Call sourmash ani in C++

sourmash_ani.cpp

#include <Python.h>
#include <iostream>

using namespace std;

class toANI {
public:
    PyObject* moduleMainString, * moduleMain, * func;

    toANI() {
        Py_Initialize();
        PyRun_SimpleString("from sourmash.distance_utils import containment_to_distance\n");
        moduleMainString = PyUnicode_FromString("__main__");
        moduleMain = PyImport_Import(moduleMainString);
        PyRun_SimpleString("def to_ani(a,b,c,d): return containment_to_distance(a, b, c, n_unique_kmers=d).ani");
        func = PyObject_GetAttrString(moduleMain, "to_ani");
    }

    float calculate(float containment, long kSize, long scale, long n_unique_kmers) {
        PyObject* args = PyTuple_Pack(4,
            PyFloat_FromDouble(containment),
            PyLong_FromLong(kSize),
            PyLong_FromLong(scale),
            PyLong_FromLong(n_unique_kmers)
        );
        PyObject* result = PyObject_CallObject(func, args);
        return PyFloat_AsDouble(result);
    }
};

int main() {
    toANI ANI;
    int kSize = 31;
    float containment = 0.0174494;
    int scale = 1000;
    int n_unique_kmers = 4996000;
    float ani = ANI.calculate(containment, kSize, scale, n_unique_kmers);

    cout << "ani= " << ani << endl;
}