def partial_transform(self, traj):
        """Featurize an MD trajectory into a vector space via calculation
        of soft-bins over dihdral angle space.

        Parameters
        ----------
        traj : mdtraj.Trajectory
            A molecular dynamics trajectory to featurize.

        Returns
        -------
        features : np.ndarray, dtype=float, shape=(n_samples, n_features)
            A featurized trajectory is a 2D array of shape
            `(length_of_trajectory x n_features)` where each `features[i]`
            vector is computed by applying the featurization function
            to the `i`th snapshot of the input trajectory.

        See Also
        --------
        transform : simultaneously featurize a collection of MD trajectories
        """
        x = []
        for a in self.types:
            func = getattr(md, 'compute_%s' % a)
            _, y = func(traj)
            res = vm.pdf(y[..., np.newaxis],
                         loc=self.loc, kappa=self.kappa)
            #we reshape the results using a  Fortran-like index order,
            #so that it goes over the columns first. This should put the results
            #phi dihedrals(all bin0 then all bin1), psi dihedrals(all_bin1)
            x.extend(np.reshape(res, (1, -1, self.n_bins*y.shape[1]), order='F'))
        return np.hstack(x)
Featurize an MD trajectory into a vector space via calculation
        of soft-bins over dihdral angle space.

        Parameters
        ----------
        traj : mdtraj.Trajectory
            A molecular dynamics trajectory to featurize.

        Returns
        -------
        features : np.ndarray, dtype=float, shape=(n_samples, n_features)
            A featurized trajectory is a 2D array of shape
            `(length_of_trajectory x n_features)` where each `features[i]`
            vector is computed by applying the featurization function
            to the `i`th snapshot of the input trajectory.

        See Also
        --------
        transform : simultaneously featurize a collection of MD trajectories