Originally posted by **ghost** February 13, 2023
Hello,
First of all, thanks for the creation of this project, tools for working with NARMAX are not easily available. I am currently evaluating SysIdentPy to be used at work and I am going through some examples and found this example throughs up the following error:
```
ValueError Traceback (most recent call last)
Input In [8], in ()
----> 1 model.fit(X=x_train, y=y_train)
2 yhat = model.predict(X=x_valid, y=y_valid)
3 rrse = root_relative_squared_error(y_valid, yhat)
File ~/sysidentpy/sysidentpy/model_structure_selection/forward_regression_orthogonal_least_squares.py:476, in FROLS.fit(self, X, y)
471 self.regressor_code = self.regressor_space(
472 self.non_degree, self.xlag, self.ylag, self._n_inputs, self.model_type
473 )
475 if self._order_selection is True:
--> 476 self.info_values = self.information_criterion(reg_matrix, y)
478 if self.n_terms is None and self._order_selection is True:
479 model_length = np.where(self.info_values == np.amin(self.info_values))
File ~/sysidentpy/sysidentpy/model_structure_selection/forward_regression_orthogonal_least_squares.py:359, in FROLS.information_criterion(self, X_base, y)
356 n_theta = i + 1
357 regressor_matrix = self.error_reduction_ratio(X_base, y, n_theta)[2]
--> 359 tmp_theta = getattr(self, self.estimator)(regressor_matrix, y)
361 tmp_yhat = np.dot(regressor_matrix, tmp_theta)
362 tmp_residual = y[self.max_lag :] - tmp_yhat
File ~/sysidentpy/sysidentpy/parameter_estimation/estimators.py:255, in Estimators.recursive_least_squares(self, psi, y)
253 k = np.divide(k_numerator, k_denominator)
254 self.xi[i, 0] = y[i, 0] - np.dot(psi_tmp.T, theta[:, i - 1])
--> 255 theta[:, i] = list(theta[:, i - 1].reshape(-1, 1) + k.dot(self.xi[i, 0]))
257 p1 = p.dot(psi[i, :].reshape(-1, 1)).dot(psi[i, :].reshape(-1, 1).T).dot(p)
258 p2 = (
259 psi[i, :].reshape(-1, 1).T.dot(p).dot(psi[i, :].reshape(-1, 1))
260 + self._lam
261 )
ValueError: setting an array element with a sequence. The requested array would exceed the maximum number of dimension of 1.
```
Could you please give me a clue of how to make it work?
Have python 3.9, SysIdentPy 0.2.0 running on Mac Monterrey
Thanks in advance
Discussed in https://github.com/wilsonrljr/sysidentpy/discussions/92