seq.py 文件源码

def base_complement(k):
    """ Return complement of base.

    Performs the subsitutions: A<=>T, C<=>G, X=>X for both upper and lower
    case. The return value is identical to the argument for all other values.

    :param k: A base.
    :returns: Complement of base.
    :rtype: str

    """
    try:
        return comp[k]
    except KeyError:
        sys.stderr.write(
            "WARNING: No reverse complement for {} found, returning argument.".format(k))
        return k