def _similar_compound_to_str(sdict, compound_idx):
    """
    inputs:
        sdict: a dict returned from get_similar_compounds()
        compound_index: index of current compound being considered
    returns:
        string with only non-breaking spaces or '*' if dict represents current compound
    """
    if sdict['index'] == compound_idx:
        return '*'
    return f"{sdict['index']}, {sdict['label']} {{RT-{sdict['rt'].rt_peak:.2f}}}".replace(' ', '\xa0')