def filter_paired(list):
    """
	require that both pairs are mapped in the sam file in order to remove the reads
	"""
    pairs = {}
    filtered = []
    for id in list:
        read = id.rsplit('/')[0]
        if read not in pairs:
            pairs[read] = []
        pairs[read].append(id)
    for read in pairs:
        ids = pairs[read]
        if len(ids) == 2:
            filtered.extend(ids)
    return set(filtered)
