_python.exe
// -fdiagnostics-color=always

0. Test Run

#include <iostream>

#include "numpy/arrayobject.h"
#include "Python.h"

using namespace std;

// ref: https://wenku.baidu.com/view/01fab1346f175f0e7cd184254b35eefdc8d315cd.html

int demo0(){

    Py_SetPythonHome(L"C:/Users/Simon/.conda/envs/torch_gpu");
    Py_Initialize();
    PyRun_SimpleString("print('hello')");
    Py_Finalize();

}

1. C++传参

call python method, set parameter ,return value

常用的有两种方法：

使用 PyTuple_New 创建元组， PyTuple_SetItem 设置元组值

PyObject* args = PyTuple_New(3);
PyObject* arg1 = Py_BuildValue("i", 100); // 整数参数
PyObject* arg2 = Py_BuildValue("f", 3.14); // 浮点数参数
PyObject* arg3 = Py_BuildValue("s", "hello"); // 字符串参数
PyTuple_SetItem(args, 0, arg1);
PyTuple_SetItem(args, 1, arg2);
PyTuple_SetItem(args, 2, arg3);

# 直接使用Py_BuildValue构造元组

PyObject* args = Py_BuildValue("(ifs)", 100, 3.14, "hello");
PyObject* args = Py_BuildValue("()"); // 无参函数
原文链接：https://blog.csdn.net/tobacco5648/article/details/50890106

int demo1()
{
    Py_SetPythonHome(L"C:/Users/Simon/.conda/envs/torch_gpu");
    Py_Initialize();

    PyObject *module = NULL;
    PyObject *pFunc = NULL;
    PyObject *pArg = NULL;
    PyObject *value = NULL;
    // 导入文件
    module = PyImport_ImportModule("pthonnx_ru");

    pFunc = PyObject_GetAttrString(module, "demo1"); // 找到函数地址
    pArg = Py_BuildValue("(S)", "my is c++ test");
    value = PyEval_CallObject(pFunc, pArg); // 调用函数
    float val;
    PyArg_Parse(value, "f", &val);
    // PyArg_ParseTuple(value, "f", &val);
    cout << "--val1--" << val << endl;

    pFunc = PyObject_GetAttrString(module, "Add");
    pArg = Py_BuildValue("i, i)", 21, 23);
    value = PyEval_CallObject(pFunc, pArg);
    PyArg_Parse(value, "f", &val);
    cout << "--val2--" << val << endl;

    PyRun_SimpleString("print('hello')");
    Py_Finalize();

    return 0;
}

2.传递List参数

int demo2()
{

    cout << "Hello World" << endl;

    Py_SetPythonHome(L"C:/Users/Simon/.conda/envs/torch_gpu");
    Py_Initialize();

    PyObject *module = NULL;
    PyObject *pFunc = NULL;
    PyObject *pArg = NULL;
    // 导入文件
    module = PyImport_ImportModule("pthonnx_ru");
    // 找到函数地址
    pFunc = PyObject_GetAttrString(module, "demo2");
    // Set Parameter
    PyObject *pyParams = PyList_New(0);
    PyList_Append(pyParams, Py_BuildValue("i", 5)); // float
    PyList_Append(pyParams, Py_BuildValue("i", 3));
    PyObject *args = PyTuple_New(1);
    PyTuple_SetItem(args, 0, pyParams);

    // 调用函数
    float val;
    PyObject *value = PyEval_CallObject(pFunc, args);
    PyArg_Parse(value, "f", &val);
    // PyArg_ParseTuple(value, "f", &val);
    cout << "--val--" << val << endl;

    PyRun_SimpleString("print('hello')");
    Py_Finalize();

    return 0;
}

3 python类操作，类属性，类成员函数 Todo

int demo3()
{
    cout << "Hello World" << endl;

    Py_SetPythonHome(L"C:/Users/Simon/.conda/envs/torch_gpu");
    Py_Initialize();

    PyObject *module = NULL;
    PyObject *pFunc = NULL;

    module = PyImport_ImportModule("pthonnx_ru"); // 导入文件
    pFunc = PyObject_GetAttrString(module, "demo2"); // 找到函数地址

    // 创建参数
    PyObject *pArgs = PyTuple_New(1);
    // 设置函数参数的值
    int InParm = 1;
    PyTuple_SetItem(pArgs, 0, PyLong_FromLong(InParm));

    // 调用函数
    float val;
    PyObject *value = PyEval_CallObject(pFunc, pArgs);
    PyArg_Parse(value, "f", &val);
    // PyArg_ParseTuple(value, "f", &val);
    cout << "--val--" << val << endl;

    Py_Finalize();
    return 0;
}

4 传递c++数组转python的list

int demo4(){
    Py_SetPythonHome(L"C:/Users/Simon/.conda/envs/torch_gpu");
    Py_Initialize();
    // #include "numpy/arrayobject.h"
    // api doc : https://numpy.org/doc/1.17/reference/c-api.array.html#importing-the-api
    import_array();

    PyObject *module = NULL;
    PyObject *pFunc = NULL;
    PyObject *pArgs = NULL;

    module = PyImport_ImportModule("pthonnx_ru");
    pFunc = PyObject_GetAttrString(module, "demo4");

    float buf[2][3];
    buf[0][0] = 0;
    buf[0][1] = 1.1230;
    buf[0][2] = 2.340;
    buf[1][0] = 4.540;
    buf[1][1] = 6.900;
    buf[1][2] = 8.090;

    pArgs = PyTuple_New(1);
    npy_intp dims[2] = {2, 3}; // 定义list的shape
    int ND = 2; // list 维度
    PyObject * pPyArray = PyArray_SimpleNewFromData(ND, dims, NPY_FLOAT, buf); // list dim,shape, type, buffer
    PyTuple_SetItem(pArgs, 0, pPyArray); // 变量转换
    PyEval_CallObject(pFunc, pArgs);

    Py_Finalize();
    return 0;
}

参考：

https://docs.python.org/2/extending/embedding.html

https://wenku.baidu.com/view/01fab1346f175f0e7cd184254b35eefdc8d315cd.html

https://numpy.org/doc/1.17/reference/c-api.array.html

https://numpy.org/doc/1.17/reference/c-api.array.html#importing-the-api