def _update_dprx(self):
super(ExpCM_fitprefs, self)._update_dprx()<EOL>j = <NUM_LIT:0><EOL>if '<STR_LIT>' in self.freeparams:<EOL><INDENT>self.dprx['<STR_LIT>'].fill(<NUM_LIT:0>)<EOL>for r in range(self.nsites):<EOL><INDENT>for i in range(N_AA - <NUM_LIT:1>):<EOL><INDENT>zetari = self.zeta[j]<EOL>self.dprx['<STR_LIT>'][j][r] = (self.prx[r] / zetari) * (<EOL>(CODON_TO_AA == i).astype('<STR_LIT:float>') -<EOL>((CODON_TO_AA == i).astype('<STR_LIT:float>') * self.prx[r]).sum())<EOL>j += <NUM_LIT:1><EOL><DEDENT><DEDENT><DEDENT>
Update `dprx`.