Parameters
        ----------
        new_categories : array like
        String names of new categories. Length should be equal to number of documents

        Returns
        -------
        TermDocMatrix

def recategorize(self, new_categories):
        '''
        Parameters
        ----------
        new_categories : array like
        String names of new categories. Length should be equal to number of documents

        Returns
        -------
        TermDocMatrix
        '''
        assert len(new_categories) == self.get_num_docs()

        new_category_idx_store = IndexStoreFromList.build(set(new_categories))
        new_y = np.array(new_category_idx_store.getidxstrictbatch(new_categories))

        new_tdm = self._make_new_term_doc_matrix(self._X, self._mX, new_y, self._term_idx_store, new_category_idx_store,
                                                 self._metadata_idx_store, new_y == new_y)
        return new_tdm