private method to synchronize the control section counters with the
        various parts of the control file.  This is usually called during the
        Pst.write() method.

def _update_control_section(self):
        """ private method to synchronize the control section counters with the
        various parts of the control file.  This is usually called during the
        Pst.write() method.

        """
        self.control_data.npar = self.npar
        self.control_data.nobs = self.nobs
        self.control_data.npargp = self.parameter_groups.shape[0]
        self.control_data.nobsgp = self.observation_data.obgnme.\
            value_counts().shape[0] + self.prior_information.obgnme.\
            value_counts().shape[0]

        self.control_data.nprior = self.prior_information.shape[0]
        self.control_data.ntplfle = len(self.template_files)
        self.control_data.ninsfle = len(self.instruction_files)
        self.control_data.numcom = len(self.model_command)