def _update_epoch_data(params):
    """Prepare the data on horizontal shift."""
    start = params['t_start']
    n_epochs = params['n_epochs']
    end = start + n_epochs * len(params['epochs'].times)
    data = params['orig_data'][:, start:end]
    types = params['types']
    for pick, ind in enumerate(params['inds']):
        params['data'][pick] = data[ind] / params['scalings'][types[pick]]
    params['plot_fun']()
