How to pass an array from C++ to an embedded python

细节问题可以查看： 

ubuntu下C++如何调用python程序，gdb调试C++代码

下面是C++调用Python二维数组传递的问题：

#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION#include "Python.h"#include "numpy/arrayobject.h"#include<iostream>using namespace std;int _tmain(int argc, _TCHAR* argv[]){    Py_SetProgramName(argv[0]);    Py_Initialize();    import_array()    // Build the 2D array    PyObject *pArgs, *pReturn, *pModule, *pFunc;    PyArrayObject *np_ret, *np_arg;    const int SIZE{ 10 };    npy_intp dims[2]{SIZE, SIZE};    const int ND{ 2 };    long double(*c_arr)[SIZE]{ new long double[SIZE][SIZE] };    long double* c_out;    for (int i{}; i < SIZE; i++)        for (int j{}; j < SIZE; j++)            c_arr[i][j] = i * SIZE + j;    np_arg = reinterpret_cast<PyArrayObject*>(PyArray_SimpleNewFromData(ND, dims, NPY_LONGDOUBLE,         reinterpret_cast<void*>(c_arr)));    // Calling array_tutorial from mymodule    PyObject *pName = PyUnicode_FromString("mymodule");    pModule = PyImport_Import(pName);    Py_DECREF(pName);    if (!pModule){        cout << "mymodule can not be imported" << endl;        Py_DECREF(np_arg);        delete[] c_arr;        return 1;    }    pFunc = PyObject_GetAttrString(pModule, "array_tutorial");    if (!pFunc || !PyCallable_Check(pFunc)){        Py_DECREF(pModule);        Py_XDECREF(pFunc);        Py_DECREF(np_arg);        delete[] c_arr;        cout << "array_tutorial is null or not callable" << endl;        return 1;    }    pArgs = PyTuple_New(1);    PyTuple_SetItem(pArgs, 0, reinterpret_cast<PyObject*>(np_arg));    pReturn = PyObject_CallObject(pFunc, pArgs);    np_ret = reinterpret_cast<PyArrayObject*>(pReturn);    if (PyArray_NDIM(np_ret) != ND - 1){ // row[0] is returned        cout << "Function returned with wrong dimension" << endl;        Py_DECREF(pFunc);        Py_DECREF(pModule);        Py_DECREF(np_arg);        Py_DECREF(np_ret);        delete[] c_arr;        return 1;    }    int len{ PyArray_SHAPE(np_ret)[0] };    c_out = reinterpret_cast<long double*>(PyArray_DATA(np_ret));    cout << "Printing output array" << endl;    for (int i{}; i < len; i++)        cout << c_out[i] << ' ';    cout << endl;    // Finalizing    Py_DECREF(pFunc);    Py_DECREF(pModule);    Py_DECREF(np_arg);    Py_DECREF(np_ret);    delete[] c_arr;    Py_Finalize();    return 0;}

如果Python返回是一个list对象，则：

 // some code omitted... cout<<"Integer List Show:"<<endl; PyObject *pFuncTwo     = PyDict_GetItemString(pDict, "IntegerListReturn"); PyObject *FuncTwoBack  = PyObject_CallObject (pFuncTwo, nullptr);//返回List对象 if(PyList_Check(FuncTwoBack)){ //检查是否为List对象     int SizeOfList = PyList_Size(FuncTwoBack);//List对象的大小，这里SizeOfList = 3     for(Index_i = 0; Index_i < SizeOfList; Index_i++){         PyObject *ListItem = PyList_GetItem(FuncTwoBack, Index_i);//获取List对象中的每一个元素         int NumOfItems = PyList_Size(ListItem);//List对象子元素的大小，这里NumOfItems = 3         for(Index_k = 0; Index_k < NumOfItems; Index_k++){             PyObject *Item = PyList_GetItem(ListItem, Index_k);//遍历List对象中子元素中的每个元素             cout << PyInt_AsLong(Item) <<" "; //输出元素             Py_DECREF(Item); //释放空间         }         Py_DECREF(ListItem); //释放空间     }     cout<<endl; }else{     cout<<"Not a List"<<endl; }

如果是一个二维的list，则：

/*Return the List which contains Numpy Array*/PyObject *pFuncOne    = PyDict_GetItemString(pDict, "ArrayListReturn");PyObject *FuncOneBack = PyObject_CallObject(pFuncOne, nullptr);int Index_i = 0, Index_k = 0, Index_m = 0, Index_n = 0;if(PyList_Check(FuncOneBack)){    int SizeOfList = PyList_Size(FuncOneBack);    for(Index_i = 0; Index_i < SizeOfList; Index_i++){        PyArrayObject *ListItem = (PyArrayObject *)PyList_GetItem(FuncOneBack, Index_i);//读取List中的PyArrayObject对象，这里需要进行强制转换。        int Rows = ListItem->dimensions[0], columns = ListItem->dimensions[1];        cout<<"The "<<Index_i<<"th Array is:"<<endl;        for(Index_m = 0; Index_m < Rows; Index_m++){            for(Index_n = 0; Index_n < columns; Index_n++){                cout<<*(double *)(ListItem->data + Index_m * ListItem->strides[0] + Index_n * ListItem->strides[1])<<" ";//访问数据，Index_m 和 Index_n 分别是数组元素的坐标，乘上相应维度的步长，即可以访问数组元素            }            cout<<endl;        }        Py_DECREF(ListItem);    }}else{    cout<<"Not a List"<<endl;}

c++传给Python一个数组：（第一个程序有点复杂）

    double CArrays[3][3] = {{1.3, 2.4, 5.6}, {4.5, 7.8, 8.9}, {1.7, 0.4, 0.8}}; //定义一个3 X 3的数组    npy_intp Dims[2] = {3, 3}; //给定维度信息    PyObject *PyArray  = PyArray_SimpleNewFromData(2, Dims, NPY_DOUBLE, CArrays); //生成包含这个多维数组的PyObject对象，使用PyArray_SimpleNewFromData函数，第一个参数2表示维度，第二个为维度数组Dims,第三个参数指出数组的类型，第四个参数为数组    PyObject *ArgArray = PyTuple_New(1);    PyTuple_SetItem(ArgArray, 0, PyArray); //同样定义大小与Python函数参数个数一致的PyTuple对象    PyObject *pFuncFive = PyDict_GetItemString(pDict, "PassArrayFromCToPython");    PyObject_CallObject(pFuncFive, ArgArray);//调用函数，传入Numpy Array 对象。