def test_Matrix_build_row_struct_index():
val_mat1_text = list(tools.ngram(test_text_df["text"].values[0], [1]))
val_mat2_text = list(tools.ngram(test_text_df["text"].values[1], [1]))
val_mat1 = ValuesMatrix(val_mat1_text, force2d="as_col")
val_mat2 = ValuesMatrix(val_mat2_text, force2d="as_col")
val_mat = ValuesMatrix(np.concatenate((val_mat1._1d_ngram(2),
val_mat2._1d_ngram(2)), axis=0))
states_matrix, idx_matrix = val_mat.build_row_struct_index()
assert np.array_equal(states_matrix._eval(idx_matrix), val_mat)
