def remove(self, elem):
        """Remove a requirement.

        :param elem: a string or :class:`Requirement` instance.
        """
        if isinstance(elem, text_type):
            for requirement in self:
                if requirement.package == elem:
                    return super(Requirements, self).remove(requirement)
        return super(Requirements, self).remove(elem)
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