self.index_to_drop , _ = zip(*sorted(zip(range(X.shape[0]), X.sum(axis=0).getA1()),
                                key=lambda x: x[1], reverse=True)[:self.params['n']])
all_cols = np.arange(X.shape[1])
cols_to_keep = np.where(np.logical_not(np.in1d(all_cols, self.index_to_drop)))[0]
return X[:, cols_to_keep]