发送C ++数组Python和背面（扩展C ++与numpy的） [英] Sending a C++ array to Python and back (Extending C++ with Numpy)
问题描述
我要发送一个 C ++ 数组一个python函数 numpy的阵列，并取回另一 numpy的阵列。与 numpy的文档和一些其他线程咨询和扭捏code后，终于在code是工作，但我想知道，如果这code写最佳考虑：
I am going to send a c++ array to a python function as numpy array and get back another numpy array. After consulting with numpy documentation and some other threads and tweaking the code, finally the code is working but I would like to know if this code is written optimally considering the:
- 的数组不必要的复制
C ++和numpy的（蟒蛇）。 - 的变量解引用正确
- 易于直接的方法。
C ++ code：
C++ code:
// python_embed.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#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;
}
在codeReview，有一个梦幻般的回答：<一href=\"http://$c$creview.stackexchange.com/questions/92266/sending-a-c-array-to-python-numpy-and-back/92353#92353\">Link...
In CodeReview, there is a fantastic answer: Link...
推荐答案
从我的经验，这似乎是pretty效率。
为了获得更高的效率了它试试这个：
http://ubuntuforums.org/showthread.php?t=1266059
From my experience that seems to be pretty efficient. To get even more efficiency out of it try this : http://ubuntuforums.org/showthread.php?t=1266059
使用编织你可以内联C / C ++ code在Python，这样可能是有用的。
Using weave you can inline C/C++ code in Python so that could be useful.
的http://docs.scipy.org/doc/scipy-0.15.1/reference/generated/scipy.weave.inline.html
下面是关于Python如何被使用，举例许多不同的语言之间的接口的连接。
Here's a link on how Python can be used to interface between many different languages along with examples.
HTTP：//docs.scipy。组织/ DOC / numpy的/用户/ C-info.python-AS-glue.html
这是如何numpy的数组传递给C ++使用用Cython一个快速和简单的例子：
This is a quick and easy example of how to pass numpy arrays to c++ using Cython:
HTTP：//blog.birving。 COM / 2014/05 /结业numpy的阵列之间 - 的python-and.html
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