Python Embedding

[jibarra]

I don't know if this is the correct forum but,

I am doing some Python Embedding from:
https://docs.python.org/3.6/extending/em...-embedding

I cannot figure out how to pass the keyword rosen from the C/Python API in the nelderMead function argument correctly.

I have tried hard-coding PyUnicode_DecodeFSDefault but it outputs a string into the Python when rosen itself is a type class
from scipy.

from scipy.optimize import minimize, rosen, rosen_der

def nelderMead(func):
    x0 = [1.3, 0.7, 0.8, 1.9, 1.2]
    res = minimize(func, x0, method='Nelder-Mead', tol=1e-6)
    print(res.x)

please advise .

[Gribouillis]

I cannot figure out how to pass the keyword rosen from the C/Python API in the nelderMead function argument correctly.

I don't understand what you want to do. Do you want to call function nelderMead? with which argument? from C, from python? Why can't you do it? Can you post your code?

[jibarra]

I want to call the nelderMead Python function from C, and pass in the keyword rosen that I've imported from from scipy.optimize import minimize, rosen, rosen_der from C into the nelderMead function. The problem is whenever is pass in a string or PyObject, python reads it as a type string but rosen is a type class. So the rosen parameter does not get invoked as a class but as a string.

C Code below:
//https://docs.scipy.org/doc/scipy/reference/generated/scipy.optimize.minimize.html

#include</usr/include/python3.6m/Python.h>


int main(){

PyObject *pName,*pFunc, *pValue, *pModule, *pOpt;

Py_Initialize();

//Access file in local folder where C file is stored
PyRun_SimpleString("import sys");
PyRun_SimpleString("sys.path.append(\".\")");

//Convert String to PyObject
pName = PyUnicode_DecodeFSDefault("Rosenbrock_Function");
pModule = PyImport_Import(pName);

Py_DECREF(pName);

if(pModule){
pFunc = PyObject_GetAttrString(pModule,"nelderMead");
Py_DECREF(pModule);
}
pOpt = PyUnicode_DecodeFSDefault("rosen");

pValue = PyObject_CallFunctionObjArgs(pFunc,pOpt,NULL);

Py_FinalizeEx();
return 0;
}

[Gribouillis]

You need to retrieve the 'rosen' attribute from the module as well. Here is a code that works for me (in python 3.5)

#include</usr/include/python3.5m/Python.h>

int main(){
    PyObject *pFunc, *pValue, *pModule, *pOpt;

    Py_Initialize();
    PyRun_SimpleString("import sys");
    PyRun_SimpleString("sys.path.append(\".\")");

    if(pModule = PyImport_ImportModule("Rosenbrock_Function")){
        if(pFunc = PyObject_GetAttrString(pModule,"nelderMead")){
            if(pOpt = PyObject_GetAttrString(pModule, "rosen")){
                pValue = PyObject_CallFunctionObjArgs(pFunc,pOpt,NULL);
                Py_DECREF(pOpt);
                Py_XDECREF(pValue);
            }
            Py_DECREF(pFunc);
        }
        Py_DECREF(pModule);
    }
    Py_Finalize();
    return 0;
}

Don't use PyUnicode_DecodeFSDefault unless you're dealing with filesystem paths.

[jibarra]

Thank you so much!