Set label of Dataset.

        Parameters
        ----------
        label : list, numpy 1-D array, pandas Series / one-column DataFrame or None
            The label information to be set into Dataset.

        Returns
        -------
        self : Dataset
            Dataset with set label.

def set_label(self, label):
        """Set label of Dataset.

        Parameters
        ----------
        label : list, numpy 1-D array, pandas Series / one-column DataFrame or None
            The label information to be set into Dataset.

        Returns
        -------
        self : Dataset
            Dataset with set label.
        """
        self.label = label
        if self.handle is not None:
            label = list_to_1d_numpy(_label_from_pandas(label), name='label')
            self.set_field('label', label)
        return self