Function Math_fit_least_squares

Code/Source/PythonAPI/Math_PyModule.cxx:486–549

");

static PyObject *
Math_fit_least_squares(PyObject *self, PyObject *args)
{
  auto api = PyUtilApiFunction("OOii", PyRunTimeErr, __func__);
  int xOrder = 0;
  int yOrder = 0;

  PyObject *xtermsArg;
  PyObject *ytermsArg;

  if (!PyArg_ParseTuple(args, api.format,  &xtermsArg, &ytermsArg, &xOrder,&yOrder)) {
      return api.argsError();
  }

  int numberOfSamples = PyList_Size(xtermsArg);
  int numberOfSamplesY = PyList_Size(ytermsArg);
  if (numberOfSamples!= numberOfSamplesY) {
      api.error("The number of x terms ("+std::to_string(numberOfSamples)+") != the number of y terms ("+std::to_string(numberOfSamplesY)+".");
      return nullptr;
  }

  // Get an array of points from the xtermsArg list.
  int dim = 3;
  auto xt = GetPointsFromList(api, xtermsArg, dim, "x terms");
  if (xt == nullptr) {
      return nullptr;
  }

  // Get an array of points from the xtermsArg list.
  auto yt = GetPointsFromList(api, ytermsArg, dim, "y terms");
  if (yt == nullptr) {
      return nullptr;
  }

  // Perform the least squares fit.
  //
  auto mathObj = cvMath();
  double **mt = mathObj.createArray(xOrder,yOrder);
  if (mathObj.fitLeastSquares(numberOfSamples,xt,xOrder,yt,yOrder,mt) == SV_ERROR) {
     PyErr_SetString( PyRunTimeErr, "error in least squares fit" );
      mathObj.deleteArray(xt,numberOfSamples,xOrder);
      mathObj.deleteArray(yt,numberOfSamples,yOrder);
      api.error("Error performing the least squares fit.");
      return nullptr;
  }

  // create result string
  char r[2048];
  PyObject *pylist=PyList_New(xOrder);
  for (int i = 0; i < xOrder; i++) {
      r[0] = '\0';
      for (int j = 0; j < yOrder; j++) {
          sprintf(r,"%.6le ",mt[i][j]);
          PyObject *rr=PyBytes_FromString(r);
          PyList_SET_ITEM(pylist, i, rr);
     }
  }