def METHOD_NAME(self, filename):
    h5 = h5py.File(filename, "r")
    impulse_coords = h5['geometry/vertices'][:]
    impulse_slip = h5['vertex_fields/slip'][:,:,:].squeeze()
    h5.close()
    # Sort by y-coordinate.
    reorder = numpy.argsort(impulse_coords[:,1])
    self.impulse_coords = impulse_coords[reorder,:]
    self.impulse_slip = impulse_slip[:,reorder,:]