Private method to perform log10 transformation for ensemble

        Parameters
        ----------
        inplace: bool
            transform self in place

        Returns
        -------
        ParameterEnsemble : ParameterEnsemble
            if inplace is False

        Note
        ----
        Don't call this method unless you know what you are doing

def _transform(self,inplace=True):
        """ Private method to perform log10 transformation for ensemble

        Parameters
        ----------
        inplace: bool
            transform self in place

        Returns
        -------
        ParameterEnsemble : ParameterEnsemble
            if inplace is False

        Note
        ----
        Don't call this method unless you know what you are doing

        """
        if self.istransformed:
            #raise Exception("ParameterEnsemble already transformed")
            return

        istransformed = self.pst.parameter_data.loc[:,"partrans"] == "log"
        if inplace:
            #self.loc[:,istransformed] = np.log10(self.loc[:,istransformed])
            self.loc[:,:] = (self.loc[:,:] * self.pst.parameter_data.scale) +\
                             self.pst.parameter_data.offset
            self.loc[:,istransformed] = self.loc[:,istransformed].applymap(lambda x: math.log10(x))

            self.__istransformed = True
        else:
            vals = self.pst.parameter_data.parval1.copy()
            new_en = ParameterEnsemble(pst=self.pst.get(),data=self.loc[:,:].copy(),
                              columns=self.columns,
                              mean_values=vals,istransformed=True)
            new_en.loc[:,:] = (new_en.loc[:,:] * self.pst.parameter_data.scale) +\
                             new_en.pst.parameter_data.offset
            new_en.loc[:,istransformed] = self.loc[:,istransformed].applymap(lambda x: math.log10(x))
            return new_en