我正在尝试创建一些python对象并使用C ++中的NumPy。我修改了一些我发现的例子。下面的代码找到NumPy模块,函数numpy.array但是为pValue返回null。我使用过Python3.4。任何人都可以解释为什么函数总是返回NULL?
#include <stdlib.h>
#include <iostream>
#include <vector>
#include <Python.h>
int runPython(int argc, char * argv[]) {
std::cout << "Hello from runPython()" << std::endl;
PyObject *pFunc;
PyObject *pValue, *pYVec;
int i;
Py_Initialize();
std::cout << Py_GetVersion() << std::endl;
PyObject *sys = PyImport_ImportModule("sys");
PyObject *path = PyObject_GetAttrString(sys, "path");
std::cout << PyList_Size(path) << std::endl;
Py_DecRef(path);
Py_DecRef(sys);
PyObject* item = PyList_GetItem(path,1);
std::cout << PyString_Check(item) << std::endl;
Py_DecRef(item);
PyObject *numpy = PyImport_ImportModule("numpy");
if (numpy != NULL) {
pFunc = PyObject_GetAttrString(numpy, "array"); //Get the function by its name
if (pFunc && PyCallable_Check(pFunc)) {
static const double yarr[] = {0,0,1,1,0,0,2,2,0,0,1,1,0,0};
std::vector<double> yvec (yarr, yarr + sizeof(yarr) / sizeof(yarr[0]) );
//Transfer the other C++ vector to a python list
pYVec = PyList_New(yvec.size());
for (i = 0; i < yvec.size(); ++i) {
pValue = PyFloat_FromDouble(yvec[i]);
if (!pValue) {
fprintf(stderr, "Cannot convert array value\n");
return 1;
}
PyList_SetItem(pYVec, i, pValue); //
}
//Call the python function
pValue = PyObject_CallMethodObjArgs(pFunc, pYVec);
if (pValue != NULL) {
printf("Result of call: %ld\n", PyInt_AsLong(pValue));
}
//Some error catching
else {
Py_DecRef(pValue);
Py_DecRef(pYVec);
//Py_DecRef(pFunc);
Py_XDECREF(pFunc);
Py_DecRef(numpy);
fprintf(stderr,"Call failed\n");
PyErr_Print();
return 1;
}
}
else {
if (PyErr_Occurred())
PyErr_Print();
fprintf(stderr, "Cannot find function \"%s\"\n", argv[2]);
}
//Py_DECREF(pModule);
}
else {
PyErr_Print();
fprintf(stderr, "Failed to load \"%s\"\n", argv[1]);
return 1;
}
Py_Finalize();
return 0;
}
int main ( int argc, char *argv[] )
{
std::cout << "Hello from main" << std::endl;
runPython(argc, argv);
std::cout << "Program finished" << std::endl;
return EXIT_SUCCESS;
}
产生输出
Hello from main
Hello from runPython()
3.4.0 (default, Apr 11 2014, 13:08:40)
[GCC 4.8.2]
7
0
Call failed
Program finished
答案 0 :(得分:0)
您对PyObject_CallMethodObjArgs
的论据不正确。事实上,我认为你正在调用错误的功能。 PyObject_CallFunctionObjArgs
看起来更合适。而不是
pValue = PyObject_CallMethodObjArgs(pFunc, pYVec);
试
pValue = PyObject_CallFunctionObjArgs(pFunc, pYVec, NULL);