Returns the :attr:`InferenceResult.solutions` as a plottable 2d trajectory.

        :param x_axis: the variable to be on the x axis of projection
        :param y_axis: the variable to be on the y axis of preojection
        :return: a tuple x, y specifying lists of x and y coordinates of projection

def solutions_as_2d_trajectories(self, x_axis, y_axis):
        """
        Returns the :attr:`InferenceResult.solutions` as a plottable 2d trajectory.

        :param x_axis: the variable to be on the x axis of projection
        :param y_axis: the variable to be on the y axis of preojection
        :return: a tuple x, y specifying lists of x and y coordinates of projection
        """
        if not self.solutions:
            raise Exception('No intermediate solutions returned. '
                            'Re-run inference with return_intermediate_solutions=True')

        index_x = self.parameter_index(x_axis)
        index_y = self.parameter_index(y_axis)

        x, y = [], []
        for parameters, initial_conditions in self.solutions:
            all_values = parameters + initial_conditions
            x.append(all_values[index_x])
            y.append(all_values[index_y])

        return x, y