def pad(args):
    """
    %prog pad blastfile cdtfile --qbed q.pad.bed --sbed s.pad.bed

    Test and reconstruct candidate PADs.
    """
    from jcvi.formats.cdt import CDT

    p = OptionParser(pad.__doc__)
    p.set_beds()
    p.add_option("--cutoff", default=.3, type="float",
                 help="The clustering cutoff to call similar [default: %default]")

    opts, args = p.parse_args(args)

    if len(args) != 2:
        sys.exit(not p.print_help())

    cutoff = opts.cutoff
    blastfile, cdtfile = args
    qbed, sbed, qorder, sorder, is_self = check_beds(blastfile, p, opts)

    cdt = CDT(cdtfile)
    qparts = list(cdt.iter_partitions(cutoff=cutoff))
    sparts = list(cdt.iter_partitions(cutoff=cutoff, gtr=False))

    qid, sid = {}, {}
    for i, part in enumerate(qparts):
        qid.update(dict((x, i) for x in part))
    for i, part in enumerate(sparts):
        sid.update(dict((x, i) for x in part))

    # Without writing files, conversion from PAD to merged PAD is done in memory
    for q in qbed:
        q.seqid = qid[q.seqid]
    for s in sbed:
        s.seqid = sid[s.seqid]

    qnames = range(len(qparts))
    snames = range(len(sparts))

    logmp = make_arrays(blastfile, qbed, sbed, qnames, snames)
    m, n = logmp.shape
    pvalue_cutoff = 1e-30
    cutoff = - log(pvalue_cutoff)

    significant = []
    for i in xrange(m):
        for j in xrange(n):
            score = logmp[i, j]
            if score < cutoff:
                continue
            significant.append((qparts[i], sparts[j], score))

    for a, b, score in significant:
        print("|".join(a), "|".join(b), score)

    logging.debug("Collected {0} PAR comparisons significant at (P < {1}).".\
                    format(len(significant), pvalue_cutoff))

    return significant