def coerce(cls, string):
        """Create a :class:`Requirement` object from a given package spec."""
        match = re.match(cls.spec_regex, string)
        if not match:
            raise InvalidRequirementSpecError("could not parse requirement")
        package = match.group(1)
        if all(match.group(2, 3)):
            version = "".join(match.group(2, 3))
        else:
            version = None
        return cls(package, version)
def permutation_subjects_ktst(y):
    """Permute class labels of Contextual Disorder dataset for KTST.
    """
    yp = np.random.randint(0, 2, len(y)/2)
    yp = np.concatenate((yp, np.logical_not(yp).astype(int)))
    y_perm = np.arange(len(y))
    for i in range(len(y)/2):
        if yp[i] == 1:
            y_perm[i] = len(y)/2+i
            y_perm[len(y)/2+i] = i
    return y_perm