I am trying to pass a 2D array from C++ to Python function but the PyObject_CallObject
function is returning NULL
.This happens in case of 1D array as well. It works fine when I do not pass any argument or in case the argument is just single variable and not an array. My code is as follows:
#include <stdio.h>
#include <Python.h>
#include <pyhelper.hpp>
#include <string>
#define NPY_NO_DEPRECATED_API NPY_1_7_API_VERSION
#include <numpy/arrayobject.h> // For capturing the output values given by detector Python inference code
using namespace std;
PyObject *PythonInitialize(string script_name, string function_name);
int main(int argc, char *argv[])
{
if (!Py_IsInitialized())
{
Py_InitializeEx(0); // Initialize the Python interpreter
}
PyObject *PythonDetectorFunction, *PythonDetectorFunctionArguments;
PythonDetectorFunction = PythonInitialize("test", "getsum"); //getint, getsum
PythonDetectorFunctionArguments = PyTuple_New(1); // Reference count incremented. Need to handle the reference counting
if (PythonDetectorFunctionArguments == NULL)
PyErr_Print();
if (PyArray_API == NULL)
{
import_array();
}
float data[2][4] = {{1.2, 3.4, 5.6, 7.8}, {1.2, 3.4, 5.6, 7.8}};
npy_intp dims[2] = {2, 4};
PythonDetectorFunctionArguments = PyArray_SimpleNewFromData(1, dims, NPY_FLOAT, data);
PyObject *PythonDetectorFeatureMaps = PyObject_CallObject(PythonDetectorFunction, PythonDetectorFunctionArguments); // Will contain the output given by Python code
if (PythonDetectorFeatureMaps != NULL)
printf("PythonDetectorFeatureMaps: %p\n", PythonDetectorFeatureMaps);
else
printf("PythonDetectorFeatureMaps is NULL.\n");
Py_DECREF(PythonDetectorFunction);
Py_DECREF(PythonDetectorFunctionArguments);
//Py_DECREF(PythonDetectorFeatureMaps);
}
PyObject *PythonInitialize(string script_name, string function_name)
{
PyObject *pName, *pModule, *pFunc;
string PythonCodeImportStatement = "sys.path.append(os.getcwd())";
PyRun_SimpleString("import sys, os");
PyRun_SimpleString(PythonCodeImportStatement.c_str()); // Relative path for the python code
// pNmae is the name of the python script/module to be called
pName = PyUnicode_FromString(script_name.c_str()); // Reference count incremented. Need to handle the reference counting
if (pName == NULL)
PyErr_Print();
// Getting the Python module reference inside of the C code
pModule = PyImport_Import(pName);
if (pModule == NULL)
PyErr_Print();
// Python function reference
pFunc = PyObject_GetAttrString(pModule, function_name.c_str()); // Reference count incremented. Need to handle the reference counting
if (pFunc == NULL)
PyErr_Print();
// Refrence count clean-up
Py_XDECREF(pName);
Py_XDECREF(pModule);
//Py_XDECREF(pFunc);
return pFunc;
}
Python function in test.py:
def getsum(tuple1):
print('Python function getsum() called')
return None
Can someone point out the mistake?
PyObject_CallObject
takes a callable and a tuple of arguments for the callable, or NULL for no arguments. You're trying to pass it a NumPy array instead of an argument tuple.