def partial_transform(self, traj):
        """Featurize an MD trajectory into a vector space derived from
        residue-residue distances

        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

        Warning
        -------
        Only works for chain 0 for now.
        """
        seq_id = [k for k, v in self.all_sequences.items()
                  if v == traj.top.to_fasta(chain=0)][0]
        return self.feat_dict[seq_id].partial_transform(traj)
Featurize an MD trajectory into a vector space derived from
        residue-residue distances

        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

        Warning
        -------
        Only works for chain 0 for now.