def _update_Pxy(self):
scipy.copyto(self.Pxy_no_omega, self.Phi_x.transpose(),<EOL>where=CODON_SINGLEMUT)<EOL>self.Pxy_no_omega[<NUM_LIT:0>][CODON_TRANSITION] *= self.kappa<EOL>self.Pxy = self.Pxy_no_omega.copy()<EOL>self.Pxy[<NUM_LIT:0>][CODON_NONSYN] *= self.omega<EOL>_fill_diagonals(self.Pxy, self._diag_indices)<EOL>
Update `Pxy` using current `omega`, `kappa`, and `Phi_x`.