@classmethod
def export_to_hdf5(cls, h5_file, model, eids):
    """exports the elements in a vectorized way"""
    unused_comments = []
    nid = []
    cid = []
    mass = []
    X = []
    I = []
    for eid in eids:
        element = model.masses[eid]
        nid.append(element.nid)
        cid.append(element.cid)
        mass.append(element.mass)
        X.append(element.X)
        I.append(element.I)
    h5_file.create_dataset('eid', data=eids)
    h5_file.create_dataset('nid', data=nid)
    h5_file.create_dataset('cid', data=cid)
    h5_file.create_dataset('X', data=X)
    h5_file.create_dataset('I', data=I)
    h5_file.create_dataset('mass', data=mass)
